Electricity [Mind Map]

Class - X
Chapter - 12
Mind Map

1. Important Source of Energy
Potential Difference
It is work done per unit charge in moving a
unit positive charge between two points.
= = or 1V = 1 J/C
Its SI unit is volt.
It is a scalar quantity.
Measured by voltmeter
1mV = 10 V, 1 V = 10 V
1kV = 10 V, 1 MV = 10 V
l
l
l
l
l
l
V
–3 –6
3 6
μ
W
q
Ohm's Law
The current passing through a
conductor is directly proportional to the
potential difference across its ends, such
that the physical conditions like
temperature, density etc.,
remain unchanged.
V
V Ror =
∝I
I
Electric Current
l
l
l
l
l
Rate of flow of electric charges
through a conductor.
= or 1 A = 1 C/s.
Its SI unit is ampere.
It is a scalar quantity.
Measured by ammeter
1 mA = 10 A, 1 A = 10 A
I
–3 –6
μ
q
t
Resistivity
It refers to resistance of a conductor of
unit length and cross-sectional area.
It depends on the nature of the
substance and temperature.
Its SI unit is Ohm-metre ( -m).
l
l Ω
Joule's Law of Heating
The heat produced in a conductor is directly
proportional to the (i) Square of the current ( ),
(ii) Resistance ( ) of the conductor and (iii) the
time ( ) for which the current is passed.
Its SI unit is Joule.
I
R
t
H RT=I
2
l
H R t∝ ∝ ∝I
2
Practical Applications
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Electric bulb (to produce light)
Electric fuse that protects
circuits and appliances.
Electrical heating appliances.
Electric Charge
It is a physical quantity of matter which
causes it to experience a force when placed
near other electrically charged matter.
A body is negatively charged if it gains
electrons.
A body is positively charged if it loses
electrons.
Its SI unit is coulomb.
It is a scalar quantity.
Charges are conserved and quantised.
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Electric Circuit
l
l
A closed and continuous path through
which electric current flows.
Components of electric circuit are
cell/battery, bulb, switch/key, fuse,
connecting wire, ammeter, voltmeter,
rheostat, galvanometer etc.
Electric Power
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l
l
Rate at which electric energy is dissipated
or consumed in an electric circuit.
= = =
Its SI unit is watt.
1W = 1 J/s, 1kW = 10 W
Commercial unit of electric energy is kWh.
1 kWh = 3.6 x 10 J
P V R V /RI I
2 2
3
6
Resistance
Property of a conductor due to which it opposes the flow of current through it.
lR= or 1 = 1 V/AΩ
lIts SI unit is ohm. l1 k = 10 1m = 10Ω Ω, Ω Ω
3 –3
V
I
lIt is a scalar quantity.
Factors Affecting
Resistance
Resistance in Series
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l
Length of the conductor
Area of cross-section
Nature of material
Effect of temperature
=R
ρl
A
l
l
l
Maximum effective
resistance.
Two or more resistors are
connected end to end.
Current remains constant
but voltage varies.
V V V V= + +
1 2 3
R R R R= + +
1 2 3
Resistance in Parallel
l
l
l
Minimum effective resistance.
Two or more resistors are
connected simultaneously
between two points.
Voltage remains constant but
current varies.
I I I I= + +
1 2 3
1
R
=
1
R
1
+
1
R
2
+
1
R
3
(where, is resistivity
of conductor)
ρ
V V
B A–
q
Electricity
V
I
MIND