Lesson plans for Physics Grade 9

Preface
The Government of Punjab has a strong desire to improve the quality of teaching and learning
in the classroom. Various initiatives have been undertaken for provision of quality education
to students in the Province. Provision of quality education at secondary level is an important
step towards building an education system meant to contribute meaningfully towards
development of our society. To achieve the desired goal, activity oriented training for
secondary school teachers based on modern teaching methodologies has been considered
imperative and crucial.
Directorate of Staff Development (DSD) has been training in-service and pre-service
public school teachers and developing educational material since its inception. Considering
the quality work produced over the years, the task of development of the Teachers' Guides for
secondary school teachers in the subjects of English, Physics, Chemistry, Biology and
Mathematics was assigned to the Directorate of Staff Development by the Provincial
Government.
DSD worked in collaboration with over three hundred professionals i.e. Teachers, Book
Writers and Teacher Trainers from both public and private educational institutions in the
subject of English, and Mathematics who worked in groups to Physics, Chemistry, Biology
develop these comprehensive Teachers' Guides. These Teachers' Guides with textbooks are
aimed to achieve Students' Learning Outcomes (SLOs) through the teaching materials and
methodologies which suit varying teaching and learning contexts of Punjab. These Teachers'
Guides will help secondary school teachers to deliver and further plan their content lessons,
seek basic information on given concepts and topics, and assess students' understanding of
the taught concepts.
The DSD team acknowledges the cooperation extended by various public & private,
national and international organizations in the preparation of Teachers' Guides. DSD
recognizes the contribution made by all developers and reviewers belonging to following
organizations including German International Cooperation Agency (GIZ), Institute of
Education and Research (IER) Punjab University, Government Science College, International
School of Choueifat, Crescent Model Higher Secondary School, Punjab Textbook Board,
Lahore Grammar School, Himayat-e-Islam Degree College, SAHE, PEAS, NEEC, HELP
Foundation, Ali lnstitute of Education, Beaconhouse School System, ALBBS, The Educators,
Divisional Public School, The City School, AFAQ, Portal, LACAS, Children's Library Complex
(CLC) and GICW Lahore, Govt. Higher Secondary Schools and Govt. Colleges for Elementary
Teachers in Punjab.
( Nadeem Irshad Kayani)
Programme Director
Directorate of Staff Development, Punjab
Teachers’ Guide Lesson Plans: Physics

The students will describe:
the crucial role of Physics in Science,
Technology and Society.
list with brief description the various
branches of physics
Students’ Learning Outcomes
1
Information for Teachers
Physics is a natural science which deals with the
study of properties of matter, energy and
Introduction to Physics111
UNIT
T O P I C
Physical Quantities and Measurement
Lesson Plan
1
Grade IX
their mutual relationship.
Physics tires to explain how things work or
why things happen.' The laws of physics can
describe how objects fall, how light travels,
how a rainbow is made, or how a telescope
works. Why does an apple fall? Why does light
travel in straight lines? Why do magnets
attract? Why does water boil? Practically
speaking, physics is a guide to action in the
complex world of natural phenomenon.
The various branches of physics include
mechanics, Thermal Physics, Optics, Waves
and oscillations, Sound, electromagnetism,
sublima
tion
deposition
condensa
tion
e
v
apor
a
tion
melting
solidificationsolid liquid
gas
Teachers’ Guide Lesson Plans: Physics

2
atomic and Molecular Physics, Nuclear
Physics, Plasma physics and solid state
physics.
There are some branches of physics under
which we study the combine concepts of
physics and other branches of science i.e.
astrophysics, geophysics and biophysics.
Discoveries in physics have led to the
inventions of thousands of machines that
affect our everyday life. Electricity, television,
transport, robots and electronics are few
examples. All product of modern technology
are applications of the principles of the
physics. It is vital that students understand
the interrelationship of science, technology
and society.
Duration/Number of Period
80 mins/2period
Material/Resources Required
Black board , Posters including various branches
of physics, Textbook of grade IX, beakers,
magnet, sprit lamp, prism etc.
Introduction
Activity
Ask the students, do they know that
what is happening around us? Can they
explain the phenomena like
o light travels in straight lines
o how sound is produced?
o things fall towards ground
o conversion of different states of
matters
o creation of rainbows and
o lightening etc.
Write students' responses on the
blackboard or chart paper and explain to them that physics is not a body of
facts, but rather a process of asking
questions, designing experiments and theories to answer those questions
which come in mind about the things
and happenings around us.
We can say that physics tries to explain
how things work or why things happen.
Development
Activity 1
Draw a concept map of physics and its
various branches on the blackboard.
Sample concept map is given on next
page.
To further strengthen the concepts of
students divide them in groups of 5
students and take them to the library to
explore the definition of physics and its
main branches as given in the concept
map.
Guide them where needed in
completing their tasks.
After the completion of the task, select
one representative from each group to
present their work.
Sum up the activity by sharing with
them that whole universe is constituted
of matter and energy, physics is that
branch of physical sciences which
explains the properties of matter and
energy and of their mutual relationship.
Teachers’ Guide Lesson Plans: Physics

3
PHYSICS
is the science that
deals with the
ideas of
can be studied in
terms of its
can be studied in
terms of its
properties
relationships
with energy
relationships
with matter
properties
in the fields of
Activity 2
Divide the class in different groups. Provides the pictures based on the various branches of
physics to the students and asks them to discuss it in groups . They can discuss the things with the
teacher if they find something difficult . The students are asked to make preparation for the
classroom quiz program on the Topic ”Branches of Physics”
Classroom Quiz Program sheet
Sr.

No

Area of study

Pictures

Branch of Physics
with relevant natural
phenomena
1. It is the study of
physics which deals
with the motion of
bodies.

-----------------------------
-----------------------------
-----------------------------
---------------------------
Matter Energy
Mechanics Thermal Physics Light, Waves and
Sound
Electricity and
Magnetism
Atomic and
nuclear physics
Teachers’ Guide Lesson Plans: Physics

4
2.It examines the
structure, properties,
and behavior of the
atom.

-----------------------------
-----------------------------
-----------------------------
---------------------------
3. It analyses the
relationship between
electrical and
magnetic forces.

-----------------------------
-----------------------------
-----------------------------
---------------------------
4. Branch of Physics
which Examines the
structure , properties
and behavior of
molecules.

-----------------------------
-----------------------------
-----------------------------
---------------------------
5. It is concerned
with the
structure and
properties of the
atomic nucleus and it
deals with nuclear
reactions and their
applications like
fission and fusion
reactions

-----------------------------
-----------------------------
-----------------------------
---------------------------
6. Optics is the study of
nature and behavior
of light

-----------------------------
-----------------------------
-----------------------------
---------------------------
Teachers’ Guide Lesson Plans: Physics

5
7.

Plasma physics is
concerned with the
study of highly
ionized gases -

-----------------------------
-----------------------------
-----------------------------
---------------------------

8.

The study of the
behavior of electric
charges and the fields
they create in their
surrounding space

-----------------------------
-----------------------------
-----------------------------
---------------------------
9. A branch of physics
concerned
with the study of the
physical and chemical
properties of material
objects and energy
sources situated
outside the
boundaries of the
earth's atmosphere

-----------------------------
-----------------------------
-----------------------------
---------------------------

10

This is the branch of
physics that studies
heat and its
relationship with
other forms

of energy.

-----------------------------
-----------------------------
-----------------------------
---------------------------

Activity 3
Ask the students to plan a demonstration in pairs showing simple principles of physics and
explain their applications in everyday life. Write the following topics on the board:
o Metal expand when heated.
o Movement of particles
o Light travels in straight lines.
o Energy cannot be created nor destroyed, thrhoug it can be changed from one form into
another.
o Lawsof reflection
o Magnetism
Teachers’ Guide Lesson Plans: Physics

6
Conclusion/Sum up
Conclude the lesson by recalling the:
o definition of physis that it is the branch of
science which deals with the study of
properties of matter and energy along
with their mutual interaction.
o various branches of physics.
o various aspects of nature that they not
only provide us physical comfort through
their new inventions and researches but
also provide the vital evidences required
to understand nature.
o Sduty of physics makes students
independent inquireres about the natural
world
Assessment
List any three phenomenon occurring around
us and explain their application in the society.
Make a list of things in your home that use
electricity from the mains and from electric
cells.
Describe application of principles of physics in
your daily life.
Follow-up
ask the students to prepare a list of some technology
based instruments that they commonly see when they
visit a school, a house and a factory etc.
Teachers’ Guide Lesson Plans: Physics
Questions for Students Hints for Teachers
Communication means
improved , Service delivery
enhanced , learning
opportunity increased , Less
reading materials required ,
Bridging with international
community of children access
to the knowledge world
Computers,
Overhead projectors,
printer,
telephone,
cell phone,
fan etc
When you enter the school,
what kind of devices do you
find over there that operate
using some kind of technology?
Communication means
improved , Comfortable level of
living improved , less time
required to complete house
hold duties , Bridging with the
people around the globe
Computers, television,
microwave oven, Fans,
Air conditioners, Refrigerator,
Iron, Thermometer
Telephones etc
When you enter in your house,
what kind of devices do you
find over there that operate
using some kind of technology?
More production with less
effort , quality of products
enhanced , work force well
managed , communication
means increased , bridging
with stake holders at the local ,
national and international level
lifts, electrical fuses ,
Cars, Computers,
elevators,
machinery
When you enter in some
factory what kind of devices
do you find over there that
operate using some
technology?
1.
2.
3.
Effect on the way of lifeTechnology based instrumentsQuestionsNo.

The students will be able to:
describe the need using significant figures
for the recording and stating results in the
laboratory.
Students’ Learning Outcomes
7
Information for Teachers
In any measurement, the accurately known
digits and the first doubtful digit are called
significant figures.
An introduction to
Significant Figures
111
UNIT
T O P I C
Physical Quantities and Measurement
Lesson Plan
2
Grade IX
The result of an experiment cannot contain
more number of significant figures than the minimum number of significant figures in any
of the observed quantities.
The number or numbers, other than the
power of 10, which are given in a
measurement, are called significant figures
they indicate the precision with which a
particular measurement has been made.
Determining the Number of Significant
Figures here are a few rules to help you
determine how many S.F. are in a given
5 6 7 8 9 10 11 12 13 14
object
Teachers’ Guide Lesson Plans: Physics

8
Sample
Number
# of
S.F.
Significant
Digit
Hints
123.654 6 4
all digits are
significant
123.000 6 0
trailing zeros
after decimal
are significant
0.000654 3 4
leading zeros
are only
placeholders,
hence not
significant
100.32 5 2
middle zeros
are always
significant
5400 ? ?
don't know-as
scale used is
not known
Significant Figures in Scientific Notation.
As mentioned above, we cannot always take a
number out of context and determine the
number of S.F. For this reason (and also because
scientists get tired of carrying around lots of
zeros!) scientists usually write numbers using
scientific notation. When we convert a number to
scientific notation, we get rid of any non-
significant zeros.
Significant figures originally come from
measurements. When measuring, you may
estimate one decimal place beyond what the
measuring device shows. When you do this,
then: All digits in your measurement are
significant except place-holder zeroes.
number, and which of the digits is the least
significant one:
1. Integers are exact and are considered to have
an infinite number of S.F.; i.e. 2 is understood
to be 2.0000000….
2. Numerical constants such as can have as
many S.F. as you need e.g. 3.14, 3.14159,
3.14159265….
3. If the number is neither an integer nor a
numerical constant, then the number of S.F. is
equal to the number of digits excluding
certain zeros that act only as "placeholders."
In a number with a decimal point, any leading
zeros are placeholders and are not significant,
but trailing zeros in this case are significant. In
a number without a decimal point, trailing
zeros might or might not be significant; you
can only tell from the context!
In any case, the least significant digit is then the
significant digit that is farthest to the right. For
our purposes, the accuracy of any quoted value
can be assumed to be ± 1 of the least significant
digit, unless stated otherwise.
Here are some examples to help you practice:
Duration/Number of Periods
80 mins/2 period
Material/Resources Required
Meter rod, pencil, pictures, Board, beaker, vernier
calliper, bean, jar and textbook IX.
Introduction
Activity 1
Ask students what they think. Is
measurement different from counting?
Write their responses on the board.
Ask students to count windows of their
classroom, note their responses on the
board. Do all students answer exactly
the same?
Activity 2
Invite 3-4 students, provide them a
metal strip and a ruler and ask them
how long the metal strip is?
Teachers’ Guide Lesson Plans: Physics

9
How large this uncertainty is depends to
a high degree on the type of measuring
device used as well as how it is used.
For example, suppose that three
students were told to determine the
length of a piece of metal and were
given a tape measure whose smallest
markings were at 0.1 centimeter
intervals.
Record their reading on the board. Are
the answers of all students exactly the
same? (yes)
Explain to students that a measurement
is very different from counting, even
though both associate numbers with
notions.
Demonstrate the difference between
counting and measuring. Explain it
telling the students that we can count
the number of beans in a jar, and know it
exactly but we cannot measure the
height of the jar exactly. There is no such
thing as a exact measurement. All
measurements include uncertainties. In
scientific research most accurate
measurement are required. To record
the most correct measurement, a
scientist always keeps in view the
uncertainties in the measurement. Help
the students to realize that we often use
approximations while discussing
measurements. Every measurement,
whether it is made by students or a
professional scientist, is subject to
uncertainty. A digit in a number is said to
be a significant figure when it is known
with some reliability.
If you take your calculator and multiply
1.378 times 2.3 you will get 3.1694 as a
result. If you divide 3.7 by 1.336 you will
get 2.769461078. These results are
"correct" in a pure mathematical sense
that assumes you know the values of
the initial numbers exactly. That is, that
3.7 is actually 3.7000000000..., that
1.378 is actually 1.378000000000... and
so on. In the real world when we make
measurements of anything, the value
we get is not known exactly, but rather
has some uncertainty associated with it.
10 11 12
cm
They report the following values:
Value measured
for length
Student
11.0 cm
11.6283476 cm
11.6 cm
1
2
3
Who is right, who has quoted a value of the
proper accuracy?
(Expected answer:
Student 1 has been overly conservative
because it is possible to estimate how
far between the 0.1 cm marks the edge
of the wood lies.
Student 2 is being impractical, because
it is impossible to estimate such small
distances by eye.
Student 3 has made the best estimate of
where the edge lies. No accuracy is lost
as in case 1, and no unrealistic accuracy
is claimed as in case 2. We've assumed
here that one can measure accurately to
Teachers’ Guide Lesson Plans: Physics

10
one-tenth of the smallest markings on
the ruler—in this case, that means to
the nearest 0.1 cm. This example
illustrates the general concept of
significant figures (hereafter called S.F.)
and the accuracy of the least significant
digit .
So student 3's length measurement of
11.6 cm has 3 S.F., with the least
significant digit in the one tenths place.
Now Student 3 measures instead the
width of the same piece of wood and
finds it to be 5.7 cm. This result has the
same accuracy as the previous
measurement (both are given to the
one tenths place), but only has two S.F.
Activity 1
Ask students to measure the length of
their physics book.
Tell the students to discuss with their
neighbour student about the length of
the book and take three readings and
find the significant digits in the final
reading.
As a whole group, share ideas and
problems.
Development
Then explain to the students, if a
student measures the length of a book
as 18 cm. the number of significant
figures in his/her measured values are
two. In the figure 18, the left digit 1 is
the accurately known digit. That is the
student claims it neither to be 0 nor 2.
However for the rightmost digit 8, the
student is not very much confident. This
digit may be regarded as a doubtful digit
as it may be 7 or 9 instead of 8. Thus a
number may consist of two types of
digits.
a) Accurately known digits and
b) doubtful digit
In any number all the accurately known
digits and the first doubtful digit are
called the significant figures.
Let another student measures the same
book using a ruler and claims its length
to be 18.5 cm. In this case the student is
sure about the digits 1 and 8. 1 and 8 are
accurately known digits. However
he/she has doubt about the last digit in
his/her measurement as he/she regards
18.4 cm or 18.6 cm to be as accurate as
18.5 cm. Thus the last digit 5 in his/her
measurement is a doubtful digit.
Therefore all the three figures are
significant, the two accurately known
digits and the one doubtful digit.
The precision of a measured value of a
physical quantity is reflected in the
number of significant figures (or
significant digits) used in expressing the
values. An improvement in the quality
of measurement by using better
instruments increases the significant
figures in the measured result and at the
same time reduces the uncertainty of
the result.
Teachers’ Guide Lesson Plans: Physics

Activity 2
Write the following on the chalkboard: A=1.24m B=0.23cm. Ask students which
measurement has more significant digits
Explain to students that A has three significant digits and B has only two significant digits,
however, A is a measurement to the nearest centimeter, but B is a measurement to nearest
1/100 centimeter. It is more precise.
11
Activity 3
Measuring a Piece of Metal Width with a Ruler Showing Centimeters, divided the class in two
groups by saying you are measuring the width of this piece of Metal with a ruler that only showed
centimeters (cm).
6 7cm
6.5 6.6
(not actual size)
The ruler shows centimeters so we’re
allowed to estimate one more
decimal place than cm-in other words
to tenths of a cm.
The piece of Meatal looks to be around 6.5 or 6.6 cm
We can estimate this piece of Metal's
width as, for example: Studetn from
Group 1
1 place past cm.
6.5 cm
We cannot estimate this piece of
Metal's width as, for example: Studetn
from Group 2
1 place past cm.
6.6 cm
2 places past cm.
6.57 cm
2 places past cm.
6.58 cm
OR OR
The last digit is significant but uncertain
and is in the tenths place.
Note: Technically we could say the width
is 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8,
or 6.9. But 6.4 and 6.5 look the closest to
me.
We're trying to go two decimal places
beyond cm, to hundredths of a cm.
Scientists allow estimates this accurate
using this particular ruler.
2 significant figure
are allowed here.
3 significant figure
are NOT allowed.
Teachers’ Guide Lesson Plans: Physics

40
30
20
32.0
12
Conclusion/Sum up
It is true of science in general and of physics in
particular that its essence is measurement.
No fact in science is accepted, no law
established, unless it is qualified
measurement.
The accurately known digits and first doubtful
digit in any measurement is called significant.
Number of significant figures depends
i. Size of the object
ii. Degree of approximation and
iii. Measuring instrument: for example
In case of metre rod/ruler having signs of cm and
mm, the accuracy of measurement is upto one
millimeter (1mm). In case of a varnier caliper with
least count of 1/10 mm, the accuracy will be 1/10
of a mm.
In case of Micrometer screw gauge with last count
of 1/100 mm, the accuracy will be 1/100 of a mm.
Greater the accuracy of the instrument, the larger
the number of significant figures that can be
used: the measurements recorded as:
(I) 2.4
(ii) 2.40cm &
(iii) 2.400cm specify the use of different
instrument.
Non-zero digits are always significant.
All final zeros after the decimal point are
significant.
Zero between two other significant digits is
always significant.
Zeros used solely as place holders are not
significant.
Assessment
1- State the number of significant digits in each
Follow-up
Why does a vernier calipers gives more
accurate reading than as a measuring tape?.
Why it is needed to two round of numbers at the
end of calculations?
Why does a vernier calipers gives more
accurate reading than as a measuring tape?.A
sporting goods store is advertising a breakthrough
in stop watches. The new model can measure to
1/1000 of a second. Ask students to write a
paragraph explaining whether such a watch would
be useful. (hint: Students should realize that this
watch is a triumph of technology but that it
doesn’t make any sense to buy such a watch when
the human reaction time is about 1/10 second.
Solve all the questions given at the end of the
chapter
measurement. Answers
a. 245 m 3
b. 0.00623 gm 3
c. 1.86000 x m 3
5
10
5
d. 1.86 x 10 m 6e. 308 km 3
2- Identify the correct number of significant
digits in each number.a. 0.234 three
b. 112000 three
c. 13.067 five
d. 2.450 four
3- Ask students to record their reading from the
given diagram and suggest t he correct
number of significant figure. (correct reading
32.0)
Teachers’ Guide Lesson Plans: Physics

Identify various types of graphs
Draw and display given data in the form of a
graph
Recognize linear direct and inverse
relationships
Interpret a graph by describing the
information provided by it
Students’ Learning Outcomes
13
Information for Teachers
Drawing & interpreting graphs is one of the
important skills applied not only in
Drawing and Interpreting Graphs222
UNIT
T O P I C
Kinematics
Lesson Plan
3
Grade IX
mathematics and sciences but also in all other
disciplines of social sciences, commerce,
business studies etc.
Graphs make visual display of data and other
numerical information readable easily.
A Graph gives visual pictures of results and
information regarding relationship between
two variable quantities.
It can be used to find an average value from a
set of readings.
It can be used to find value of a quantity which
is not actually observed experimentally.
It helps to discover error in the experimental
observations.
10 20 30 40 50 60
100
10
d(t)
t
d(t)
t
Teachers’ Guide Lesson Plans: Physics

14
Activity 1
Arrange to show various types of graphs mentioned below taken from Newspapers /
Magazines to initiate discussion on graphs.
1. Bar Graph 2. Line Graph 3. Circle (or Pie) Graph
1. BAR GRAPH
i) A bar graph is used to show relationship between groups that are not continuous.
ii) The two items being compared do not need to affect each other.
iii) Numerical values are shown in bars of varying lengths.
iv) Easy to see the comparison of two items
v) Multiple comparisons are possible
To make a graph:-
1. Use a suitable scale 2. Label axis and plot data
3. Choose a title representing the data
A B C D E
Average
Height
in cm
The Effect of Fertilizers on Bean Plant Growth
Figure 1
0.0
2.8
5.6
8.4
11.2
14.0
16.8
19.6
22.4
25.2
28.0
2. LINE GRAPH
I) A line graph is made from pair of numbers. Each expresses a relationship between two
variables.
ii) It shows a continuous variation of one quantity affected by another.
iii) Line graph shows the effect of independent variable on a dependent variable.
iv) It reflects comparison easily.
v) Reveals trends of pattern and relationships between data.
vi) Widely used in statistics and science.
Duration/Number of Periods
160 mins/4 period
Material/Resources Required
Meter stick, String, four Circular objects, Graph
paper, Pictures
Introduction
Teachers’ Guide Lesson Plans: Physics

15
Sohail: 36 year old office worker
Ahsan: 26 year old former college athlete
Time (in Minutes)
Exercise and Pulse Rate
Pulse
Rate
in
Beats
per
Minute
0
16
32
48
64
80
96
112
128
144
160
Figure 2
3. CIRCLE (OR PIE) GRAPH
i) A circle graph is used to show how part of something relates to the whole.
ii) This kind of graph is needed to show percentages effectively.
iii) To draw a pie chart:-
Find the percentage of each type

o
Find the size of wedges that make up the pie chart by multiplying each %age by 360 . (since a
o
circle contains 360 .)
Use compass to draw a circle.
Use protractor to draw required angles.
Finally, label each part of the chart and choose one appropriate title.
iv) This type of graph is a circle divided into segments.
v) Each segment represents a particular category.
vi) Lay out largest portions first in clockwise position.
vii) Label larger portion in the circle; smaller outside with connecting lines.
Figure 3
Vanilla
Chocolate
Strawberry
Respberry
Peach
Neopoliton
Other
Flavour Liking of Persons
21.0%
33.0%
12.0%
4.0%
7.0%
17.0%
6.0%
An Ice Cream Survey
Teachers’ Guide Lesson Plans: Physics

16
Activity 2
Now tell the students how graph is plotting
PLOTTING A GRAPH
Every Graph shall have:
(a) A title: On top of the sheet such as
“Load against Extension”
(b) Axes to be labeled: Normally cause
(independent variable) on X-Axis
and the effect (dependent variable)
on y-axis but it is not essential. Write
clearly the name of each variable
giving its unit [Fig.5].
Title
Label/Unit
ordinate
or y-axis
Label/Unit abscissa or x-axis
Scale for y-axis
Scale for x-axis
Figure 4
( c) Suitable scale: Do not condense the
graph into a small area but make it
fill the whole sheet. This requires a
suitable scale for each axis [Fig.5].
Draw a graph as large as the
available space allows. Scale should
have 0, 1, 2, 3 ---- or 0, 2, 4, 8 ---- or 0,
5, 10, 15 sequence. Odd sequence
such as 0, 3, 6, 9 — or 0, 7, 14 should
not be used.
(d) Selected scale to be mentioned:
Same scale on both axes not
essential. Even zero of the scale not
necessarily to lie on the origin
[Fig.5].
(e) Graduation: Make scale on each
axis not the actual number.
(f) Points to be plotted with: Cross (x or
+) or with dot and circle ( ) [Fig 5].
Load against Extension
Scale 2 cm = 0.5N
Scale 2 cm = 20mm
Load
L (N)
Extension e (mm)
Figure 5
(g) Drawing curve: The plotted points
must be joined with single straight
line. Do not attempt to join all points
on the graph .If the points do not
seem to lie on a straight line, draw a
free hand smooth line (continuous
curve) passing evenly through most
of the points.
(h) Best straight line: Try to draw a
straight line which passes through
as many of plotted points as
possible or which leaves on equal
distribution of points on either side
(Figure 6).
a. A transparent ruler is very useful for
drawing this line.
b. Statistical Method: simply mark
with different notation, the mid
points for each pair of plotted
points. The mid points usually lie
nearly on a straight line. The process
usually can be repeated until a
straight line is obtained.
Teachers’ Guide Lesson Plans: Physics

17
(I) Conclusion: State and display the
conclusion drawn from the graph. In
the given example, a straight line
graph through the origin confirm
that extension in length is
proportional to applied load (Fig.5)
STRAIGHT LINE GRAPH
It is often useful to plot experimental data in
such a way that straight line graph results.
From the straight line graph OA, by
completing right angled triangle line OAM,
Figure 6
y
x
0
Tanθ
AM
OM
=
y
x
=
m
y
x
=
ymx=
M
A (x,y)
y
O
x
Figure 7
Let Tan θ = m (Slope or Gradient of the line)
Then
Or
which is linear equation of a straight line
through the origin. It means y is directly
proportional to x, where m is content. If
straight line does not pass through the
origin than y = mx + c where c is the
intercept on y axis.
Examples: The relations of this type are of
Ohm's law & Hooke's law.
Slope and Intercept
Gradient (slope) of a straight line is the
tangent of the angle θ which the line make
with the horizontal. In case of Pd 'V' and
current 'I' the slope of the line gives the
resistance. The slope m in the above
equation is the ratio of vertical change to
the horizontal change. For that purpose
select two points A and B, as far apart as
possible on the graph line. The vertical
change ∆y is the difference between the
vertical values of A and B. The horizontal
change ∆x is the difference between
horizontal values of A&B. The Slope m = ∆y /
∆x
Figure 8
B
V
O
A
I
y
y
2
x
∆
x
∆
y
1
x
1 2θ
θ
Evidence of how a reading is taken from the
graph must be shown. e.g. (a) The triangle
for calculation of gradient (b) reference line
Teachers’ Guide Lesson Plans: Physics

18
(broken lines) to fine a point on the
horizontal axis corresponding to a point on
the vertical axis or vice-versa.
Intercept: It is the point at which graph line
crosses the y-axis known as y intercept.
Inverse Relationship:
Another common situation occurs when
one quantity varies inversely with other
quantity y = k/x, the graph of such
relationship is a hyperbola (Fig 9).
Figure 9
V
P
T = Constant
Total Pressure P as a Function of
Volume V for Gas
Quadratic :Relationships
Sometimes a quantity varies as the square
2
of some other such as y = ax. The equation
of this type is known as a quadratic equation
and its graph is a parabola (Fig.10).
0 5 10 15 20 25 30
20
40
60
80
0
Figure 10
Braking Distance (m)
Original Speed (m/s)
Braking Distance Versus Original Speed
Activity 1
Ask students to make a list of direct
relationship and inverse relationship.
Discuss their responses in the class.
Development
Activity 2
Use a meter stick to measure the
diameter of four circular objects and
a string to measure their
circumference.
Record your data in a table.
Make graph, the circumference
versus the diameter.
What type of relation is shown by the
graph between circumference and
diameter?
Could a different straight line
describe a different circle?
Conclusion/Sum up
 A graph in which data points lie in a
straight line is a graph of linear
relationship.
 A linear relationship can be expressed by
the equations y = mx + c.
 The slope 'm' of the straight line graph is a
vertical change divided by the horizontal
change.
 The graph of an inverse relationship
between x & y is a hyperbola represented
by the curve y = a/x.
 The graph of quadratic relationship is a
parabolic curve represented by
2
y = ax + bx+c
Teachers’ Guide Lesson Plans: Physics

19
Assessment
1. A student performing an experiment with the
simple pendulum determined the time period
'T' for various lengths 'l' of the pendulum. The
data is tabulated below:
2
i. Plot a graph with 'l' along the x-axis and T
along the y-axis using a suitable scale.
ii. Which variable is dependent variable?
iii. From the graph, determine the value of 'l' for
second's pendulum.
2. In an experiment the value of g was
determined by free fall method. It was
observed that the distance of fall (S) of the
bob from its initial position and the
corresponding time period (T) of the rod have
a certain relation. A few values of S and the
2
corresponding time period square T are
tabulated below:
i. Plot a paragraph between a taken along
2
abscissa and T taken along ordinate.
ii. Find the slope of the graph.
iii. In case of free fall, what does this slope stand
for?
1.961.911.811.271.00.6
2
T
2
(s )
858075706560l(cm)
Distance,
S (cm)
Time Period
2 2
squared T (S )
0.65
20 30
0.95
40
1.30
50
1.55
60
1.90
Follow-up
1. A student performing an experiment with the
helical spring obtained the following data for
loads 'L' and the corresponding extensions∆ x.
i. Draw a graph between 'L' taken along x-axis
and '∆ x' along the y-axis, using a suitable
scale.
ii. Which is the dependent variable?
iii. Determine the spring constant and give its
units.
2. Students will collect different types of
graphical sketches printed in some
Newspapers / magazines and share with
peers the information displayed by them. The
conclusions should be posted on the wall or
softboard in the form of posters.
L (g)
x (cm) 3.4
50 100
6.8
150
12.0
175
13.4
200
16.0
Teachers’ Guide Lesson Plans: Physics

Plot and interpret distance- time graph and
speed- time graph.
Determine and interpret the slope of
distance – time and speed- time graph.
Determine from the shape of the graph the
state of a body when it is:
1. At rest
2. Moving with constant speed
3. Moving with variable speed
Students’ Learning Outcomes
20
Information for Teachers
We can represent the changing position of a
moving object by drawing a distance-time
graph.
The slope of the graph tells us about its speed.
The steeper the slope, the greater the speed
is.
We must assume that the object is moving in a
straight line.
Graphical analysis of Motion
222
UNIT
T O P I C
Kinematics
Lesson Plan
4
Grade IX
Time Period
Constant Velocity
Displacement
Teachers’ Guide Lesson Plans: Physics

21
The straight line shows that the object is moving
steadily; its velocity is constant.
Distance - time graph
(I) As a convention, we usually start from the
origin, i.e. S = 0 when t = 0.
(ii) The slope tells us which object is moving
faster. The steeper the slope, the greater the
velocity.
(iii) The slope of this graph is 0.
Displacement s is not changing.
Velocity v = 0. The object is stationary.
(iv) The slope of this graph suddenly becomes
negative. The object is moving back the way it
came. Its velocity v is negative.
(v) This displacement - time graph is curved. The
slope is changing. This means that the object's
velocity is changing.
Speed-Time graph
The slope of the speed-time graph tells us
whether the speed has been changing at a
high rate, at a low rate, or not changing at all.
Acceleration is deduced from the slope of
speed-time graph.
Acceleration = gradient of speed-time graph.
(I) A straight line shows constant acceleration
(ii) The greater the slope, the greater the
acceleration
s
t
greater speed
low
er speed
s
t
s
t
s
t
s
t
v
t
gr
eat
er
accelera
tion
lower acceler
ation
v
t
Teachers’ Guide Lesson Plans: Physics

22
(iii) A negative slope shows declaration (a is
negative)
(iv) The slope is changing; the acceleration is
changing
Duration/Number of Period
80 mins/2period
Material/Resources Required
Graph paper, pencil, rubber, sharpener, ball,
chart papers, showing pictures
Introduction
Activity 1
Ask students about various ways to present
data. From the feedback of students,
highlight the importance of graphs as an
alternate method to represent the motion
of the body graphically and to solve
problems of motion / or visualizing the
relationship between the physical
quantities.
Activity 2
Students will be asked to conduct
experiment and following points can be
used as guidelines:
Ask your classmate to throw a ball
vertically upwards and observe the
motion of the object.
Is its initial speed zero?
At the highest point of its journey, what
is its speed? What do you think its
acceleration at that point?
What can be the source of error in this
activity?
Try sketching the speed-time graph to
describe the motion of the ball from the
time it is thrown upwards to the
moment your classmate catches it
again.
Activity 1
We can calculate the speed of an object
at different times during its journey
using a distance-time graph.
The distance-time graph below shows
the journey of a cyclist
Possible Answers to Teacher
Have the students describe motion from
A to B, B to C, C to D and form D to E. they
should also calculate speed during each
interval.
Between B and C the cyclist is travelling
more quickly away from his starting
point. His speed during this part of his
journey is distance travelled / time
Development
v
t
v
t
Distance from start
300m
200m
100m
50s 90s 150s 180s
A
C D
E
B
Teachers’ Guide Lesson Plans: Physics

23

Activity 2
Ask the students to describe the motion
for A to B, B to C, C to D, D to E and for E
to F. Tell them also calculate the
acceleration during each interval.
Help them if needed.
Possible Answers for Teachers
Between A and B the runner travels at a
constant speed of 5 m/s for 10s.
There is no change in his velocity so his
acceleration is zero.
Between B and C he takes 5s to slow
down and stop. His declaration during
this part of his journey is change in
2
velocity / time taken = 5 / 5 1 m/s .
Between C and D he remains stationary
for 10s. His acceleration is again zero.
Between D and E he increases his speed
to 10 m/s in 5s. His acceleration during
this part of his journey is change in
2
velocity / time taken = 10 / 5, 2 m/s .
Between E and F he travels at constant
velocity of 10 m/s for 5 s and his
acceleration is zero.
Activity 3
 Draw t he following distance-time
graph and table on the board.
 Ask the students to fill the descriptions
in the table.

Possible answer for teachers only
Activity 4
Interpreting a Speed – Time Graph
Below is a speed-time graph that describes
the motion of an object over 70s.
Which part(s) of the graph show(s) that the
object is
a) At rest?
b) Moving with uniform speed?
c) Moving with uniform acceleration?
-1
d) Speed/m s
d) Moving with non-uniform acceleration?
10m/s
Spent
5m/s
50s 90s 150s 180s
A B
D
E F
C
20
Spent
10
5 10 15 20
A
B
D
Edistance (m)
C
D
time/s
0
0
taken = 200m / 40s = 5m/s.
Between C and D the Cyclist has
stopped.
Between D and E the cyclist is travelling
very quickly back towards his starting
point. His speed during this part of his
journey is distance =
300 - 0 300
= 10ms
-1
180 - 150 30
=
(A) 0s
(B) 5s 10s
(C) 10s 15s
(D) 15s 20s
(E) at t = 20s
5s
Graph
To
t =
Description
From
t =
(A) 0s
The object start from rest
and moves with constant
speed of 2 m/s
(B) 5s 10sThe object is at rest (0 m/s).
(C) 10s 15sThe object moves with
increasing speed
(D) 15s 20s
The object moves with
decreasing speed
(E) at t = 20s
The speed of the object
is more than 20 ms
5s
Graph
To
t =
Description
From
t =
-1
Teachers’ Guide Lesson Plans: Physics

24
Possible answers
Comparison of distance-Time and Speed-Time graphs for a body:
1. At rest
2. Moving with constant speed
3. Moving with variable speed
(A) 0s
10s

The object accelerates from rest (0 m/s) to 5 m/s with a constant
acceleration 0.5 m/s
2

(B)

10s
20s

It is moving at a constant speed of 5 m/s.

(C)

20s

30s

It increases its speed from 5 m/s to 12 m/s with an increasing
acceleration

(D)

30s

40s

It increases its speed from 12 m/s to 15 m/s with a decreasing
acceleration.

(E)

40s

50s

It is travelling at a constant speed of 15 m/s.

(F)

50s

60s

The object decelerates from 15 m/s to 3 m/s with a constant
deceleration 0.5 m/s
2

(G)

60s

70s It decreases its speed from 3 m/s to 2 m/s with a decreasing declaration.

Graph Description
t=
To
t=
From
At rest
gradient=0
Distance
Time

Speed

Time

Gradient= 0
Speed = 0
Motion of object Distance-time graph Speed-time graph
15
10
0
time/s
20 30 40 50 60 70
10
5
(A)
(B)
(C)
(D)
(E)
(F)
Speed/ms
-1
Teachers’ Guide Lesson Plans: Physics

25
Moving with uniform
speed
Distance

Time

Gradient constant Gradient = 0
Speed

Time

Moving with uniform acceleration
Time

Distance
Gradient varying

gradient constant
Speed

Time

Assessment
1. Analyzing motion of a body at A, B, C and D
with the help of Distance-Time graph.
2. Show the s-t graph of a stone projected
vertically upwards at 40 m/s.
a) How long does it take the stone to reach its
highest point? (Ans: 4 s)
b) What is the greatest height reached? (Ans:
80m)
c) What is the time of flight? (Ans: 8 s)
Follow-up
Plotting the Speed-Time graph and answering
short question based on that graph
The table below shows how the speed of a car
varies with time.
Time
/s
0123 4 567

8 9 10
Speed
/m
s-1
05101520 25 30 30 30 30 30
a) One the axes provided below, plot a graph of
speed against time.
b) (i). Calculate the total distance travelled by
the car at the end of 30 s.
(ii) Hence calculate the average speed of
the car.
A
B
C
D
distance/m
time/s
1 2 3 4 5 6 7 8 t (s)

S(m)
80
60
40
20
Teachers’ Guide Lesson Plans: Physics

Students will be able to:
define moment of force or torque as
moment = Force x perpendicular distance
from pivot to the line of action of force.
explain the turning effect of force by
relating it to everyday life.
state the principle of moments.
define the center of mass and center of
gravity of a body.
Students’ Learning Outcomes
26
Information for Teachers
Moment of a force or torque is the turning
effect of a force.
Torque depends upon the magnitude of force
and the perpendicular distance of the force
from the pivot.
It is easier to tighten up a nut with a spanner,
to open the cap of a bottle with opener, to
open the door from the knob rather than near
the hinge. All these examples give rise to the
Moment of a Force444
UNIT
T O P I C
Turning Effect of forces
Lesson Plan
5
Grade IX
M
d
F
Force
Moment
Distance
Teachers’ Guide Lesson Plans: Physics

27
turning effect of forces.
There are two types of moment of force.
a. Anticlockwise moments
b. Clockwise moments
Principle of moments states that when a body
is in equilibrium the sum of clockwise
moments and anticlockwise moments about
any point is zero.
Center of gravity is that point where the
whole weight of a body appears to be acting.
The forces which have same direction are
called like parallel forces and the forces which
have opposite directions with each other are
known as unlike parallel force.
When two equal and opposite parallel forces
act on a body on two different points they
produce torque in the body and the pair of
such forces is called couple.
Bicycle pedal, car steering, water tap knob
and cross spanner are some examples from
daily life in which couple of forces make them
to rotate.
There is no difference between center of mass
and center of gravity as long as 'g' remains
same over the system.
Moment of Force or Torque
Anticlockwise Clockwise
=
Principle of Moments = F x d
Calculated by
Duration/Number of Periods
80 mins/2 period
Material/Resources Required
Metre rule, wedge, a chart having drawings of
different objects etc.
Introduction
Activity 1
Get three students and ask them to balance
a metre rule on their finger tips turn by turn.
Each student will make the metre rule
balanced on his finger after a little effort.
Now introduce the students the concept of
C.G by telling them that the point where the
body gets balanced is the C.G of the bodies.
Activity 2
Choose two students with half metre rules.
Ask them to hold the metre rules from the
ends. Ask one student to release the both
ends of the metre rule simultaneously. The
metre rule falls freely. Now allow the other
student to release only one end of the
metre rule, the rule swings down around
the other end. After this activity introduce
the students about the turning effect of a
force and the axis of rotation.
Teachers’ Guide Lesson Plans: Physics

28
Activity 3
Get a student to open the class-room door
as usual. Ask him to open the door by
pushing near the hinge. Close the door and
again let him open it by pushing the knob.
Now ask him, where he realizes difficulty in
opening the door? Get this activity by few
more students. Note their response on the
board. Now introduce the concept of
moment arm and how it affects the torques.
Activity 4
Draw the following diagram of sea-saw on
the board in which two students of equal
weight are sitting at the same distance from
the pivot.
Call one of the student to show the
direction of moment of force by drawing an
arrow head for both the students enjoying
sea saw. From this activity introduce the
concept of anticlockwise and clockwise
moments. Tell the students that when both
the clockwise and anticlockwise moments
cannot make the sea-saw rotate then they
are equal. Now state the principle of
moments for a body to be in equilibrium as:
Anticlockwise moments = clockwise
moments
After these activities ask the following
questions to the students
i. What is moment of force?
ii. What is the formula to calculate
moment of force?
iii. What are the possible types of
moments
Expected answers:
i. Turning effect of a force
ii. = F X d
Clockwise and anticlockwise

Activity 1
Draw a diagram of three spanners of
different lengths opening a nut.
Development
10N
d=8cm
12N
d=6cm
8N
d=10cm
Ask the students to calculate the moment
of force from the given data.
Spanners

Force

Moment arm
1 10 N 8 cm
2

12 N

6 cm

3 8 N 10 cm
Which spanner can move the nut more
easily? (Expected answer: spanner 1
and 3)
Why spanner with 10 N and 8 N forces
Teachers’ Guide Lesson Plans: Physics

29
produce the same moment? (Expected
answer: as both the spanners have
same moment of force)
Which spanner would you like to use?
Expected answer: Spanner 3
Activity 2
Show the chart to the students on which the
following diagrams with pivot, applied force
and the perpendicular distances are drawn.
Ask various students to indicate the types of
moments; clockwise or anticlockwise in
each diagram and record their answers on
the board.
Expected Answers:
1. Clockwise
2. Clockwise
3. Clockwise
4. Anti-clockwise
5. Anti-clockwise
6. Anti-clockwise
Fig: 1
effort
Fig: 2
Fig: 3
Effort
Fig: 4
effort P
load W
effort P
load W
Fig: 5
effort P
Fig: 6
spoon
Tin can
lid
Teachers’ Guide Lesson Plans: Physics

30
Activity 3
To investigate the principle of moments
Help the students to set the metre rule
balanced on a wedge.
Take two weights of 50g mass (W ) and
1
100g mass (W ) and tie them with
2
thread loops.
Hang these weights with the help of
loops on both sides of the metre rule
and balance the system by adjusting
their distance from the pivot.
Now change the positions of the weight
so that the system is balanced again.
When the metre rule is balanced, ask the
students to calculate the clockwise and anti
clockwise moments. Are these moments
equal.
Conclusion/Sum up
Moment of force is the turning effect of force
and is the product of force and moment arm.
Anti clockwise moments = clockwise
moments.
There is no difference between center of mass
and center of gravity as long as 'g' remains
same over the system.
Follow-up
Go with your parents in a nearby children park
on the coming Sunday and enjoy sea-saw with
your brother or sister and observe the effect
of moment arm in swinging sea-saw and
search different distances from the pivot to
get the same swing each time.
Solve all the problems about torque and
principle of moments given at the end of the
chapter/unit.
Teachers’ Guide Lesson Plans: Physics
Assessment
Q.1 how is it possible for a young boy to enjoy
see-saw with his father although he is
much lighter than his father. (expected
answer: The young boy and his father may
enjoy see-saw by producing equal and
opposite moments. This can be achieved
simply by adjusting their arm lengths.)
Q.2 Is it possible for a body to be in
equilibrium under the action of a single
force? (expected answer: A body can
never be in equilibrium under the action
of a single force. A counter force in
necessary required for the body to keep in
equilibrium.
Q.3 what is the difference between centre of
gravity and centre of mass? (expected
answer: There is no difference between
center of mass and center of gravity as
long as 'g' remains same over the system.

Students will be able to:
define equilibrium and classify its types by
quoting examples from everyday life.
state two conditions of equilibrium of a
body.
Students’ Learning Outcomes
31
body at rest will remain at rest and a body in
motion will remain in motion with uniform
velocity. In both cases we say that the body is
in equilibrium. In the first case the body is said
to be in static equilibrium while in the second
case it is said to be in dynamic equilibrium.
A book laying on a table, an electric bulb
hanging from the ceilings of a room are the
examples of the bodies which are in static
equilibrium.
Falling paratroopers, a moving vehicle with
uniform velocity, rotation of earth are the
Equilibrium444
UNIT
T O P I C
Turning Effect of forces
Lesson Plan
6
Grade IX
Information for Teachers
When a number of forces act on a body and
the resultant of these forces is zero then a
Teachers’ Guide Lesson Plans: Physics

32
examples the bodies which are in a dynamic
equilibrium.
There are two conditions for a body to be in
complete equilibrium. First condition states
that the body will be in equilibrium if the
vector sum of all the external forces acting on
a body is zero.
F + F + F + …………………….. + F = 0
1 2 3 n
 F = 0
Second condition of equilibrium states that
the body will be in equilibrium if the algebraic
sum of all the torques acting on the body is
zero
    + + …………………. = 0
1 2 3 + n
 = 0
A body will be in complete equilibrium if it
satisfies both the conditions.
Introduction
Activity 1
Arrange a tug-of-war contest in which
two teams having three students each
pull the rope towards each other.
Ask all the other students to watch this
contest keenly.
Duration/Number of Periods
80 mins/2 period
Material/Resources Required
board, chalk/marker, rope, card boards, textbook
Both the teams make effort, but no one
team can pull the other and thus the
rope does not move. Knock out a
student from any one of the team and
again start this contest. After a little
effort a team with three students will
pull the rope.
Ask the following questions to the
students.
1. Why both the teams cannot move
the rope in the first contest?
(Expected answer: Both the teams
pull the rope with equal force)
2. Why did the team with three
students pull the rope in the second
contest? (Expected answer:
Because the team of three students
pulls the rope with greater force as
compared to the team comprising of
two students).
After this activity introduce the
students that when forces acting on a
body are equal and having same line of
action they cancel each other and the
body upon which these forces act
cannot move. We say that the body is in
equilibrium. Tell the students that the
hanging bulb in the class room and a
book lying on the table are the examples
of the bodies to be in equilibrium. As
these bodies are at rest, therefore, they
are said to be in static equilibrium.
Students are already familiar with
uniform velocity and Newton's first law
of motion. Tell the students that the
bodies in uniform motion are also in
equilibrium, which is called dynamic
equilibrium.
Teachers’ Guide Lesson Plans: Physics

33
Activity 1 (Board activity)
Draw a table on the board and fill it with the
help of students and ask the students to
copy it on their note books.
Development
Activity 2
Activity 2
Card 1
Card 2
Cut two rectangular card boards and
make two holes on each of them as
shown in figure. Tie the cards from
these holes with two pieces of thread.
Take two students from the class and
give them card-I. Ask them to pull the
free ends of the thread. Both students
pull the thread and the whole class
observe that the card neither moves
linearly nor it rotates. Now give them
the second card and ask them to pull the
free ends of the thread. In spite of
applying equal and opposite forces, the
card does not remain at rest. It moves
clockwise.
Ask the following questions from the
class:
Q.1: What kinds of forces act on the first
card? (Expected answer: Unlike equal
parallel force)
Q.2: What kinds of forces act on the second
card? (Expected answer: Unlike equal
parallel force).
Q.3: Why the card 1 remains at rest while
the card 2 rotates? (Expected answer)
a. In card 1, forces act along the same
line and no torque is produced.
b. In card 2 forces do not act along the
same line and thus a torque is
produced.
At the end of this activity tell the
students that although both the cards
were satisfying first condition of
equilibrium even then the card 2 was
not in equilibrium. Therefore, second
condition is also necessary for a body to
be in complete equilibrium. Write the
second condition of equilibrium on the
board.
No. Objects
Type of
equilibrium
1.
2.
3.
4.
5.
A man sitting in a chair
Falling of paratrooper
A moving car with
uniform velocity
Rotation of Earth
A hanging lamp
Expected answer
No. Objects
Type of
equilibrium
Static
equilibrium
Dynamic
equilibrium
Dynamic
equilibrium
Dynamic
equilibrium
Static
equilibrium
1.
2.
3.
4.
5.
A man sitting in a chair
Falling of paratrooper
A moving car with
uniform velocity
Rotation of Earth
A hanging lamp
Draw the following diagrams and the
table on the board.
Ask the students to copy and fill the
table about satisfying the 1st and 2nd
condition of equilibrium.
Teachers’ Guide Lesson Plans: Physics

34
Fig 1
st
About 1 condition
of Equilibrium
Objects
nd
About 2 condition
of Equilibrium
About complete
Equilibrium
Fig 2
Fig 3
Fig 4
Fig 1 Satisfied
st
About 1 condition
of Equilibrium
Objects
nd
About 2 condition
of Equilibrium
About complete
Equilibrium
Fig 2 Satisfied
Fig 3 Satisfied
Fig 4 Satisfied
Satisfied Body is in equilibrium
Not Satisfied Body is not in equilibrium
Satisfied Body is in equilibrium
Not Satisfied Body is not in equilibrium
Conclusion/Sum up
A body is in equilibrium if it satisfies both the
conditions of equilibrium:
a. A body will be in equilibrium if the algebraic
sum of all the forces acting on it is zero
b. A body will be in equilibrium if the algebraic
sum of all the torques is zero.
Assessment
Ask the following questions to assess the students
learning.
Q.1: How does a paratrooper gain its dynamic
equilibrium? (Expected answer)
o When a freely falling paratrooper opens
parachute, his weight and air friction
balance each other and he starts to fall with
constant velocity and thus gains a dynamic
equilibrium.
Q.2: How can you find the weight of a meter rule
without using physical or spring balance?
(Expected answer)
o Balance the meter rule at the point other
than C.G with the help of a given weight.
Now by applying the principle of moments
the weight of the meter rule can easily be
found.
Follow-up
Identify two examples in which single force is
used to turn the object
Identify two examples of the objects in which
two forces are used to turn them.
Solve the problems given at the end of the
chapter.
Expected response of the students will be as.
Fig 1
Fig 2
F
F
Fig 3
F FFig 4
F
1 F
1
F
2
F
2
Teachers’ Guide Lesson Plans: Physics

Students will be able to:
Describe to states of equilibrium and
classify them with common examples.
Explain effect of the position of center of
mass on the stability of simple objects.
Students’ Learning Outcomes
35
Information for Teachers
b. Unstable equilibrium
c. Neutral equilibrium
The equilibrium of the bodies is affected by
the position of center of mass or center of
gravity.
A body will be in stable equilibrium if on
slightly disturbing, its center of gravity is
raised up as compared to the initial position.
If on slightly disturbing, the C.G of the body is
lowered as compared to its initial position the
body will be in unstable equilibrium.
If on slightly disturbing, the C.G of the body
Stability444
UNIT
T O P I C
Turning Effect of Forces
Lesson Plan
7
Grade IX
There are three states of equilibrium
a. Stable equilibrium
Teachers’ Guide Lesson Plans: Physics

36
neither lowers nor raises but keeps the same
position then the body will be in neutral
equilibrium.
Stability plays an important role in our daily
life. It is an important factor which is kept in
view in architecture and manufacturing the
bodies of the vehicles.
Unstable objects may lead to severe
accidents, causing great loss of property and
lives.
New C.G.
C.G.
New C.G.
C.G.
Activity 1
Draw the following diagrams and the table
on the board.
Development
Introduction
Activity
Take a pencil, a wooden block or a board
duster and a ball.
Mark their center of gravity carefully
with red marker.
Place the block with rectangular base
and ask a student to keep a scale vertical
along its one of the edge and note the
position of its C.G.
Ask the other student to lift the block up
from one side and again note the position of its C.G. Now release the
block. It will come to its initial position. Write the following questions on the
board.
Q.1: What happen with the C.G when the
block was lifted? (Expected response:
The C.G was raised.
Q.2: What happened with the block when
it was released? (Expected response:
It came to its original position.
Now generate the concept that when a
body is slightly disturbed and its C.G raises
as compared to its initial position, the body
is in stable equilibrium.
Repeat this activity with pencil standing
erect as well as a rolling ball and develop the
concept for unstable and neutral
equilibrium by asking the same questions as
given above.
New C.G.
C.G.
C.G. C.G.
C.G.
Duration/Number of Periods
80 mins/2 period
Material/Resources Required
Wooden block, ball, pencil, a stiff cardboard, a
pair of scissors, sticky tape, common pins.
Teachers’ Guide Lesson Plans: Physics

37
No.
State of
Equilibrium
No.
State of
Equilibrium
1. 4.
2.

5.

3. 6.
The expected answers:
No.
State of
Equilibrium
No.
State of
Equilibrium
1. Stable 4. Unstable
2.

Unstable

5.

Stable
3. unstable 6. Neutral
Activity 2
Ask the students to investigate that
lowering of C.G makes the bodies
balanced. Help the students in
performing this activity.
Cut the stiff card board in the shape of a
bird as shown in figure.
Ask the students to find C.G of the card
board with the help of plumb line. Guide
the students that C.G. of this bird
shaped cardboard will be near to the
neck.
Fix a pin at its beak and tape the coin,
underneath the wings of the bird near
the tips. Does it stay at its beak; if not try
to adjust the position of the coins again.
When the position of the coins is 
correctly adjusted the bird will become
stable on its beak. Now if it is slightly
disturbed then after swinging, it will
again become stable. On completing
this activity ask the following questions
to the students.
Q.1: What happened to the C.G when the
coins added to the wings of the bird?
(Expected answer: Lower the position
of C.G)
Q.2: How do you think that you could make
the bird even more stable? (Expected
answer: By increasing the equal
number of coins on both sides.
1 2 3
4 5 6
Conclusion/Sum up
There are three states of equilibrium which
depend upon the position of C.G of the
bodies.
Stability plays important role in manufacturing
vehicle bodies, toys and in architecture etc.
Teachers’ Guide Lesson Plans: Physics

38
Follow-up
Why is it possible to balance a metre ruler at
its midpoint but it is not possible to balance
a billiard stick at its mid point? Explain.
Visit a toy shop and identity the balancing
tricks in
a. Self righting toys
b. Racing toy cars
c. Rocking chairs
Solve all the problems gives at the end of the
chapter.
Teachers’ Guide Lesson Plans: Physics
Assessment
Q.1: What are the factors that affect the
stability of an object?
Expected answer:
I. Position of centre of gravity
ii. Area of the base
Q.2 Why is it dangerous to load the roof of an
empty mini bus too heavy? (Expected
answer: On a little tilt the line of action of
the loaded bus will come out of the base
and the bus may topple.
Q.3: Why hanging objects are stable?
(Expected answer: Because the centre of
gravity of the hanging bodies is below the
pivot or point of suspension.)
Q.4: Which of these glasses is the most stable?
Explain your answer.
(Expected answer: c
C has the widest base and is heavier at the bottom.)

The students will:
define power and calculate power from
the formula
Define the unit of power “watt” in SI
and its conversion with horse power
Compare personal power developed
for running upstairs versus walking
upstairs using a stopwatch.
Students’ Learning Outcomes
39
Information for Teachers
Power is the rate of doing work.
Power depends upon the amount of work
done and time taken.
Power is calculated using the equation:
The relationship between force and power is
Power = Force x Velocity
Power666
UNIT
T O P I C
Work And Energy
Lesson Plan
8
Grade IX
timetaken
workdone
Power =
timetaken
workdone
Power = or
timetaken
Energy Changed
Power =
sec
N.m
P = F.V
human engine
400 W
washing machine
motor 250 W
small car engine
35 000 W
(35KW)
Land rover engine
65 000 W
(65 KW)
Teachers’ Guide Lesson Plans: Physics

40
Power may also be defined as the product of
force and velocity.
The unit of power is watt (w).
The power consumed or used is said to be one
watt if one Joule of work is done in one
second.
The multiples of watt are
3
Kw = 10 watts
6
Mw = 10 watts
One horse power is the power delivered by a
horse as an engine (746 J/Sec)
o One horse power is about ¾ kw
o One horse power = 746 w
The slope of energy-time graph gives power
Faster your work greater is your power
Second
Joule
watt =
Development
Activity 1
Place four to six books at different
places in the classroom
Ask two students to collect all the books
as quickly as possible
Assign another student to note the time
in which both the students collect these
books
Ask the rest of the class to assess who
has collected first and who is more
powerful than the others
Duration/Number of Periods
80 mins/2 period
Material/Resources Required
Board, chalk/marker, posters of relevant pictures,
stop watch
Energy
time/s
Activity
Recall the previous knowledge by asking
following questions to students
Q: what is the meaning of “work” in
science?
(Work is done when a force makes an
object move).
Q: what is energy?
(Energy is the ability to do work).
After getting responses from students
explain to them that we have never seen
energy, but we have seen what it does.
People who have a lot of energy may
move rapidly or do a lot of work.
Introduce the today's topic, power and
share with them that power is that rate
at which work is done, or energy is
transferred. Its SI unit is watts (w).
Invite one student to derive the unit of
power from its definition on the
blackboard. Guide him/her where needed.
Introduction
Teachers’ Guide Lesson Plans: Physics

41
Ask the students to conclude the activity by explaining that which student took less time to
complete the task is more powerful.
Activity 2
Ask the students to measure your power output
Guide them in following steps
1. Measure your mass
2. Work out your weight
3. Measure height of stairs
4. Calculate work done when you climb stairs
5. Measure time taken to climb stairs by running.
If possible, use a stop watch for timing yourself
6. Calculate your average power
7. Measure time to climb stairs by walking. If possible, use a stop watch for timing yourself
8. Calculate your average power again
9. Compare both average powers and share your observations with your class fellows.
How to measure your power output:S ample Chart
Assume g = 10 N/kg.
How to measure your power output
1. Measure your mass...
... work out your weight
... calculate work done
when you climb stairs
2. Measure height
of stairs...
3. Measure time
taken to
climb stairs...
... calculate your
average power
Example
mass = 40 kg
weight = 400 N
height = .3 m
of
stairs
work = 400x3m
done = 1200J
time = 4 s
taken
average 1200
power 4
= 300 W
=
work
done
= weight x height
lifted
= force x distance
power = work done
time taken
Teachers’ Guide Lesson Plans: Physics

42
Activity 3
In an attempt to prove that Mr. Ubaid is a
very powerful man, he runs up a flight of
steps 5.2m high in time of 6.2s.
a. Calculate the work done against gravity
by Mr. Ubaid if his mass is 80 kg.
b. An average person has an average
power of about 500 W. Justify, with
appropriate working, whether Mr.
Ubaid is a powerful man.
Conclusion/Sum up
Power is the rate of doing work.
Power is calculated using the equation:
timetaken
workdone
Power= or
timetaken
Energy Changed
Power=
800 J
work done
2 s time
taken
400 w
power output
The power consumed or used is said to be
one watt if one Joule of work is done in one
second.
One horse power is the power delivered by a
horse as an engine (746 J/Sec)
o One horse power is about ¾ kw
o One horse power = 746 w
To determine your power output in running
up a flight of stairs you can measure how
much work you do (in joules) when you go
upstairs by measuring it by your weight in
Newtons (your weight in kilograms x 10).
Divide the work you do by the time it takes to
do it for find out how much power you exert
(in watts)
The quicker you go the more power you exert.
Faster your work greater is your power
Typical power outputs
human engine
400 W
washing machine
motor 250 W
small car engine
35 000 W
(35KW)
Land rover engine
65 000 W
(65 KW)
Assessment
Ask the following questions to assess the
students learning:
Draw a table as shown below put in the
correct values.
Power (watts)
Energy
transferred
(Joule)
Time (Sec)
60
1000
1440
300
1000
5
30
12
Teachers’ Guide Lesson Plans: Physics

43
The cheetah is the fastest creature on
land. A typical cheetah, at full speed, has a
power output of 1000 W. Calculate the
work done by the cheetah in 1 second and
his average power output in 2 seconds.
Follow-up
A 100 W lamp is more powerful than 60W
lamp explaining this statement.
A fat man and thin man ran to the top of hill in
the same times. Who is more powerful? Why?
Compare personal power developed for
running upstairs versus walking upstairs using
a stopwatch.
Ask students to find out how much power
each student can generate.
The students will work in pairs in order to
find the time taken for each student to run
up a flight of stairs. The stairs used are
shown in figure.
a. Make a list of all the readings that
would be needed.
b. Using words, not symbols, write down
all equations that would be needed to
It is estimated that the human brain has a
power requirement of 40 W. How many
joules is that per second?
How many watts are there:
a. in a kilowatt
b. megawatt
c. Horse power
work out the power of a student.
c. Suggest why the total power of the
student is greater than the power
calculated by this method.
Guide the students to solve the problems
given at the end of unit of the test book.
Teachers’ Guide Lesson Plans: Physics

The students would explain
Define the term pressure (as force acting
normally on unit area).
Explain how pressure varies with force and
area in the contact of everyday examples.
Explain that atmosphere exerts a pressure.
Describe how the height of liquid column
may he used to measure the atmospheric
pressure.
Describe that atmospheric pressure
Students’ Learning Outcomes
44
Information for Teachers
Pressure is the ratio of force to the surface
area over which it is exerted or it is the effect
of a force applied to a surface. Pressure is the
Pressure/Atmosphere Pressure777
UNIT
T O P I C
Properties of Matter
Lesson Plan
9
Grade IX
decreases with the increase in height above
the earth's surface.
Explain that change in atmospheric
pressure in a region may indicate a change
in the weather.
Teachers’ Guide Lesson Plans: Physics

45
amount of force acting normally per unit
surface area. The symbol of pressure is p.
The units of pressure are:
1 pascal (Pa) is a pressure of
1 newton per square
metre.

The earth is surrounded by an envelope of air
called atmosphere.
The height of atmosphere is about 300km.
Being matter, air exerts thrust or weight on
earth surface.
5
One atmospheric pressure is about 1.013x10
Pa. We do not feel such a tremendous
pressure because the blood contains

dissolved oxygen at a pressure slightly more
than atmospheric pressure.
Atmospheric pressure decreases with
altitude.
On high altitude some people fall prey to nose
bleeding due to low atomic pressure.
Atmospheric pressure is measured with
barometer.
The miners (worker in mines) face breathing
difficulties in the mines below sea level.
The atmospheric pressure in mines is very
high which causes difficulty in expanding the
lungs.

A
F
p
area
forcenormal
pressure = , =


2
m
N
1Pa 1
Day to day variation in pressure is given by the
lines in weather map. All the places with same
atmospheric pressure is called isobar.
The unit used in weather map is “Bar” and
“millibar”
Pressure depends on force and area.
Teachers’ Guide Lesson Plans: Physics

46
In north region, the wind moves anticlockwise
around the areas of low pressure and clock
wise around areas of high pressure.
Weather changes as the pressure changes,
with low pressure signaling bad weather and
high pressure bringing a settled, fine spell.
Duration/Number of Periods
80 mins/2 period
Material/Resources Required
Blackboard, duster, marker/chalks, chart papers,
scissors, empty oil cans, beaker, straw, syringe,
empty bottle, and balloon
Introduction
Brainstorm with students about force and
pressure
Ask students, why a needle will go through a
piece of cloth, but with the same amount of
force, a pencil will not?
After getting responses from students tell
them that the differently shaped points of the
needle and pencil exert different amounts of
pressure.
Ask the students what is the difference
between force and pressure?
Explain to them when a force acts on an
object it exerts pressure. Pressure acts at right
angle to the object itself, and its strength
depends on the amount of force and the area
over which it is applied. Someone walking on
soft snow will sink into it in normal shoes but
not if they wear snow shows or skis. The
person's weight is the same but snow shoes
spread the weight over a large area this
reduces the pressure. If you wear shoes with
very narrow and pointed stiletto heels then
you may damage the floor surface and leave a
permanent impression or dint. In each of
these examples your weight does not change
but the pressure under your shoes does.
Encourage students to ask you any questions
that they might have on the topic.
Ask students do they know about the
atmosphere
Share the following information about
atmosphere and atmospheric pressure with
students.
Because we have spent all of our lives
living in the atmosphere of the Earth, we
seldom think that we have 20 km or so of
air pressing on us. We do not feel the
pressure because it does not just push
down, it pushes us inwards from all sides.
Our lungs do not collapse, because the
same air pressure flows into our lungs and
presses outwards.
Ask to students what would happen if our
lungs did not contain any air and there
was vacuum inside them.
Teachers’ Guide Lesson Plans: Physics

47
Activity 1
Demonstrate some
effect of air pressure.
Divide the class in
groups of five to seven
students each.
Assign to each group
one of the following investigations
The can crashing experiment
The milk bottle experiment
Sucking
The syringe
G u id e t h em to reco rd t h eir
observations on their observation sheet
and find their inferences.
Call on a volunteer from each group to
share group finding with the whole
class.
Group 1: The can crashing
experiment
Instructions:
o Put a small volume of water in a
metal can and boil the water for
several minutes to drive out most of
the air (Figure a).
o Stop heating and immediately seal
the can with a well-fitting rubber
stopper.
o At the moment you close the can the
steam pressure inside exactly
balances the atmospheric pressure
outside
o As heat is lost from the can the
steam inside condenses and the
inside pressure falls. (Expected
inference: The atmospheric
Development
pressure is now much greater than
the pressure inside the can, so it
crushes the can and makes it
volume very small.
Group 2: The milk bottle experiment
Instructions:
o Fill a milk bottle full of water by
immersing it in a bowl of water.
o Keeping the top of the bottle below
the water surface, lift the rest of the
bottle out of the water.
o The water does not run out of the
bottle. Why?
(Expected result: The atmospheric
pressure P (or air pressure) on the
1
surface of the water balances the
pressure of the water P inside the
2
bottle. If the water began to run out of
the bottle then, without any air in the
bottle P would become less than P. The
2 1
atmospheric pressure will not allow this
to happen).
Teachers’ Guide Lesson Plans: Physics

48
Group 3: Sucking
Instructions
o We think of sucking a drink up a
straw as being a result of our action
rather than an effect of atmospheric
pressure.
o Try sucking a drink up a straw from
an open-topped glass and you will
be successful (a).
o Try sucking the drink out of the
bottle with the closed top (b).
o As there is no air inside this bottle
and no access for atmospheric
pressure, you will not successes in
sucking up much of this drink. Why?
(Expected reasoning: When you
suck you increase the volume of
your lungs, which reduces the air
pressure inside your lungs and your
mouth. The atmospheric pressure
acting on the surface of the liquid is
now greater than the reduced air
pressure inside your mouth, so drink
is pushed up the straw by the
pressure excess of the atmosphere
over your mouth pressure. The
absence of atmospheric pressure on
the surface of the liquid in the
closed bottle means that there is no
excess pressure to push the liquid up
the straw).
Group 4: The syringe
Instructions
o A syringe has a
piston which
slides smoothly
inside a cylinder
m a k i n g a n
airtight seal.
o To fill a syringe,
start with the
piston at the
bottom of the
cylinder. Place
the nozzle below the liquid surface
and pull the piston upwards. This
produces a low pressure in the
cylinder below the piston. How a
syringe works?
o (Expected inference: The greater
atmospheric pressure on the
surface of the liquid pushes it up the
nozzle into the cylinder. When the
syringe is removed from the liquid,
as air is unable to get back into the
cylinder below the piston, the
atmospheric pressure at the
opening of the nozzle helps to keep
the liquid inside).
o When the syringe is used the piston
is pushed down the cylinder
applying increase pressure to the
liquid and forcing it out of the nozzle
against the atmospheric pressure.
Activity 2
Instructs the students to follow the
following steps to make a homemade
barometer capable of measuring
changes in air pressure.
Teachers’ Guide Lesson Plans: Physics

49
Step 1
Cut a large part of balloon and stretches
it tightly over the jar opening .Use a
rubber band to hold at fast
Step 2
Pinch one straw end flat and cut a point
with scissors at this end

Step 3
Glue the straw other end to the centre of
the stretched balloon
Step 4
Fasten a file card to the wall place the
barometer by it. Have the straw pointer
centered on the card and almost touching
Make a mark on the card, where the
straw points each day.
Explain the working of the barometer in
the following day
Increased air pressure pushes down
harder on the balloon diaphragm.
This makes the straw pointer go up.
Decreased air pressure caused the
higher air pressure inside the jar to
push up on the diaphragm so the
pointer goes down.
Only thing that can affect the proper
working of this barometer are the rapid
temperature changes. Place this kind of
barometer at the place, where it will
have the least changes of temperature
otherwise the air in the jar may expand
and contract so much that the effects of
changing air pressure will be obscured.
Ask the following questions to students
to complete their observations:
a. On what day was the air pressure
highest?
b. On what day was the air pressure
Teachers’ Guide Lesson Plans: Physics

50
lowest?
c. When, if at all, were there no
changes in the air pressure?
Asks the students to note the air
pressure by this barometer everyday
they come to school sharp at 8:00
o'clock for six consecutive days and
plot a graph showing changes in air
pressure.
Activity 3
Explain the working of the mercury
barometer with the help of a chart.
Ask the students what do you see in the
picture (Mercury Barometer)
Share the following information about
the height of liquid column used to
measure the atmospheric pressure.
Encourage students to ask you any
questions that they might have
What Is a Barometer?
A barometer is a widely used weather
instrument that measures atmospheric
pressure (also known as air pressure or
barometric pressure) - the weight of the air
in the atmosphere. There are two main
types of barometers – the most widely
available and reliable Mercury Barometers,
or the newer digital friendly Aneroid
Barometer.
How does a Barometer Work?
The classic mercury barometer is
typically a glass tube about 3 feet high
with one end open and the other end
sealed. The tube is filled with mercury.
This glass tube sits upside down in a
container, called the reservoir, which
also contains mercury. The mercury
level in the glass tube falls, creating a
vacuum at the top.
The barometer works by balancing the
weight of mercury in the glass tube
against the atmospheric pressure just
like a set of scales. If the weight of
mercury is less than the atmospheric
pressure, the mercury level in the glass
tube rises. If the weight of mercury is
more than the atmospheric pressure,
the mercury level falls.
Atmospheric pressure is basically the
weight of air in the atmosphere above
the reservoir, so the level of mercury
continues to change until the weight of
mercury in the glass tube is exactly
equal to the weight of air above the
reservoir.
In areas of low pressure, air is rising
away from the surface of the earth more
quickly than it can be replaced by air
flowing in from surrounding areas. This
reduces the weight of air above the
reservoir so the mercury level drops to a
lower level.
In contrast, in areas of high pressure, air
is sinking toward the surface of the
earth more quickly than it can flow out
Teachers’ Guide Lesson Plans: Physics

51
to surrounding areas. There is more air
above the reservoir, so the weight of air
is higher and the mercury rises to a
higher level to balance things out
Some barometers have a tube containing
a column of mercury that moves with
changing pressure. The higher the
pressure, the farther the mercury rises in
the tube.
Pressure = (density of mercury) x
(acceleration due to gravity) x (height of
the mercury column)
= 13590x9.81x0.760 Pascal
= 101300 Pascal
So the standard atmospheric pressure is
760 mm of Hg and 1 atmosphere
pressure is equal to 101300 Pascal.
Standard Atmospheric Pressure
Call on a volunteer to do the following
calculations on the black board to
calculate the standard atmospheric
pressure.
A pressure of 760 mm of Hg is known as
standard atmospheric pressure or 1
atm. Its value in Pascal can be calculated
as by estimating the pressure at the
bottom of the mercury column 760 mm
high
The density of the mercury is 13590
kg/cubic meter
Acceleration due to gravity is 9.81
Newton/ kg
The height of the mercury column is 0.
760 meters
Then
Activity 4
Shows the following picture of the weather
map to the students and ask how the
weather is estimated? (Expected responses
from the students)
Weather map usually represents the
information about atmospheric
pressure at sea level
Weather changes as the pressure
changes, with low pressure signaling
bad weather and high pressure brining a
settled, fine weather.
Heavy rains and strong winds are
brought by low atmospheric pressure.
Conclusion/Sum up
We live at the bottom of a deep ocean of air
called the atmosphere. It may be look not very
dense, but it exerts a very high pressure.
In some ways, the atmosphere is like a liquid.
Teachers’ Guide Lesson Plans: Physics

52
it pressure acts in all direction and become
less as we rise up through it .Unlike a liquid
however the atmosphere pressure is very
high at the lower Levels since the
atmosphere is much dense at lower levels.
Down at in sea level, the air pressure is about
100,000 Pascal (100,000N/m2) equivalents to
the weight of 10 cars pressing on each square
meter.
We are not crushed by the atmospheric
pressure, since the pressure in our blood
system is more than enough to balance it. Our
ears are very sensitive to changes in pressure
when we travel up a hill quickly in a car, the
outside air pressure drops as we rise up
through the atmosphere and we experience a
popping sensation in our ears.
Some useful application of a pressure
difference.
Assessment
Explain:
Why it is difficult to remove the lid from a
preserving jar which was closed when the
space above the food was full of steam.
Why evaporated milk flows out of a can more
easily if two holes are made at opposite sides
of the can top.
Why dams which hold water in reservoirs
must be much thicker at the base of the dam
than at the top.
Why high-flying aircraft need to be airtight
and have pressurized cabins for the people.
Change in atmospheric pressure in a region
may indicate a change in the weather.
Teachers’ Guide Lesson Plans: Physics

53
Follow-up
Prepare flash cards showing, “How atmospheric pressure manifests itself in everyday life physical
phenomenon of nature?” Discuss these cards in class room seminar.
Use a homemade barometer to estimate the atmospheric pressure for one month and compare its
reading with the standard weather report on the air pressure in your area.
Explain how squeezing and releasing the bulb of the drooping pipette will fill that pipette.
Teachers’ Guide Lesson Plans: Physics
dropping
pipette
Investigate how a fire extinguisher works.

54
Information for Teachers
Electric Power & Joule's Law 141414
UNIT
T O P I C
Current Electricity
Lesson Plan
10
Grade X
Describe how energy is dissipated in a
resistance and explain Joule's law.
2
Apply the equation E = IVt = I Rt = t
to solve numerical problems
Calculate the cost of energy when given the
cost per KWh.
Students’ Learning Outcomes
R
2
V
Duration/Number of Period
40 mins/1 period
Electrical energy is converted into the internal
energy of a conductor which results in the rise
of temperature.
If the heat produced is sufficiently high, the
wire may glow and give off light.
In the filament bulbs, the rise in temperature
is so large that they start emitting light.
The P.d is the energy or work done per unit
charge in displacing it from one point to the
other.
Teachers’ Guide Lesson Plans: Physics

55
Cost =
1000
P(in watts) x t(in hr)
x No. of days x cost of one unit
Material/Resources Required
Bulb, battery, connecting wire, bulb holder,
textbook X etc.
Introduction
The current is the rate of flow charge i.e.,
According to Ohm's law.
V = IR - (iii)
Using value of Q & V in eq (i)
2
Energy transfered = w = It x IR = I Rt
The conclusion was reached by Joule & Lenz
working independently and is known as Joul's
law.
The electrical energy is measured with joule
meter (electric meter)
The commercial unit of electrical energy is
KWh.
KWh is the energy supplied/consumed for
one hour at the rate of 1000 watts.
In practical application the units of power
used are kilowatt (KW) Megawatt (MW) and
horse power (hP).
1 KW = 1000 w
6
1 MW = 10 w
1 hP = 746w
Power is the rate at which electrical energy is
transferred (from place to place) or
transformed (from one form to another).
or
Energy transferred (J) = Power (W) x Time (s)
To find the cost of energy, it is more
convenient to calculate the total energy in
kwh.
Cost = number of kilowatt-hours x price per
kilowatts hours.
The voltage of an electrical appliance is
usually the same as that of domestic main
supply.
In Pakistan the voltage of electrical supply is
220V.
The cost of electrical consumption is given as
P.d = V =
Q
W
 W = QV - (i)
I = Q/t Q = It - (ii)
Power (W)=
time (s)
Energy transferred (J)
Activity
Construct a circuit in class room by using
connected wire, cell and blub.
Ask students to observe it.
conventional
current
battery
filament
conducting
wire
bulb
Ask the following questions to recall from
the students:
Q1: What energy changes take place
when we switch on the bulb?
Ans: Electrical energy is converted into
the internal energy of the Filament
of the bulb which results in the rise
of temperature. In case of the
filament of the bulbs, the rise in
temperature is so large that they
start emitting light.
Q2: What energy changes take place
when we switch on the heater?
Ans: When the electricity is passed
through the element of the heater
Teachers’ Guide Lesson Plans: Physics

56
Activity 1
With the help of students perform the
following calculations on the black board
and explain to the students.
What is the potential difference?
The potential difference (P.d) between two
points in a circuit is the work done per unit
charge in displacing it from one point to the
other.
What is electric current?
The current is the rate of flow of the
electrical charge i.e.,
I = Q/t Q = It - (ii)
Development
(NICROME WIRE) , the electrical
energy is changed into the heat
energy .
Q3: What relation we can use to
calculate the power dissipated?
Ans: Power is equal to the square of the
voltage divided by resistance.
Q4: What is the relation between power
dissipated and the resistance of the
heating element?
Ans: The lower is the resistance of the
heating element, the greater is the
power dissipated
Q5: What is the unit for the
measurement of the power?
Ans: Power is measured in joules per
second or watts.
Q6: What are the other units for the
measurement of power?
Ans: Larger powers are measured in Kw:
1Kw=1000 watts
P.d = V =
Q
W
 W = QV - (i)

What is Ohm's Law?
According to Ohm's law - The current
flowing through a metal conductor is
directly proportional to the potential
difference across its ends provided the
temperature and the other physical
conditions remain the constant.
Mathematically we can write
V = IR - (iii)
What is Joule's law for the energy
dissipation in resistors?
Using value of Q & V in eq (i)
2
Energy dissipated = w = It x IR = I Rt
The conclusion was reached by Joule & Lenz
working independently and is known as
Joule's law.
What is power in an electrical circuit?
When current flows through a resistor, all
the potential energy lost by the charges is
changed into heat. In many circuits it is
important to know the rate at which such
energy changes take place.
When energy changes from one form to
another, the power indicates the rate at
which the change is taking place.
Power=energy transferred/time
If energy is measured in joules (J) and time
in seconds (s), then power is measured in
joules/second or Watts
Units for the measurement of power in an
electrical circuit
In practical application the units of power
used are kilowatt (kw) megawatt (Mw) and
horse power (hP)
3
1 kw = 1000 w = 10 w
6
1 Mw = 10 w
1 hP = 746w
Formula for the calculation of the cost of
electrical consumption
The cost of electrical consumption is
given as
Teachers’ Guide Lesson Plans: Physics

57
Activity 2
Teacher asks the students to carry out an extensive survey of electrical appliances at their
homes. In their survey they collect the information and complete the given table.
If cost of one electrical energy unit = Rs.5
Cost = Power (in watts) x time (in hours) x No. of days x cost of one unit (kWh)
1000
Bulb
Fan
T.V
Total
Cost of
Energy
Average
Monthly
Electric Bill
Energy
Consumed
Estimated
Usage
(hour per day)
Power
Rating
No. of
Appliances
Appliances
Activity 3
Hang the following information sheet in the class
on the board and ask the following question to the
students:
Q1: What is the standard voltage supply in
Pakistan?
Ans: 220 volts
Q2: What is the standard voltage at which all
the electrical appliances work properly?
Ans: 220 volts
Q3: Which appliance use, the highest electrical
energy?
Ans: Electric Oven
Q4: Which appliances should be used at the
minimum to reduce monthly bill?
Ans: Electric oven, Electric heater, geyser and
electric kettle
Appliances
Power
Rating of
Appliances
(in w)

Voltage
Rating of
Appliances
in Volt
Bulb
Tube Light
Electric Fan
T.V
Electric Iron
Room Heater
Geyser
Electric Kettle
Electric Oven

15 – 200
40
60 – 100

120
750
1000
1500
2000
3000
220

220

220
220
220
220
220
220
220
Teachers’ Guide Lesson Plans: Physics

58
Activity 4
Give following word problems to
students to solve.
Help them where needed.
(1)In a certain house, 4 electric bulbs of
100W each, and daily used for 5 hours. If
the rate of electricity is Rs. 4 per unit,
find the number of units consumed in
30 days and what would be its cost?
Solution:
Step 1: The number of units consumed =
watt x time of use (in hours)/1000
= 4 x 30 days x 5h x 100w/1000 60kWh
= 60units
Step 2: Total Cost = number of units
consumed x cost of one unit
= 60 x 4 = Rs. 240/-
(2) A student uses two 150w lamps for 6
hours. If the price per unit of electricity
is Rs. 10 what is the cost of this?
Step 1: Calculate the power being used, in
kW:
Power=2 x 150 W = 300 W = 0.3 kW
Step 2: Calculate the energy transferred, in
kWh:
Energy transferred = power x time
= 0.3kW x 6h = 1.8kWh
Step 3: Calculate the cost:
Cost = number of kilowatt-hors x
price per unit
=1.8kWh x 10 = 18 Rs.
Conclusion/Sum up
Electric
current
Chemical
Effect i.e
electroplating
Magnetic
Effect i.e
Door bell
which consumes
power and energy
given by
can cause electric
shocks or fires in
situations such as
P = IV
where
P = power (W)
I = current (A)
V = potential
difference (V)
E = Pt
where
E = energy (J)
P = power (W)
t = time (s)
Damaged
insulation
Overheating of
cables
Damp conditions
which can be
prevented by
using
used in finding
the cost of
electricity
consumption in
Safety
measures
Kilowatt-hours
(kWh) or
residential units
of electricity
Effects of Current
Heating
Effect
Light energy
Heat energy
Teachers’ Guide Lesson Plans: Physics

59
Assessment
Q1: A manufacturer uses substandard wires in
the windings of the electric motors. This
reduces its cost. Is it advisable?
Ans: No, the cost of the electrical energy
consumed would be increased
Q1: How does the heating effect depend upon
current?
Ans: Amount of heat energy increases on
passing more current
Q1: How many 60 w lamps operated at 220V
can be switched on at the same time if
there is a 5A fuse in the lighting circuit?
Ans: No. of Bulb s x power of one bulb = V x I
n x P = VI
n x 60 = 220 x 5
n =
= 18.6
No. of bulbs should not exceed 18 otherwise fuse
will blow.
Q1: Enlist energy changes which can be
observed as electric current is passed through
each of the following appliances?

60
220 x 5
Appliances Energy Changes
(a) Electric Heater
(b) Electric Lamps
( c) Electric irons
Electrical energy is
converted to heat energy.
Electrical energy is
converted to heat and
light energy.
Electrical energy is
converted to heat energy.
Appliances Energy Changes
(a) Electric Heater
(b) Electric Lamps
( c) Electric irons
Expected Answers
Follow-up
Ask the students to design a poster indicating
therein strategies to minimize energy
consumption after discussing as a whole group,
share ideas and problems.
Q: Make recommendations to reduce your
electric consumption.
Ans: Actions that can reduce the electricity bill:
Turn off all the unnecessary lights. Develop a
habit to turn off the bulbs every time you go
out of the room.
Use laptop instead of the desktop computer
Minimize the use of the air conditioners,
electric iron electric heater, washing machine
etc.
Try to dry out your clothes in the sun light
instead of using dryer of the washing
machine.
Do not operate the electrical appliances on
stand by , just turn them off.
Try to make maximum use of sun light in
homes and offices.
Operate air-conditioner at 26 degrees.
 Try to use quality controlled certified cables
in your wiring systems.
Use energy savers instead of ordinary bulbs.
Raise the interior temperature of your freezer
and refrigerator.
Solar garden lights should be used in place of
those connected to the home's electrical
outlets.
Table lamps should be used instead of ceiling
lights when reading a book.
Teachers’ Guide Lesson Plans: Physics

The students will:
Distinguish between D.C. and A.C.
State the functions of live, neutral and
earth wires in the domestic main supply.
Describe hazards of electricity (damage
insulation, overheating of cables, damp
conditions)
Explain the use of safety measures in
household electricity (fuse, circuit breaker,
earth wire).
Students’ Learning Outcomes
60
Information for Teachers
The current which is steady and does not vary
with time is called direct current (DC).
Cells and batteries supply D.C.
Alternating Current (A.C),
Safety Measures
141414
UNIT
T O P I C
Current Electricity
Lesson Plan
11
Grade X
Teachers’ Guide Lesson Plans: Physics

61
The current which continuously changes in
strength and reverses its direction many
times in a second is called A.C.
A fuse is a safety device/wire and is the
weakest point in an electrical circuit.
Fuse melts and breaks the electric circuit
when the circuit gets overheated with large
withdrawal of current due to short circuiting
or due to power fluctuation.
A fuse has low melting point. Fuse made from
o
50% of tin and 50% of lead melts at 200 C.
Fuse has high resistivity.
Thicker is the fuse wire, more is the current
needed to melt it. These are normally rated at
1A, 2A, 3A, 5A, 10A and 13A. Its rating is
slightly more than the current flowing
through the appliances.
The color of the wires used in an electrical
circuit are:
Live – Brown
Neutral – Blue
Earth – Green/yellow
Earth wire is a low resistance wire connected
to the metal casing of the appliances. It
protects from electric shock.
Large amount of current produces greater
amount of heat which may damage the
conducting wire. This is called overheating.
When live wire gets contacted with the
neutral wire the circuit is called short circuit.
Human body can withstand only a current of
50mA. The resistance of the body is very low
hence large electric current cause an electric
shock and even death.
While changing the fuse, switch off the mains.
Duration/Number of Periods
40 mins/1 period
Material/Resources Required
Connecting wires, bulbs, switch, fuses and
batteries
Introduction
Activity
Asks and discuss the following questions
from the students
Activity 1
Show the two pin plugs and three pin plugs
to the students and explains the functions
of live wire, neutral wire and the earth wire
to the students
Development
No. Questions Answers
1
How the light is produced in the
electrical lamp ?
How the heat energy is produced
in the electric heater?
2
Due to
current
Electricity
change into
heat energy
Teachers’ Guide Lesson Plans: Physics

62
Informs the students that Power plugs have
to be wired according to the international
color code.
The blue wire is the neutral conductor
and it conducts electricity from the
appliance to the power source.
The brown wire is the live conductor
and conducts electricity from the power
source to the appliance.
The yellow-and-green wire is the earth
wire and it conducts excess electricity
away when there is a short circuit.
Activity 2
Ask the students to use the appropriate
color to indicate how they would wire the
power plug in the following sketch:
Asks the students to investigate do some
research on Internet or consult some lab
manual to find out “why it is important to
have an earth wire while operating a
kettle?”
The earth wire is a safety wire which
connects the metal body of the kettle to the
earth and prevents it from becoming live if a
fault develops. If for example, the live wire
to work loose and touch the body of the
kettle, a current would immediately flow to
the earth and blow the fuse. If there were
no earth wire, the body of the kettle would
remain live and a possible lethal current
would flow through the anyone who
happened to touch it
Activity 3
Show the following symbol to the students
and asks them the following questions:
Have you ever seen this sign? (Yes, No)
What does it mean? (Danger)
Why is it exhibited at electricity plants? ( To
make them inform)
Activity 4
Tell the students to go the library and search
out the safety measure for safe working
with electricity and then prepare a chart
and hang it in the class room
Electricity is dangerous. Remember the
following safety measures when you work
with electricity:
Never try to repair a broken electrical
appliance yourself. Rather ask a trained
electrician to do the job.
Water is a good conductor of electricity.
Never work with electricity when you are
near water.
Do not pull a power plug from the socket
by the cord.
Ensure that you know where the
building's main switch is so that you will
be able to switch off the main stream
immediately if something should go
wrong.
Do not install electrical cords underneath
carpets. It is too difficult to check the
condition of the cord if it is not visible at
all times.
It is good policy to get a qualified
electrician to check electrical appliances
from time to time
Teachers’ Guide Lesson Plans: Physics

63
Activity 5
By showing the pictures of fuse and circuit
breaker and also ask the following question
Q1. What is fuse?
Ans. A fuse interrupts
excessive current
(blows) so that
further damage by
overheating or fire
i s p r e v e n t e d .
Fuses are selected
to allow passage of normal current
plus a marginal percentage and to
allow excessive current only for
short periods.
Q2. How the fuse is placed in the circuit?
Ans. Like the switch, it is placed in the live
wire often in the form of small
cartridge inside the plug
Q3. How the fuse works?
Ans. If too high current flows in the
circuit, the fuse blows and breaks
the circuit before the cable can
overheat and catch fire
Q4. What is a circuit breaker?
ans:. A circuit breaker is
an automatically
operated electrical
switch designed to
protect an electrical
circuit from damage
caused by overload or short circuit.
Q5. How the fuse is different from the
circuit breaker?
Ans. Unlike a fuse, which operates once
and then has to be replaced, a circuit
breaker can be reset (either
manually or automatically) to
resume normal operation
Conclusion/Sum up
There are three wires in the electrical supply
to a house. The blue wire is the neutral
conductor and it conducts electricity from the
appliance to the power source.
The brown wire is the live conductor and
conducts electricity from the power source to
the appliance.
The yellow-and-green wire is the earth wire
and it conducts excess electricity away when
there is a short circuit
Fuse and circuit breaker protect fixed
insulation cables from overheating and
possible fire risk.
Earth wire protects the user from electric
shocks. Damped condition may be fatal for
human beings.
Assessment
Ask the following questing to assess the students
learning.
Explain why, for safety, you should disconnect
the battery before working on a car engine.
Explain why do should not:
Fly kites near overhead cables?
Connect to many appliances to one socket?
Leave a television set plugged in overnight?
Follow-up
1. Class quiz on electricity related hazards
topics.
2. Ask the students to make three posters on
Teachers’ Guide Lesson Plans: Physics

64
common electrical hazards and display the posters on main notice board of the school.
Teachers’ Guide Lesson Plans: Physics
3. Find out why:
bathroom lights have to be switched on and off by a pull-cord;
extension leads shouldn’t be coiled up tightly when in use;
electric drills and food mixers are double insulated.
Switch off all heating appliances if
the power fails.

Fires have been
caused when power returns
unexpectedly.

Wear dry leather gloves when
welding. Touching the electrode can
be dangerous because of the
voltage present.

Switch off before pulling out

a plug.
Grasp the plug –

not the cord.

Tie the tapes of the electric blanket
to prevent creasing.

Don’t spray household cleaners and
insecticides on power points or
switches. They may cause cracking
and an electrical hazard.

Teach children that power points
and appliances are not toys.
Children can touch live pins of
plugs. Plastic covers for power
points reduce the chance of children
inserting objects.

Combustible material must be kept
clear of all heating appliances, such
as

bedding, clothes, curtains,
furniture, newspapers, etc.

Some ov erseas products may not
operate satisfactorily or safely
because

of

at

240V,

50Hz supply.
Such

products could not

be

used
without modification. Have them
checked before use.

Sample Poster for Teachers

Students’ Learning Outcomes
65
Information for Teachers
1. Magnetic Fields are not the only source of a
Magnet. Tests with iron fillings and a plotting
compass show that a wire has a magnetic field
around it whenever a current is passed
Force on a current carrying
conductor in a magnetic field
151515
UNIT
T O P I C
Electromagnetism
Lesson Plan
12
Grade X
The students will:
Explain by describing an experiment that
an electric current in a current carrying
conductor produces a magnetic field
around it
Conduct an experiment to identify the
pattern of magnetic field of a (1)permanent
magnet (2) straight Current carrying
conductor (3) circular coil carrying current
using iron fillings and a magnetic compass
Describe the application of the magnetic
effect of an electric current in relay, door
latch, loud speaker and a circuit breaker
Teachers’ Guide Lesson Plans: Physics

66
Duration/Number of Periods
120 mins/3 period
Material/Resources Required
Compass needle, metallic conductor in the form
of strip or wire, battery, power supply, Iron stand,
switch
through it
Right hand rule is used to find out the
direction of the magnetic field produced
around a straight current carrying
conductor .This rule states, “If the thumb
of the right hand points in the direction of
the conventional current in the wire then
fingers encircle the wire in the direction of
the magnetic field lies”
2. If the current is passing through a loop of wire
or a coil, then again the magnetic field is
developed, outside the coil, the field lines run
in the loops from one face of the coil to the
other. The field is similar to that produced by a
short bar magnet and the coil acts as if it has a
north pole on one face and a south pole on
the other. Right hand grip rule is used to find
out which of the two faces is the North Pole.
3. When the current is passed through the
solenoid, each turn acts as a single coil and
produces a magnetic field. All the turns in a
combined way give rise o a magnetic field that
is similar to the field around a long bar magnet
and the coil behaves as if it has a north pole at
one end and a south pole at the other. The
poles of the magnet thus produced can be
determined by the Right Hand Grip Rule that
states, “Imagine your right hand is gripping
the coil in such a way that your fingers are
curled in the direction of the conventional
current flow, then the extended thumb points
in the direction of North Pole”
4. Electromagnets are widely used as
components of other electrical devices, such
as motors, generators, relays, loudspeakers, hard
disks, MRI machines, scientific instruments,
and industrial lifting electromagnets for
picking up and moving heavy iron objects like
scrap iron. The discovery of electro-
magnetism has played a vital role in
developing the present day technology
oriented society.
Introduction
Activity 1
Provide the bar magnets, iron fillings and
compass needles to the students in groups
and ask them to draw the magnetic field of
the permanent bar magnet by passing
following instructions (students already
know to draw magnetic field of the bar
magnet using compass needle)
Fix a sheet of paper on a drawing board
Place a bar magnet on the sheet of
paper
Trace the boundary NS of the bar
magnet
Place a compass at the North Pole
The magnetic needle comes to rest in a
particular direction
Mark the ends of the needle. The tail
end of the needle is the south pole and
the tip of the needle is the north pole
Now move the magnetic needle in such
a way that its tail (south pole) always
points towards the north pole of the bar
magnet
Mark the new position of its north pole
Repeat this until you reach the other
end of the magnet
Join the points
Teachers’ Guide Lesson Plans: Physics

67
These points form a curve
The curved line represents a magnetic field line or magnetic line of force
Repeat the above procedure and draw as many lines as you can
Activity 2
Asks the students to set up the electric circuit
according to the following circuit diagram using
connecting wires, battery cells, plotting
compass, variable resistance switch etc
Ask the students to pass an electric current through the circuit by closing the switch and
make the following observations.
Sr. No Activity performance Expected Observation Expected Inference
1
Place
a
plotting
compass
above

the

wire

XY

at

position

A

and

note

what

happens?

It
would
deflect
and
settle
to
a
point

to

the

east

as

in

the

position

A

Presence
of
magnetic
field

2
Place

a

plotting

compass

below

the

wire

as

in

position B?
It

would

point

in

the

west

direction

Presence

of

magnetic

field

in

the

reverse

direction
Activity 1
Ask the students to use connecting wires, copper wire AB, a piece of card board, compass
needle, ammeter, rheostat, iron fillings, battery and a switch to set up a simple circuit to
observe the magnetic field around a straight current carrying wire.
Ask the students to perform the activity step by step as is mentioned in the procedure and to
note down the observations and draw the corresponding inferences after group discussion.
Development
Teachers’ Guide Lesson Plans: Physics

68
No.

Activity

performance

Expected Observation

Expected Inference

Arrange

a

copper

wire

AB,

ammeter,

compass

needle,

battery

and

a

thick

sheet

of

cardboard

with

a

hole

at

its

centre

as

shown

above–keep

the

switch

open

in

this

case

Circuit

is

set

up

as

per

circuit

diagram

Circuit

is

an

open

circuit

1.

Sprinkle

some

iron
filings

on

the

cardboard

and

Gently

tap

the

cardboard

The

iron

filings

do

not

show

any

change

in

their

arrangement

because

no

current

is

flowing

through

the

conductor

In

the

absence

of

any

current

in

the

circuit,

the

iron

fillings

do

no

rearrange

themselves

in

some

specific

pattern

2.

Now

switch

on

the

current

in

the

circuit

and

gently

tap

the

iron

fillings

The

iron

fillings

rearrange

themselves

in

concentric

circles

with

copper

wire

at

the

centre

The

rearrangement

of

iron

filling

in

concentric

circles

shows

the

presence

of

magnetic

field

around

the

wire

3.
Increase

the

magnitude

of

current

in

the

circuit

using

a

rheostat

The

iron

fillings’

response

to

rearrange

them

in

concentric

circles

is

more

pronounced

than

in

the

previous

case

The

strength

of

the

magnetic

field

produced

due

to

flow

of

current

in

the

wire

AB

is

directly

proportional

to

electric

current

4.
Switch

on

the

current

in

the

circuit

and

tap

the

card

board

sheet.

Use

the

plotting compass to find
out the direction of the
magnetic field
The

concentric

circles

are

representing

the

magnetic

field

and

the

magnetic field direction is
clockwise–the current in
the copper wire AB is
from top to the bottom
When

the

current

is

flowing

from

top

to

the

bottom

of

the

copper

wire

AB then the direction of
magnetic field is clock wise
5.
Teachers’ Guide Lesson Plans: Physics

69
6.

Reverse

the

direction

of

the

current

in

the

circuit

and

Use

the

plotting

compass

to

find

out

the

direction

of

the

magnetic

field

By

reversing

the

current

in

the

circuit

,

the

magnetic

field

direction

comes

out

to

be

anti

clockwise–the

current

in

the

copper

wire

is

now

from bottom to the top
When

the

current

is

flowing

from

the

bottom

to

the

top

of

the

copper

wire

AB

then

the

direction

of

the

magnetic

field

is

anti

clockwise

7.
Now imagine that you are
holding the current
carrying conductor in your
right hand in such a way
that thumbs points in the
direction of the current,
then note down the
direction in which the
fingers

of

your

hand

are

curled

The current is flowing
from bottom to the top
of the copper wire
Thumb is pointing in the
direction of the current
The fingers are curled in
the direction of magnetic
field that is in the anti
clock

wise

direction

If we hold the current
carrying conductor in our
right hand in such a way
that thumb points in the
direction of the current
then the direction in which
the fingers are curled is
the direction of magnetic
field

produced

-

Famous

right

hand

rule

for

determination

of

the

direction

of

magnetic

field

around

a

straight

current

carrying

conductor

Activity 2
Divide the class into groups to perform the laboratory work.
Give instructions to the students to set up apparatus as shown in the circuit diagram given
below to investigate the magnetic field produced due to flow of the electric current in the
circular loop of wire.
Ask the students to take a long wire and bend it to form a circle.
Ask them to pass the wire through the cardboard such that half the wire is above it and the
remaining part of the wire is below the cardboard.
Instruct them to join the free ends of the wire to the battery through a plug key.
Ask them to perform the experiment step by step as shown in the table below and to record
their observations to draw inferences.
Teachers’ Guide Lesson Plans: Physics

70
No.

Activity performance

Observation

Inference

1.

Set

up

the

circuit

as

shown

in

the

circuit

diagram
Circuit

is

set

up

as

per

circuit

diagram

Circuit

is

an

open

circuit

2.

Sprinkle some
iron filings on
the cardboard
and

Gently

tap

the

cardboard
The iron filings do not show any
change in their arrangement
because no current is flowing
through

coil

In the absence of any
current in the circuit the
iron fillings do no rearrange
themselves

in

some

specific

pattern

3.

Now

switch

on

the

current

in

the

circuit

and

gently

tap

the

iron

fillings



Circular

pattern

is

around

the

points

where

the

wire

passes

through

the

cardboard



The

pattern

near

the

centre

of

the

loop

is

almost

straight.



The

concentric

circles

become

larger

as

we

move

away

from

the

wire



The

rearrangement

of
iron

filling

in

concentric

circles

shows

the

presence

of
magnetic

field

4.
Use

a

plotting

compass

to

trace

the

magnetic

field

The

field

is

traced

and

direction

of

the

current

flow
in

the

loop

of

wire

is

noted.
It
is
noticed
that
magnetic
field at centre of the loop is
perpendicular to the plane
containing the loop
5.

What result you can
infer while carefully
observing

the

pattern

of

magnetic

lines

of

force

 Concentric circles are formed,
which are centered at the
points

where

the

wire

passes

through

the

cardboard



The

lines

near

the

centre

of

the

loop

are

almost

straight.

The

magnetic

field

at

the

centre

of

the

loop

is

perpendicular

to

the

plane

of

the

loop


The

concentric

circles

become
larger

as

we

move

away

from
the wire
One face of the loop is
behaving as south pole and
other

is

behaving

as

north

pole

6.
Increase the
magnitude of current
in the circuit using a
rheostat
The iron fillings’ response to
rearrange them in concentric
circles is more pronounced than in
the previous case. The number of
the concentric circles increases
with
increase
in
the
current
The strength of the
magnetic field produced
due to flow of current in the
loop is directly proportional
to electric current strength
Teachers’ Guide Lesson Plans: Physics

71
7.

Now

reverse

the

direction

of

the

current

in

the

circuit

and

use

the

plotting

compass

to

find

out

the

direction

of

the

new

magnetic

field

lies

The

magnetic

field

reverses

its

direction
The

direction

of

the

magnetic

field

is

reversed

when

this

direction

of

flow

of

the

current

in

the

circuit
is

changed.

8.

Now

imagine

that

you
are
holding
the
current carrying loop
of wire in your right
hand in such a way
that the fingers are
curled in the
direction

of

the

flow

of

the

current

in

the

loop

then

find

out

the

nature

of

the

pole

on

the

face

of

the

loop

in

the

direction

in

which

the

thumb

points

out

by

using

a

compass
needle

or

by
bringing

a

freely
suspended

bar
magnet

close

to

the
loop
When

the

fingers

are

curled

in

the

direction
of
flow
of
the
current
in
the wire ,then thumb points out in
the direction of the north pole of
the short disk magnet that
produces the same magnetic field
as that of loop of wire at its centre
when

a

current

is

passed

through

it

When

the

fingers

of

the

right
hand
are
curled
in
the
direction of the flow of the
current in the circular loop
of wire , then thumb points
in the direction of the north
pole of the magnet that
produces

the

same

magnetic

field

as

that

of

the
circular

loop

of

wire

at

its

centre

due

to

flow

of

the

current

–

famous

right

hand

grip

rule

The

loop

of

wire

acts

as

if

it
has

a

north

pole

on

one

face

and

a

south

pole

on
the

other.

Activity 3
Show the following picture to the students
and ask them to describe, “How the
magnetic field of a coil is identical to the
field of a disk shaped permanent magnet”
Activity 4
Ask the following questions from the
students
What is the function of an electrical switch
in a circuit?
(It is used to make electricity to flow in the
circuit and to stop it to flow in a circuit when
desired)
What is the use of loud speakers in everyday
life?
(Loud speakers are used to magnify the
sound effects)
Teachers’ Guide Lesson Plans: Physics

72
Where the loud speakers are mostly used?
(Loud speakers are mostly used in mosques,
with computers and in radios etc)
What is the function of a circuit breaker?
(Under predetermined designed
conditions, it stops the flow of electric
current in the circuit)
What is main purpose of putting locks on
doors?
(To provide security to the assets)
After getting responses from the students
provide the circuit diagrams of the following
instruments that operate by making use of
electromagnet and explain their mode of
working.
Electric relay
Loud speaker
Magnetic circuit breaker
 Magnetic door latch
Circuit diagram #1
the circuit therefore no magnetic
attraction exists over the small metal
“coin” ( we call armature ), the relay
contact on the left is still open , no
current flows through the yellow
battery
When the blue battery is connected,
current flows through the coil and a
magnetic field is produced in, the iron
core/nucleus placed along the axis of
the coil. The magnetic field produced
attracts the armature and it is pulled
against the nucleus, closing the relay
contacts at the left. This action
completes the electric circuit and the
yellow battery current flows through
the lamp, lightening it.
When the blue battery current is
interrupted , coil stops to generate the
magnetic field , the armature becomes
free the and the spring effect of the
contact arm pushes it up , opening the
contact , turning off the yellow battery
current and the lamp
Circuit diagram # 2

A relay is a switch which is operated by
the electromagnet.
When the blue battery is disconnected
from the electric coil, no current flows in
Electric Relay
Loud speaker
Teachers’ Guide Lesson Plans: Physics

73
A loud speaker has a permanent magnet
and a electromagnet.
To make sound waves in the air, the
paper cone must be made to vibrate
back and forth
The current flowing in the coil is the
alternating current supplied by the
amplifier. , it flows back and forth in the
wire of the electromagnet coil. Its
oscillations are the electric version of
the sound waves that the listener wants
to hear.
The current flows one way around the
coil, turning it into a magnet .One end is
the north p[ole and the other end is the
south pole . When the current changes
direction. the poles reverse
The permanent magnet has unchanging
poles. , north at one end and south at
the other end. When the current flows
one way through the coil, it is attracted
by the permanent magnet, when the
current reverses, it is repelled.
This means the coil is pushed back and
forth. It is attached to the paper cone ,
so the cone also moves back and forth
The cone pushes the air, sending
oscillations to the listener's ears. these
oscillations are sound waves
Circuit diagram # 3
Magnetic circuit breaker
This uses an electromagnet. If the current exceeds the rating of the circuit-
breaker the pulling force of the electro-
magnet attracts an iron latch which
breaks the electrical contacts.
The 'springy piece of metal' acts as a
catch to reset the switch. The force of
attraction between the iron rocker and
the electromagnet has to be large
enough to overcome the spring catch.
Once the iron rocker has been moved
down on the left hand side of the pivot
the side on the right is pushed past the
catch
Circuit diagram # 4
1. Magnetic latches /magnetic locks use
electromagnetism to control the locking
mechanism. They rely on electricity,
either through the construction of the
current or the battery.
2. The core of a magnetic locking system is
a solenoid in advanced metal alloys. When electricity activates, the bolt
Teachers’ Guide Lesson Plans: Physics

74
Conclusion/Sum up
A magnetic field always exists around a
straight current carrying conductor in the
form of concentric circles with conductor at
the centre.
The magnetic field lasts as long as the current
is passing through the wire.
The direction of the magnetic field around the
straight current carrying conductor is
reversed if the direction of flow of the current
in the circuit is reversed.
The direction of the magnetic field around the
slides in and out, up or down along its U-
shaped channel to lock or unlock the
door.
3. Some magnetic locks also include
synchronization mechanisms that allow
them to operate only at certain times –
during working hours, for example.
Others have “transaction memory”
which records each use or attempted
use.
4. This can be particularly useful with locks
that use the number pad instead coded
cards: if an unauthorized person tries to
access using incorrect codes more than
twice, for example, the automatic
locking triggers an alarm.
straight current
carrying conductor
is determined by
the right hand rule
that states, “If the
thumb of the right
hand points in the
direction of the conventional current in the
wire then fingers encircle the wire in the
direction of the magnetic field.
The magnetic field pattern produced by a
current flowing in a circular loop of wire
shows that outside the coil, the field lines run
in the loops from one face of the coil to the
other. The field is similar to that produced by a
short bar magnet and the coil acts as if it has a
north pole on one face and a south pole on
the other
Right hand grip rule for determination of the
direction of magnetic field produced by flow
of current in a circular loop of wire or a coil.
This rule states that, “Imagine your right hand
is gripping the coil/ circular loop of wire in
such a way that your fingers are curled in the
direction of the conventional current flow,
then the extended thumb points in the
direction of North Pole”
Assessment
Ask the following questions from the students
1. What is the relation between the existence of
the magnetic field around a current carrying
wire and the flow of electric current in the
circuit? (Expected answer: When a current is
Teachers’ Guide Lesson Plans: Physics

75
flowing through a current carrying conductor
then a magnetic field exists around it. This
magnetic field lasts as long as long as the
current is flowing in the circuit).
2. What is the effect on the direction of the
magnetic field when the direction of the
current in the wire is reversed? (Expected
answer: The direction of the magnetic field is
also reversed).
3. What is the shape of the magnetic field
around a straight current carrying conductor?
(Expected answer: The magnetic field around
a straight current carrying conductor is in the
form of concentric circles with conductor at
the centre).
4. What is the name of the rule that is used to
find out the direction of the magnetic field
around straight current carrying conductor?
(Expected answer: Right hand rule for
determination of the direction of magnetic
field around a straight current carrying
conductor)
5. When the current is passed through a circular
loop of wire then what is the effect of the two
faces of the loop? (Expected answer: The
magnetic field pattern produced by a current
flowing in a circular loop of wire shows that
outside the coil, the field lines run in the loops
from one face of the coil to the other. The field
is similar to that produced by a short bar
magnet and the coil acts as if it has a north
pole on one face and a south pole on the
other).
6. What is the effect on the direction of the
magnetic field when the direction of the
current in the circular loop of wire is
reversed? (Expected answer: The direction of
the magnetic field is also reversed).
7. When the current is passed through the coil of
wire then where the strong magnetic field is
produced? (Expected answer: When the
current is passed through the coil of wire then
the strong magnetic field is produced along its
axis that makes its one face south pole and the
other face a north pole)
8. What is the name of the rule that is used to
find out the direction of the magnetic field
produced by the flow of current in a circular
loop of wire or coil? (Expected answer: Right
hand grip rule for determination of the
direction of magnetic field produced by flow
of current in a circular loop of wire or a coil)
9. Name some electrical instruments from your
daily life that operate on the principles of
electromagnetism.(Expected Answer : loud
speaker , door bell , door latch , electric relay ,
magnetic circuit breaker etc)
Follow-up
Project;
Make a poster through a library search or web
search on the issue, “Role of electromagnets
in developing a technology based modern
world”
Teachers’ Guide Lesson Plans: Physics

Students will be able to:
describe that a force acts on a current
carrying conductor placed in a magnetic
field as long as the conductor is not parallel
to the magnetic field.
Students’ Learning Outcomes
76
Information for Teachers
1. When a current is passed through a
conductor, a magnetic field is produced
Turning effect on a current
carrying coil in a magnetic field
151515
UNIT
T O P I C
Electromagnetism
Lesson Plan
13
Grade X
around it. When a current carrying conductor
is placed in a magnetic field of a permanent
magnet, a force F is produced. This force acts
on the current carrying conductor and is at
right angles to both the current direction I in
the conductor and direction of magnetic field
B.
2. The direction of the force can be found by the
Flemings' Left Hand Rule that states, “If the
thumb and the first two fingers of the left
hand are held at right angles to one another,
the thumb gives the direction of the thrust
(force) if the first finger points in the same
Direction
of Force
Magnetic
Field
Direction
of Current
Teachers’ Guide Lesson Plans: Physics

77
direction as the field B and the second finger
points in the same direction as the current I”
3. Magnitude of the force F on a current carrying
conductor depends upon the strength of the
magnetic field B, the magnitude of the
current I, length L of the conductor and the
orientation of the conductor in the magnetic
field.
Duration/Number of Period
120 mins/3 period
Material/Resources Required
U shaped strong permanent magnet, bar
magnets, Connecting wires, Battery cells,
Compass needle, Power supply, Iron stand,
Computer with internet connections to show PPt
presentations and demonstrations.
Introduction
Activity
Ask the students to set up the
apparatus using metallic
conductor AB, battery,
connecting wires, switch etc
according to the circuit
diagram. Then the current is
switched on in the circuit and
the students are instructed to
perform the following activities
and make the observations to
draw inferences.
1.
Set up the circuit as shown in the
circuit diagram
Circuit is set up as per
circuit diagram

Circuit is an open circuit
2.

Close the switch .Place a plotting
compass under the

conductor AB
The

plotting compass
shows a displacement

There is magnetic field
produced due to the flow
of current in the circui t in
the conductor
3.
Now switch off the current in the
circuit and again place a plotting
compass under the conductor AB

The plotting compass
does not show any
displacement
There is no magnetic field
when there is no current
in the circuit
No. Activity performance Observations Inferences
Teachers’ Guide Lesson Plans: Physics

78
Activity 1
Divide the students in groups to
perform the experiment.
Tell the students to use the same
experimental arrangement as in
activity # 1 of the introduction
and ask the students to perform
the experiment step by step as
instructed by him /her and
record the observations on their
observation sheet.
 Allow them to discuss the
observations among themselves
and guide them in drawing
inferences from the observations.
Experimental arrangement to observe
the force on a straight current carrying
conductor placed in a magnetic field.
Development
A: Orientation of the conductor - at
right angles to the magnetic field direction
1.

Now switch on the current in
the circuit and bring a U
shaped magnet closer to the
conductor in such a way that:



its poles do not touch the
conductor
 These poles have conductor
in between them in such a
way such that it makes an
angle of 90 degrees with
the magnetic lines

of

force
of the permanent magnet (
The length of the conductor
AB is at right angles to the
magnetic field produced by
the magnet )

As soon as the U
shaped magnet is
brought closer to the
conductor as per
instruction and
precaution , there is a
sudden displacement of
the conductor

The displacement of the
current carrying conductor
when placed in the
magnetic field of a
permanent magnet shows
that there is a force acting
on the conductor
N

S

A

B

Teachers’ Guide Lesson Plans: Physics
No. Activity performance Observations Inferences

79
2.

Reverse the direction of
current in the circuit and
bring a U shaped magnet
closer to the conductor in
such a way that :



its poles do

not touch the
conductor



These poles have conductor
in between them in such a
way such that it

makes an
angle of 90 degrees with
the magnetic lines of force
of the permanent magnet (
The length of the conductor
AB is at right angles to the
magnetic field produced by
the magnet )

As soon as the U
shaped magnet is
brought closer to the
conductor as per
instruction and
precaution , there is a
sudden displacement of
the conductor but in
the opposite direction
to that as observed in
step 4

The direction of force acting
on the conductor is
reversed when direction of
flow of current is reversed
in the conductor and

the
conductor is placed in a
magnetic field of
permanent magnet in such
a way that it makes an
angle of 90 degrees with
the magnetic field direction
3. Reverse the poles of the U
shaped magnet and bring it
closer to the conductor in
such a way that :


its poles do

not touch the
conductor



These poles have conductor
in between them in such a
way such that it makes an
angle of 90 degrees with
the magnetic lines of force
of the permanent magnet (
The length of the conductor
AB is at right angles to the
magnetic field produced by
the magnet )

As soon as the U
shaped magnet is
brought closer to the
conductor as per
instruction and
precaution , there is a
sudden displacement of
the conductor but in
the opposite direction
to that as observed in
step 5

The direction of force acting
on the conductor is
reversed when the
direction of applied
magnetic field is changed
by reversing the poles of
the magnet

or by reversing
the direction of the
magnetic field

N

S

A

B
S

N

A

B

B:Orientation of the conductor -

parallel to the

magnetic field direction

4.

Now reverse the poles
magnets and bring the U
shaped magnet closer to the
conductor in such a way that



its poles do

not touch the
conductor
 These poles have
conductor in between
them in a way that
conductor is parallel to the
As soon as the U
shaped magnet is
brought closer to the
conductor as per
instruction and
precaution , there is no
displacement of the
conductor observed
When the conductor is
placed parallel to the
magnetic field

lines of

force
of

a permanent magnet ,
then no force acts on the
conductor
Teachers’ Guide Lesson Plans: Physics

80
magnetic lines of force of
the permanent magnet (
The length of the
conductor AB is parallel to
the magnetic field
produced by the magnet )

N

S
A B
b
5.

Invert the poles of the U
shaped magnetic field and
bring it closer to the
conductor in such a way that
 its poles do not touch the
conductor


These poles have conductor
in between them in a way
that conductor is parallel to
the magnetic lines of force

of the permanent magnet (
The length of the conductor
AB is parallel to the
magnetic field produced by
the magnet )

As soon as the U
shaped magnet is
brought closer to the
conductor as per
instruction and
precaution , There is no
displacement observed

When the conductor is
placed parallel to the
magnetic lines of force , it
does not experience any
force in any orientation
6.

Reverse the direction of the
current in the conductor.
Bring the U shaped
permanent magnet and bring
it closer to the conductor in
such a way

that



its poles do

not touch the
conductor



These poles have conductor
in between them in a way
that conductor is parallel to
the magnetic lines of force
of the permanent magnet (
The length of the conductor
AB is parallel to the
magnetic field produced by
the magnet )
As soon as the U
shaped magnet is
brought closer to the
conductor as per
instruction and
precaution , There is no
displacement observed

When the conductor is
placed parallel to the
magnetic lines of force, it
does not experience any
force .Direction of flow of
the current in the
conductor and direction of
the magnetic field does not
affect this behavior. So we
can infer that

Whenever

the

straight current carrying conductor
is placed parallel to the
magnetic field –

no force
acts on it

S

N
A B

A B

N

S

C:Dependence of force on magnetic field strength

B

, length L of the conductor and current I
in the conductor

7.

Now

use three permanent U
Shaped magnets of increasing
strengths and repeat the step
5

of the activity

The conductor is
deflected in a more
stronger way or to

a
greater extent when
the permanent magnets
of greater strengths

are
used
The

force acting on the
conductor that produces
displacement in the
conductor is directly
proportional to the
magnetic field strength Bof
the permanent magnet
Teachers’ Guide Lesson Plans: Physics

81
8.

Increase the magnitude of
current in the circuit and
repeat step 5 of the activity

The intensity of
displacement again
increases

The force F

acting on the
conductor that produces
displacement in the
conductor is directly
proportional to the
magnitude of the current I

flowing in the circuit

9.

Repeat the step 5

of the
activity using conductors of
different lengths



When we
increase the length of
the conductor the
intensity of the
displacement is
increased

 When we
decrease the length of
the conductor , the
intensity of the
displacement is
decreased
The force F

acting on the
conductor is proportional to
the length L of the
conductor

10. From the teachers’ Lab
manual/ text book

, find out
the statement of the
Fleming’s

Left hand rule
which describes the direction
of the force acting on the
current carrying conductor
placed in a magnetic field of a
permanent magnet

Flemings left hand rule
states, “If the thumb
and the first two fingers
of the left hand are
held at right angles to
one another, the thumb
gives the direction of
the thrust (force) if the
first finger points in the
same direction as the
field B

and the second
finger points in the
same direction as the
current I”
The Flemings left hand rule
can be used to find the
direction of the force on a
current carrying conductor
placed in a magnetic field of
a permanent magnet

11.

Now come to the step 5 of
the activity and apply the
Fleming’s left hand rule to
find the direction of the force
F that acts on the conductor
AB of length L carrying
current I When it is placed at
right angles to the field
direction of a permanent
magnet.

When we extend our
left hand in such a way
that first finger extend
in the direction of
magnetic field B and
second finger points in
the direction of the
current flowing in the
conductor then force F
of the conductor is
along the Thumb .
The direction in which the
force acts on a current
carrying conductor is at
right angles to both the
magnetic field of a
permanent magnet and the
current flowing in the
conductor.

So

Teachers’ Guide Lesson Plans: Physics

82

Direction
of Force
MagneticField
Direction
of Current
Activity 2
Demonstrate the following activity for the students to strengthen their concept. Proceed with the
following statement :
Let us find out the logical explanation for the force acting on a current carrying conductor when
placed in the magnetic field of a permanent magnet at right angles to the magnetic field
direction
Step #1
Ask the students to use two pictures given below one showing the magnetic field of a permanent
bar magnet on a paper and the other showing the magnetic field of a straight current carrying
conductor carrying current towards the reader and out of the paper .The second picture is on the
transparent sheet used in the over head projector.
Pictures that can be used by the students
Teachers’ Guide Lesson Plans: Physics

83
x
A circle with a DOT shows that
the current is coming OUT
form the plane
A circle with a CROSS shows that
the current is moving IN TO
the plane
Field Pattern Of Straight Wire
No.

Questions

Expected answers

1.

What is the shape of the magnetic
field of the permanent magnet?

The magnetic lines of force are straight lines
originating from the north pole and
terminating on the south pole
2. What is the shape of the magnetic
field produced around a current
carrying conductor (0)?

The current in the conductor is flowing out
of the paper towards the observer and the
magnetic field is in the form of concentric
circles with the conductor at the centre and
is presented by (0) The direction of the
magnetic field is anticlockwise.

Step#2 :
Ask the students to put the paper on the table showing the
magnetic field of a permanent bar magnet and ask them to put
the transparent sheet having magnetic field due a straight
current conductor traced on it in such a way that the magnetic
field of the straight current carrying conductor is overlapping the
magnetic field of permanent magnet drawn on the paper in the
following way
F
N
Force
A Conductor in a Fixed Magnetic Field A Current Carrying Conductor in a Fixed Magnetic Field
Teachers’ Guide Lesson Plans: Physics

84
Step#3:
Ask the students to observe carefully and answer the following questions:
No.

QUESTIONS

EXPECTED ANSWERS

1.

In what region the two fields that is one
produced by the bar magnet and the other
produced by the current carrying conductor are
reinforcing each other?

In the left hand region the two
fields are reinforcing each other

2.

In what region the two fields that is one
produced by the bar magnet and the other
produced by the current carrying conductor are
cancelling the effect of each other?

In the right hand region

3.

Where is the region of resultant weaker magnetic field?
In the right hand region

4. Where is the region of stronger magnetic field? In the left hand region
5. What should be the result of the existence of a weaker region of magnetic field and a region of
stronger magnetic field in the same area?
There should be a resultant force
that should act on the conductor
6. What should be the direction of this force? It should be directed from the
region of stronger magnetic field to
the region of weaker magnetic field

7.

What should be the effect of this force?

The conductor should move from the region of stronger magnetic
field to the region of weaker
magnetic field.

8.

What should be the direction of this force?

It should be at right angles to both
the magnetic field direction of the
permanent magnet and the current
I flowing through the conductor.

1.

Can you predict the angles between direction of
the magnetic field B, current I in the conductor
and the resultant force F on the conductor?

Yes three quantities that are field B,
current I in the conductor and the
resultant force F are perpendicular
to each other.

2. Can you apply the Fleming’s left hand rule to confirm your answer?
We can extend the left hand in such
a way that first finger points in the
direction of magnetic field
produced by the bar magnet and
the second finger points in the
direction of flow of the

current in
the conductor then the thumb
points in the direction of the force.

Teachers’ Guide Lesson Plans: Physics

85
Conclusion/Sum up
When a current is flowing through straight current carrying conductor , then a magnetic field is
produced around it in the form of concentric circles with conductor at the centre
When the current carrying conductor is placed in the magnetic field of permanent magnet such
that it makes an angle of 90 degrees with the magnetic lines of force of the permanent magnet then
a force acts on the conductor and it is displaced.
Fleming's left hand can be used to find out direction of the displacement. The rule states that ,'If
the thumb and the first two fingers of the left hand are held at right angles to one another, the
thumb gives the direction of the thrust (force) if the first finger points in the same direction as the
field B and the second finger points in the same direction as the current I”
There are four factors that are affecting the force acting on the current carrying conductor placed
in the magnetic field of a permanent magnet. These are length L of the conductor, current I flowing
in the conductor, Magnetic field strength of the permanent magnet and the orientation of the
conductor in the magnetic field.
The direction of the force exerted on the current carrying conductor is at right angles to both the
direction of flow of the current in the conductor and magnetic field direction
Assessment
NO. QUESTIONS EXPECTED ANSWERS

When a straight current carrying
conductor is placed in a magnetic
field of a permanent magnet then
what happens?
It experiences a force and it gets
displaced
 If we reverse the direction of fl ow of
the current in the conductor then
what happens?
It reverses the direction of the
displacement of the conductor
 If we reverse the magnetic field
direction of the permanent magnet
by inverting it poles, then what
happens?
The direction of displacement is again
reversed
 How we can increase the force acting
on a current carrying conductor
when placed in the magnetic field of
a permanent magnet for its fixed
orientation?
We can increase this force by increasing
length or by increasing magnetic field
strength of the permanent magnet or
by increasing the current in the circuit
Teachers’ Guide Lesson Plans: Physics

86

 For what orientation in the magnetic
field, the conductor experiences the
maximum force?
When the current carrying conductor is
placed at right angles to the direction of
the magnetic field , then it experiences
the maximum force
 For what orientation i n the magnetic
field, the conductor experiences the
minimum force?
When the current carrying conductor is
placed parallel to the direction of the
magnetic field. , then it experiences no
force
 Which rule is used to find out the
direction of the force be ing exerted
on a current carrying conductor
placed in the magnetic field of a
permanent magnet
Fleming’s left hand rule
 What is the statement of the
Fleming’s left hand rule?
If the thumb and the first two fingers of
the left hand are held at right angles to
one another, the thumb gives the
direction of the thrust (force) if the first
finger points in the same direction as
the field B and the second finger points
in the same direction as the current I”

 Can you give a pictorial presentation
of Fleming’s left hand rule?

Follow-up
PICTURE DESCRIPTION Ask the students to describe the pictures in their own words as shown
below in detail
Magnetic Forces Acting on Parallel Current Carrying Conductors
Two parallel conductors carrying current in the same direction will attract each other
Teachers’ Guide Lesson Plans: Physics

87
Magnetic Forces Acting on Parallel Current Carrying Conductors
Two parallel conductors
carrying currents in opposite
directions will repel each
other, and they will set up
a polarized magnetic field
between themselves,.
Excursion
The students can visit an electrical instruments workshop and observe the different electrical
instruments using electromagnets as their key components. They are then asked to prepare short
report on what did they observe there.
Teachers’ Guide Lesson Plans: Physics

Differentiate between analogue &
digital electronics.
State the basic operations of digital
electronics.
Identify and draw the symbols for the
logic gates (OR, AND, NOT, NOR, NAND).
State and verify the action of logic gates
in truth table form.
Demonstrate the simple uses of logic
gates.
Students’ Learning Outcomes
88
Information for Teachers
Electronics circuit can be classified as digital or
analogue.
The number of states or voltages level is
limited in a digital circuit, usually to two.
An analogue circuit has an infinite number of
voltage levels.
T here are several kind of logic gates AND, OR,
NAND, NOR.
NOT gate functions as an inverter i.e. the
output is always the opposite of the input.
Analogue and digital
electronic/logic gates
161616
UNIT
T O P I C
Introductory Electronics
Lesson Plan
14
Grade X
Teachers’ Guide Lesson Plans: Physics

89
For the AND operation, the electronics circuit
gives a HIGH output (1) only if all its inputs are
HIGH.
An OR gate is coincidence detector for LOW
and conditions.
NAND and NOR gates are the inverter of AND
and OR gates respectively.
Duration/Number of Periods
160 mins/4 period
Material/Resources Required
syringe, pressure gauge, connecting tube,
analogue and digital watch,
Introduction
Digital Electronics has had a great impact on our
society. It has given rise to calculators, digital
watches, cell phone, micro computers and many
other gadgets of daily uses.
Many our homes and buildings have electronic
control systems for cooling, heating and security.
It is important to know the ways in which a small
number of electronic components can be
arranged to different ways to produce various
kinds of control circuits. Most modern electronic
systems are digital.
Activity 1
Take a 50 mL syringe and connect it to a
pressure gauge, as shown in Figure 1. Press
the piston, the gauge shows pressure. More
pressing of piston will show more pressure.
The pressure on gauge can have any value
from zero to a maximum value, depending
on the push on the piston.
This is an example of analogue system.
Figure 1
Syringe
Pressure
Gauge
Activity 2
Connect a switch S with a battery and a lamp
(Figure 2). When the switch is open, the
lamp is off. When the switch is closed, the
lamp turns on. This systems has only two
possible states.
 Switch open: Lamp off
 Switch closed: Lamp on
Two state system is an example of a digital
system. Some other digital quantities are.
One of the
States
The other
State
1 2 3 4
High
Low
1
0
On
Off
Yes
No
X=1
S
Figure 2
Example of analogue and digital
systems and their wave form
Analogue
Watch
t
V
Analogue Signal
Figure 3
Teachers’ Guide Lesson Plans: Physics

90
t
V
Digital Watch Digital Signal
Figure 4
Advantages of Digital Systems: Digital
systems can only have certain definite
values usually just on or off and hence are
less affected by noise or distortions from
other sources. A digital system is less
affected by noise or distortions from other
sources.
Binary Code:
Two states things are called Boolean
variables represented by 0 and 1 known as
binary numbers.
Discussion points:
 What is a code?
 What code system can you name?
 What are the advantages and
disadvantages of a code system?
 What are binary numbers?
The on-off principle of the electric circuit is
useful means of illustrating the binary
numbers used in computer language.
Binary means “two”. Numbers in binary are
made up of only two digits 1 and 0. Each
digit is a bit, which is short for “binary
digits”. Computers process digital signals
that are in the form of electric pulses. Each
pulse stands for 1. Each missing pulse stands
for zero.
LINKS- MATHEMATICS:
Explain base number system (e.g. 2 as the
0 1 2 3
base of computer codes i.e. 2 , 2 , 2 , 2 .....).
Switch:Switch is basic building block of all logic
circuits. It is the combination of switches
which provides us many different functions
that digital electronics circuits can perform.
Truth Label:
A truth table is a good way to show the
functions of a logic gate. It shows the output
states of every possible combination of
input states.
The inverting circle:
Some gates symbols have a circle on the
output which means that their function
includes inverting of the output.
BASIC OPERATIONS AND LOGIC GATES:
All information is converted into binary
numbers using Boolean algebra based upon
three basic operations
1. OR operation A*B
2. AND operation A+B
3. NOT operation A
Logic Gates are the electronic circuit which
in fact are combinations of electronic
switches. They implement the various logic
(Boolean) operations. They have two or
more inputs except a NOT gate which has
only one input. All gates have only one
output. The letters A, B, C, are used to label
inputs and 'x' is used to label output. Digital
electronics are representations of Boolean
Algebra, used in computers, cell phones and
a number of consumer products. Digital
circuits are usually made from large
assemblies of logic gates.
Remember that digital signals have only
two values:-
“1” and “______” or
“High Voltage” and “ ______ ________” or
“On” and “_______” or
“True” and “________”
Teachers’ Guide Lesson Plans: Physics

91
Activity 1
Construct the circuit diagram as shown in
the figure (Fig.3) with the help of switches,
wires, battery and bulb in parallel. Perform
the activity and make the truth table for all
combinations of inputs and outputs turn by
turn for the four cases. Compare the truth
table with that of an OR gate.
Development
A = 0
B = 0
X = 0
Figure 5OR Operations
A=1
B=0
X=1
A = 0
B = 1
X = 1
A = 1
B = 1
X = 1
OFF
OFF ON
ON
ON ON
OFF
OFF
Input
A
Input
B
Output
Bulb X
OR GATE:
OR gate can be regarded as two “switches”
A and B connected in parallel. If either A and
B or both switches are closed, the indicator
lamp will light. The gate gives an output igh h
(1) or when both inputs are high (1).
A
Truth Table for OR Gate
0
0
0
0 0
1
1
1 1 1
1
1
B Output
Input A
Input B
Output
Figure 6
OR Gate
Activity 2
Repeat the above activity connecting now
in series combination as shown in Fig. and 8
make the truth table for all combinations of
inputs and outputs. Compare the truth
table with that of AND gate.
Teachers’ Guide Lesson Plans: Physics

Activity 3
NOT GATE: Consider Figure 10, when switch
S is open the lamp is on. But when the
switch is closed the lamp is off due to short
circuit. This is an example of NOT gate. The
output of NOT gate is opposite to the input.
It puts as an inverter. It has only one input.
92
OFF
OFF ON
ON
ON ON
OFF
OFF
Input
A
Input
B
Output
Bulb X
A
X= 0
B
A = 1
X= 0
B = 0
A = 0
X = 0
B = 1
A = 1
X = 1
B = 1
Figure 8
AND Operations
AND GATE
AND gate can be regarded as two switches A
& B connected in series. Output is high or
one only when both inputs are high (1).
Input A
Input B
Output
Figure 9
AND Gate
A
Truth Table for AND Gate
0
0
0
0 0
1
1
1 1 1
0
0
B Output
S
Figure 10
Switch in Opposite
Teachers’ Guide Lesson Plans: Physics

93
NAND GATE
It is a NOT gate coupled with AND gate.
A
Truth Table for NOT Gate
0
1
1
0
Output
NOT Gate (Inverter)
Input
A
Figure 11
Output
A
X = A.BB
Truth Table for NAND Gate
0
0
0
0 1
1
1
1 1 0
1
1
A
Figure 12
NAND Gate
A
B
A.B
X = A.B
NOR gate
It is a NOT gate coupled with OR gate.
X = A+BB
Truth Table for NOR Gate
0
0
0
0 1
1
1
1 1 0
0
0
A
A
B
A+B
X = A+B
Figure 13
NOR Gate
Activity 4
CONTROL SYSTEMS USING LOGIC GATES
Control systems are sensing circuits that
monitor the conditions we want to
control. They produce suitable digital
signals either low or high voltages. The
basic structure is shown in Figure 1 .4
The input section senses changes in
some aspects of the environments, like
temperature, smoke or light intensity.
The output is some device that causes a
change in the environment, like heater
or a lamp. The process finds out what
change in the inputs will cause the
output to change.
APPLICATIONS OF LOGIC GATES
Logic Circuit: Burglar Alarm:
Consider a situation where by two switches
A and B are placed, one each near the
hinges of each door. When door is one
opened, the switch is opened and burglar
alarm starts sounding. So long the door
remains closed, the switches are closed and
burglar alarm remains off. The truth table
for such a system to work is.
This a truth table for NAND gate. Hence
using a NAND gate, burglar alarm can be
made.
Input(s) Process Output(s)
Figure 14
Teachers’ Guide Lesson Plans: Physics

94
Input B
Truth Table
0
1 0
0
0 1
1
1
Input X Output X’Input A
Closed
Closed
Open
Open
Closed
Open
Closed
Open
Figure 15
Logic Circuit: Burglar Alarm
A
B
X’
Connected to one Door
Connected to other Door
X
Alarm
Conclusion/Sum up
Basic logic gates are OR, AND and NOT.
OR and NOT combination makes NOR and the
combination of NOT and AND is called NAND
gate.
The function of NOT gate is an inverter. “Output
is always opposite of input.
Assessment
1. The inputs of a gate are 1 and 0. Identify
the gate if its output is (a) 0, (b) 1.
2. The output of two inputs of OR gate is 0
only when its:
i. Both inputs are zero
ii. Either input is zero
iii. Both inputs are one
iv. Either input is one
3. The output of AND gate is 1 only when its:
i. Both inputs are zero
ii. Either input is zero
iii. Both inputs are one
iv. Either input is one
4. What is the name of the operation when
single input = 0 gives an output = 1
5. When will the output of NAND gate be
zero?
6. The output of an NOT gate is connected to
input of another NOT gate.
Draw up a truth table for their
arrangement
Write a sentence to describe its effect
7. If the input at A and B are at logic 1, give
the correct output stage at 'x' for these
gates.
o AND gate
o NAND gate
o NOR gate
8 What logic gate is represented by:
OutputInput A
0
1
1
0 1
0
0
1 1 0
1
1
Input B
Teachers’ Guide Lesson Plans: Physics

95
S1
S2
Switches in Parallel
S
Switch in Opposite
The bulb will light under certain conditions:
What are they?
The bulb will turn on when switch S is
________, and turn off when switch S
is______due to short circut.
This circuit is for illustration only! If this was
a real circuit, what would happen to the
battery, when switch S is closed?
State two advantages of transmission of
digital TV signal through optical fibers.
Follow-up
 The bulb will light under certain conditions:
What are they?
 The bulb will turn on when switches
S1____________S2 or both are closed, for all
other combinations the bulb is off.
Teachers’ Guide Lesson Plans: Physics

The students will:
describe the components of information
technology.
describe function and use of fax machine,
cell phone, photo phone and computer.
identify various components of ICT.
make a list of the use of computer
technology in various fields of daily life.
Students’ Learning Outcomes
96
Information for Teachers
The method of storing information,
protecting information, processing the
information, transmitting the information,
and later retrieving information is called
Information Technology.
Components of Information Technology:-
1. Hardware:
2. Software
3. Data
4. Procedures
Components of ICT/
Communication technology
171717
UNIT
T O P I C
Information and Communication Technology
Lesson Plan
15
Grade X
Teachers’ Guide Lesson Plans: Physics

97
Duration/Number of Periods
80 mins/2 Priod
Material/Resources Required
Computer, White board, commonly used
hardware devices (printer, scanner, barcode
reader, charts etc.
Introduction
Activity
Take the students to the nearby super store
5. People
Information and Communications Technology
(ICT) covers the computer hardware; the
software programs; and the communications
that occur between more than one different
computerized devices.
ICT systems are those where the output from
the system goes directly to a human being or
into another ICT system.
Data is raw facts and figures or a set of values.
Data has no meaning. Information is data that
has been processed and put into context to
give it meaning. Hardware consists of physical
components of an ICT system e.g. Printer,
scanner, monitor, server, switches. In many
systems data is transmitted from one
computer to another.
Software consists of Computer Programs that
make the hardware do something useful. A
series of actions or operations intended to
achieve a result is called procedure. People
consist those who are involved in testing of
the system , sales, purchasing, finance,
operations, internal and external personnel
and let them observe the mode of working
over there.
Teachers’ Guide Lesson Plans: Physics
1
2 3
4
5
6

98
 Define the various pictures related to super store that may involve use of Information
Technology
Picture
#
Questions Expected answers
1. What the picture is
representing?
The picture is representing a super store
where we normally go to buy various products
of daily use.
2. What the lines shown in
picture depict?
The lines show bar code. It’s a secret number
shows different information about the product
like Manufacturer #, Product # and Check
digits etc.
3. How information from
bar code can be read?
Bar Code Reader is the device used to scan
the bar code information printed on any
product.

4. Have you seen bar code
printed on any product?
Yes on many products like cola tin pack,
packing of toothpaste and on the milk pack.
5. How bill is generated? When sales person finished scanning bar codes
from the products then eventually this
information is printed on a paper by a small
printer attached to the computer.
6. Have you noticed
employee identification
card of the salesperson?
Does it have any useful
information?
Yes, identification card of the employee also
contains bar code number.
Activity 1
Describe the components of information technology. Take the students to the computer lab
and brief them about the components of IT through a power point presentation. Let the
students interact with the computers and then allow them to perform various tasks on the
computer like exploring different softwares, windows properties, changing wallpapers and
screen saver etc. Then offer the following questionnaire and ask them to fill it. Allow them to
discuss the things with each other and provide full assistance and encourage their efforts.
Development
Teachers’ Guide Lesson Plans: Physics

99
Observation Activity Inferences

What does it mean by
hard ware?
All the devices that we can
physically touch in the computer /
IT lab called Hard ware

What do you mean by
Soft wares?
Computer Programs that make
the hardware do something
useful.

What is digital
technology? Use the
internet to explore the
definition of the Digital
technology?
Digital describes electronic
technology that generates, stores,
and processes data in terms of
two states: positive and non -
positive. Positive is expressed or
represented by the number 1 and
non-positive by the number 0.

What does it mean by
data?
Raw facts that are used by
programs

What people are doing
here?
Being an important component of
Information Technology, people
are working with hardware,
softwares, and process data to
make it useful.

Ask the following questions
Give definition of IT (“The method of storing information, protecting information, processing
the information, transmitting the information, and later retrieving information is called
Information Technology”).
List the Components of Information Technology:-
Teachers’ Guide Lesson Plans: Physics

100
(Hardware: The term hardware refers to machinery. This category includes the computer
itself, which is often referred to as the central processing unit (CPU), and all of its support
equipments. Among the support equipments are input and output devices, storage devices
and communications devices.
Software: The term software refers to computer programs and the manuals (if any) that
support them. Computer programs are machine-readable instructions that direct the
hardware parts (circuitry) of the system to function in ways that produce useful information
from data. Programs are generally stored on some input / output medium, often a disk or
tape.
Data: Data are raw facts that are used by programs to produce useful information.
Procedures: Procedures are the policies that control the operation of a computer system.
People: Every system needs people if it is to be useful).
Activity 2
Describe function and use of fax machine, cell phone, photo phone and computer.
Prepare a charts containing pictures of Fax Machine, Cell Phone, Photo Phone and Computer
Show the chart to the students to make them understand how the mentioned devices work
Define purpose and advantages of each device
Tell the students that fax machine transfers data through telephone lines. It takes input in the
form of paper or directly from the computer and produce output in printed form on paper
and directly shows output in computer as a soft copy.
Tell the students that cell phones based on radio technology and it is a major source of
communication.
Define the computer in understandable words that computer is an electronic machine which
after analyzing and arranging the given information, presents it in a very time. It uses various
hardware devices e.g. keyboard and mouse for input, printer and monitor for output purpose
and
Also give some examples to explain the usage of computer e.g. in shopping malls, banks,
ticket reservation centers etc.
Give advantages of computer use by telling them about fax machine, cell phone, photo
phone and computer etc.
Fax Machine Cell Phone Photo Phone Computer
Teachers’ Guide Lesson Plans: Physics

101
Ask the students to mention benefit of the device given below.
Device

Benefits

1.
__________________________________
2.
__________________________________
3.
__________________________________

1.
__________________________________
2.
__________________________________
3.
__________________________________

1.
__________________________________
2.
__________________________________
3.
__________________________________
Activity 3
Components of ICT
Make the students vigilant to and tell them that today we are going to discuss very important
topic Information and Communication Technology (ICT)
Give a brief definition of ICT as “Information and Communications Technology (ICT) covers
the computer hardware; the software programs; and the communications that occur
between more than one different computerized devices”
Define various components of ICT and quote most relevant daily life examples to make the
students understand.
Identify various
Activity 4
Assess the risks and benefits to society and the environment of introducing ICT (e.g. effects on
personal privacy, criminal activities, health and transfer of information).
After clearing the concepts of students about ICT its time to discuss benefits of ICT.
Teachers’ Guide Lesson Plans: Physics

102
How ICT is playing its positive role in our lives and how it made many tasks easier for us, let the
students forward their comments on it.
After the comments of students discus the following topics to let the students know how and
in which fields they can get benefit from ICT. E.g.
General benefits of ICT
Benefits for teachers
Benefits for students
Benefits for parents
Assign various topics to the groups of students and ask them to get information how we can
get benefit from these.
Design an activity to see how much students know about various field where computer
technology is used. Ask the students to connect the computer technology field with the
relevant example
How it is working in our livesComputer Technology Field
Online shopping stores, marketing
Online job portals
Discoveries regarding solar system
ATMs
Mobile phone technology,
video conferencing, e-mail servers
Communication
Missile control technology
Banking
Career Counseling
Science and Research
Defense
E-commerce
Conclusion/Sum up
Information Technology is use of science to
enable
The flow
The storage, and
The handling of large amounts of
information
Teachers’ Guide Lesson Plans: Physics
Assessment
1. What are the six components of an ICT
system? (expected answer: Data,
information, procedure, hard ware, software,
people.
2. Define Hardware? (expected answer: Physical
components of an ICT system e.g. Printer,
scanner, monitor, server, switches.

103
Teachers’ Guide Lesson Plans: Physics
Follow-up
Ask the students to browse the internet to investigate the Role of ICT in bridging the children of the
world around for peace building efforts
Find out how IT has helped physically disable people such as the deaf and dumb to communicate
with the world.
Draw a flow chart showing the procedure involved in purchasing a football from departmental
store each student can prepare flow chart for the activity of his own interest.

Students’ Learning Outcomes
104
Information for Teachers
Some materials naturally emit ionizing
radiation which can be penetrating and highly
dangerous. Such materials are said to be
radioactive and their radiation can be of three
types.
o Alpha radiation
o Beta radiation
o Gamma radiation
The phenomenon of spontaneous emission of
radiation from some elements like radium
and uranium is called natural radioactivity.
The radiation emitted by the radioactive
Natural Radioactivity181818
UNIT
T O P I C
Radioactivity
Lesson Plan
16
Grade X
Students will:
describe that the three types of the
radiation are alpha ( ), beta ( ) and  
gamma( )rays 
state for radioactive emissions:
1. their nature
2. their relative ionizing effects
3. their relative penetrating abilities
explain that an element may change into
another element when radioactivity occurs
represent changes in the composition of
the nucleus by symbolic equations when
alpha or beta particles are emitted
Alpha
Beta
Gamma
Teachers’ Guide Lesson Plans: Physics

105
Duration/Number of Period
40 mins/1 period
Material/Resources Required
board, chalk/marker, pictures and textbook etc.
Introduction
substances consists of three types. Alpha rays,
beta rays and gamma rays.
The direction of deflection of alpha rays in the
magnetic field indicates that these are
positively charged particles.
The direction of deflection of beta particles in
the magnetic field indicates that these are
negatively charged particles.
The direction of deflection of Gamma ray
Photons in the magnetic field show that these
radiations consist of photons only.
Activity 1
Draw the following diagrams on the black
board and explain it to the students.
Students copy these pictures on their note
books.
Neutral atoms
Negative ion
Positive ion
Ions are nothing more than atoms or
molecules that have gained or lost an
electron.
Those that have lost an electron are
called positive ions, while those that
have gained an electron are negative
ions.
Ions are formed when an electron is
detached from a neutral molecule (or
atom).
The molecule losing an electron
becomes a positive ion and the
molecule gaining an electron becomes a
Teachers’ Guide Lesson Plans: Physics

106
negative ion.
If the electrons are detached from
molecules in a gas, ions are produced
and gas is said to be ionized
The molecules with electrons missing
are the positive ions
Detached electrons join to other
molecules to form negative ions.
As ions in a gas are free to move so an
ionized gas can conduct.
Now tell the students when atoms change
into positive and negative ions is called
ionization.
Activity 2
Explain the concept of radioactivity by
consulting periodic table with students.
Development
Guide the students about the nature of Alpha,
beta and gamma radiation.
Briefs the students about the radioactive
elements in the following way and writes
important points on the board.
Henry Becquerel discovered in 1896 that
certain elements whose atomic numbers are
greater than 83 (z>83) are unstable.
These elements disintegrate to emit three
kinds of radiation called alpha, beta and
gamma radiation such elements are called
radioactive elements.
The process of emitting radiation is called
radio activity. The radioactive elements are
Radium (Z=88), Uranium (Z=92) and Polonium
(Z=84). Since it is a natural phenomenon
therefore the process is called natural radio
activity and the elements are called natural
radioactive elements.
Activity 1
Draw the following picture on the board.
Photographic plate
Lead
block
SourceNow enlist the elements having atomic
number greater than 82.
(83 84 85 86)
Bi Po At Rn
etc.
Teachers’ Guide Lesson Plans: Physics

107
Alpha particle = helium nucleus
(+2 electric charge)
Gamma ray = ultra-high-energy
non-visible light
(no electric charge)
Beta particle = electron
( - 1 electric charge)
Magnet
Radium sample Lead block



Then explain the picture to the students and then asks the following questions from students:
1. Where the radioactive source is placed? (Expected answer: The radioactive source is placed in
the lead chamber).
2. What is the mode of emission of the radiation from source and while travelling inside of the
chamber? (Expected answer: The radiation shoots out from the radioactive source and move in
a straight line before entering in the vacuum chamber).
3. What has been applied in the vacuum chamber? (Expected answer: Magnetic field is applied in
the vacuum chamber perpendicular to beam of radiation entering in the chamber and is
directed into the paper).
4. What happens in the ionization chamber? (Expected answer: The radiation splits up into three
parts)
5. What important result you can draw by the beam of radiation deflected towards left?
(Expected answer: If we use the Flemings left hand rule to the situation when the wire is
carrying current at right angles to the direction of the magnetic field (into the paper) then a
force is exerted on the current carrying conductor at right angles to both B and I The direction of
the deflection shows that the beam that is deflected towards left consists of particles having
positive charge.
6. What is the name of the radiation deflected towards left? (Expected answer: The radiation that
deflects towards left consists of particles bearing positive charge and this type of radiation is
called alpha rays).
7. What is the name of radiation that is deflected towards right? (Expected answer: The radiation
Teachers’ Guide Lesson Plans: Physics

108
that deflects towards right consists of particles bearing negative charge and this type of
radiation is called beta rays).
8. What is the name of radiation that passes without suffering any deflection in the vacuum
chamber and forms a spot on photographic plate? (Expected answer: The radiation that is
neither deflected towards right nor towards left but travels in a straight line under the applied
magnetic field in the vacuum chamber is called Gamma Ray radiation).
Explain that nature of the natural radio activity can be studied by applying the electric field even in
the following way:
Lead block Aligning slot
Radioactive source
Electric field
Detecting screen
Alpha particles
(positive charge)
gamma rays
(no charge)
Beta particles
(negative charge)



Alpha particles move toward the negative plate.
Beta particles move toward the positive plate.
Gamma rays are not deflected
Activity 2
Draw the following diagram on board and tell students about the concept of penetrating power of
radioactive rays.
Lead block Paper Wood Lead
Radioactive source
Some
gamma
rays
  
(Comparison of penetration powers of the alpha, beta and gamma rays)
Teachers’ Guide Lesson Plans: Physics

109
Activity 3
Draws the following picture on the black
board and ask the students to copy it on
their note books then explain the following
figures to them.
Emission of Alpha Particles in a nuclear
decay reaction.
The radioisotope Uranium-238 emits alpha
radiation and is transformed into another
radioisotope, Thorium-234.
Alpha particle
4
2
He
238
92
U
234
90
Th
When an atom loses an alpha particle, the
atomic number of the product is lowered by
two and its mass number is lowered by four
1. What is the atomic number of Uranium?
(Expected answer: The atomic number Z
of Uranium is 92).
2. What is the mass number A of Uranium?
(Expected answer: The mass number A
of Uranium is 235).
3. What is the mass number A of
radioisotope of Uranium-238?
(Expected answer: The mass number A
of the radioisotope of Uranium is 238).
4. How many protons and neutrons would
be lost by Uranium 238 if it wants to
emit an alpha particle? (Expected
answer: It would have to get rid of a
particle having two protons and two
neutrons to emit an alpha particle)
5. When Uranium 238 emits an alpha
particle what is then change in its
atomic number? (Expected answer: Its
atomic number decreases by 2 and the
atomic number of the product becomes
90).
6. What is name of the element in the
periodic table that has an atomic
number Z=90? (Expected answer: The
name of the element having Z=90 is
Thorium 234).
7. What is the change in the mass number
A of the Uranium when it emits an alpha
particle? (Expected answer: The mass
number decreases by 4).
8. Which one is the parent element in the
above mentioned nuclear decay
reaction? (Expected answer: Uranium
238).
9. Which one is the daughter element in
the above mentioned nuclear decay
reaction? (Expected answer: Thorium
234).
Emission of beta rays
Carbon-14 emits a beta particle as it decays
and forms nitrogen-14.
The nitrogen-14 atom has the same mass
number as carbon-14, but its atomic
number has increased by 1.
It contains an additional proton and one
fewer neutron.
1. What is the atomic number of Carbon?
(Expected answer: The atomic number Z
of Carbon is 6).
2. What is the mass number A of
radioisotope of Carbon-14? (Expected
Teachers’ Guide Lesson Plans: Physics

110
answer: The mass number A of the
radioisotope of Carbon is 14).
3. What is the effect on the composition of
the Carbon -14 nucleus if beta particle is
emitted from the nucleus? (Expected
answer: When one neutron in the
Carbon-14 nucleus is converted into
proton then an electron is created and
this electron shoots out from the
nucleus as soon as it is formed. The mass
number of remains the same but there
is a change in the atomic number. The Z
for the product is one time greater that
of the nucleus under decays).
4. When Carbon -14 emits a beta particle
what is then change in its atomic
number? (Expected answer: Its atomic
number increases by 1 and it becomes
7).
5. What is name of the element in the
periodic table that has an atomic
number Z=7? (Expected answer: The
name of the element having Z=7 is
Nitrogen -14)
6. What is the change in the mass number
A of the Carbon -12 when it emits a beta
particle? (Expected answer: The mass
number remains the same).
7. Which one is the parent element in the
0
-1
e
14
7
N
14
6
C
above mentioned nuclear decay
reaction? (Expected answer: Carbon-
14).
8. Which one is the daughter element in
the above mentioned nuclear decay reaction? (Expected answer: Nitrogen -
14).
Gamma rays emission
A high-energy photon emitted by a
radioisotope is called a gamma ray. The
high-energy photons are a form of
electromagnetic radiation.
Nuclei often emit gamma rays along with
alpha or beta particles during radioactive
decay
In the first nuclear decay reaction
,Thorium -90 is converted into Radium
88 by emitting an alpha particle , what
additional emission you can notice in
the reaction equation ? (Expected
answer: When the nucleus of Thorium-
90 emits an alpha particle, then it is
changed into Radium -88 and the
nucleus Radium -88 is left in the excited
state –high energy state. in order to get
stability, it emits a high energy photon
called gamma ray).
In the second nuclear decay reaction,
Thorium -90 is converted into
Protactinium 91 by emitting a beta
particle, what additional emission you
can notice in the reaction equation?
(Expected answer: When the nucleus of
Thorium-90 emits a beta particle, then it
is changed into Protactinium -91 and
the nucleus Protactinium -91 is left in
Teachers’ Guide Lesson Plans: Physics

111
the excited state –high energy state. In
order to get stability, it emits a high
energy photon called gamma ray).
Is there any change in the atomic
number Z when there is a gamma
emission? (Expected answer: There is
no change in the number Z during a
gamma ray emission)
What is the nature of the gamma rays?
(Expected answer: Gamma rays are high
energy photons
How the gamma ray photon is different
from X-rays? (Expected answer: The
gamma ray photon is emitted from the
nucleus when the nucleus switches
from its excited state to its ground state
X-rays are emitted when the atom is in
the excited state due to shifting of the
inner most shell electrons to the outer
most shells and jumping back of
electrons to the inner most shells.
Conclusion/Sum up
Some materials naturally emit ionizing
radiation which can be penetrating and highly
dangerous. Such materials are said to be
radioactive and their radiation can be of three
types
Alpha radiation
Beta radiation
Gamma radiation
The phenomenon of spontaneous emission of
radiation from some elements like radium
and uranium is called natural radioactivity
The radiation emitted by the radioactive
substances consists of three types. Alpha rays,
beta rays and gamma rays
The direction of deflection of alpha rays in the
magnetic field indicate that these are
positively charged particles
The direction of deflection of beta particles in
the magnetic field indicate that these are
negatively charged particles
The direction of deflection of Gamma ray
Photons in the magnetic field show that these
radiations consist of photons only.
Assessment
1. An  particle contains:
a. Two neutrons
b. Two protons
c. Two neutrons and two protons.
d. Two electrons
2. Which material is best for making a box for
the safe storage of a radioactive substance?
a. aluminum
b. glass
c. graphite
d. lead
3. Which of the following has the same
properties as a beta particle?
a. a helium nucleus
b. an electron
c. a neutron
d. a proton
4. Which of the following pair of particles/ atoms
/radiation is deflected by both electric and
magnetic fields?
a. Alpha particle and gamma radiation
b. Beta particle and gamma radiation
c. Alpha particle and a hydrogen atom
d. Alpha particle and beta particle
Answer Key:
1. c 2. a
3. b 4. d
Teachers’ Guide Lesson Plans: Physics

112
Summary of the Radioactive Decay Processes
Type of the
radioactive decay
Particle Emitted Change in Mass Number
of the parent element
Change in Atomic
Number of parent
element
Alpha Decay
Beta Decay
Gamma Emission

Expected Answer:
Summary of the Radioactive Decay Processes
Type of the
radioactive decay
Particle Emitted Change in Mass Number
of the parent element
Change in Atomic
Number of parent
element
Alpha Decay Helium Nuclei Decreases by 4 Decreases by 2
Beta Decay Beta Particle No change Increases by 1
Gamma Emission Photon No Change No Change
Teachers’ Guide Lesson Plans: Physics
Which type of radiation is a form of electromagnetic radiation?
which travels fastest alpha, beta or gamma radiation?
Why are gamma rays unaffected in a magnetic field?
Follow-up
Investigate the hazardous effects of radiations on human beings who work inside the zones of
radioactivity.
Ask the students to prepare a summary of the Radioactive Decay Processes.

115
Glossary
Teachers’ Guide Lesson Plans: Physics
Alternating current

A current whose direction changes continuously

Ammeter

An instrument used to measure the current in a circuit

Analogue
electronics

Name of processing quantities of continuous increase decrease or remaining
constant

Centre of Gravity

The point of body where its weight acts

Computer

A machine which can communicate and analyze

information efficiently and
has a vast and long last memory

Diffraction

Bending of waves round an obstacle

Digital electronics

Name of processing data provided in the form of digits

Direct current

Current which always flows in one direction

Dynamics

Study of motion of bodies under action of forces

Effort

Force applied on the machine

Effort arm

The intermediate distance between fulcrum and effort

Effort Moment

Product of effort and effort arm

Electric current
The rate of flow of electric change through any cross sectional area.
Electric field That space round a charged body in which another charge experiences its
effect in the form of a force
Electric power Amount of energy obtained from electric current in unit time
Electromagnetic
field
Production of magnetic field due to passage of electric current through a
conductor
Electromagnetic
force

The phenomena in which e.m.f is produced due to relative motion of coil and
magnet

Electromagnetic waves

Such waves, which do not require material medium of their propagation

Electromotive force

The energy needed to move one coulomb

charge through the whole circuit
including the battery

Electronics

Electronics is the study and use of circuitry involving components such as
resistors, diodes, transistors, capacitors, inductors and integrated circuits.
We divide the electronics into two main branches: one is analogue and the
other is digital.

Equilibrium

A body whose acceleration is zero

Floppy

A device used for storing computer data

Force

The agent that changes or tends to change the state of a body

Friction

The force of resistance against the relative motion between two surfaces

Fulcrum The point around which lever revolves

116
Teachers’ Guide Lesson Plans: Physics
Fuse

A special wire that protects an electric circuit. If the current gets too large,
the fuse melts and

stops the current.

Galvanometer

An instrument which indicates the current in a circuit

Information
technology

Scientific method of collecting and arranging information and import them to
others

Joule

The unit of work in system international

Kilowatt hour

Quantity of that energy which is obtained from one kilowatt power in one hour

Kinematics

Study of motion of bodies without taking into consideration the mass and force

Laser disc or CD

A device used to store data with the help of digital technology

Lever

A strong bar revolving around some point is equal to 9.46x10
15
m

Load Resistance or lifted up weight
Load arm The intermediate distance between fulcrum and load
Load moment Product of load and effort arm
Mechanics The branch of Physics which deals with the study of motion of bodies is
known as Mechanics
Power Amount of energy transferred every second. The energy can be transferred from somewhere (e.g. a power station) or to somewhere (e.g. an electric kettle.) Power = energy transferred / time taken.
Pressure The effect of a force spread out over an area. Pressure = force / area.
Rolling Friction The friction produced during the motion of one body over the other with the
help of whets
Short-circuit

Unwanted branch of an electrical circuit that bypasses other parts of the
circuit and causes a large current to flow.

Significant Figures

In a measurement, the correctly known digits and the first doubtful digit

Sliding Friction

The friction between two surfaces sliding against each other

Speed

Distance covered by a body in certain time

Speed

How far something moves every second. Average speed = distance

travelled /
time taken.

Stable Equilibrium

The condition of a body in which it comes to its original condition after being
disturbed

Static Friction

The force of friction arising due to applied external force before motion

Work

Energy transferred when a job is done.

Work = force x distance moved in
direction of force.

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