short presentation 9 ideal transformers docx

another easy to edit the front page of the physics project for final submission of the investigatory project on the ideal transformers.

1. Physics Investigatory Project
Report
All India Secondary School Examination
2025-26
Submitted by
Ashwini Kumar Rout
Class: XII
Under the guidance of
DAV PUBLIC SCHOOL,
MCL Bandhabahal Area Jharsuguda

2. CONTENT
ACKNOWLEDEMENT
CERTIFICATE
INTRODUCTION
PRINCIPLE
CONSTRUCTION
THEORY
ENERGY LOSSES
RECTIFIER
WORKING OF BATTERY ELIMINATOR
LDR CIRCUIT
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3. ACKNOWLEDEMENT
I Ashwini Kumar Rout of class XII of DAV PUBLIC
SCHOOL, MCL Bandhabahal would like to express my
special thanks of gratitude to my teacher Mr. B.R.
Acharya as well as our principal Mr. P.K. Hota who gave
me the golden opportunity to do this wonderful project
on the topic “TO INVESTIGATE THE RELATION BETWEEN
THE RATIO OF INPUT AND OUTPUT VOLTAGE AND
NUMBER OF TURNINGS IN SECONDARY AND PRIMARY
COIL IN A TRANSFORMER” which also helped me I
doing a lot of research and I came to know about so
many new things I am really thankful to them.
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4. NAME: - ASHWINI KUMAR ROUT
ROL NO:-
Class: - XII
CERTIFICATE
THIS IS TO CERTIFY THAT THE PROJECT ENTTLED “TO STUDY THE
RELATION BETWEEN THE RATIO OF INPUT AND OUTPUT VOLTAGE
AND NUMBER OF TURNINGS IN PRIMARY AND SECONDARY COIL OF A
SELF MADE TRANSFORMER” HAS BEEN PREPARED BY ASHWINI
KUMAR ROUT OF CLASS XII OF DAV PUBLIC SCHOOL, MCL
BANDHABAHAL AREA UNDER THE GUIDANCE AND SUPERVISIONING
DURING THE SESSION 2025-26. HE HAS COMPLETED THE PROJECT
WITH MUCH INTREST AND SINCERITY FOR WHICH CREDIT GOES TO
HIM SOLELY.
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5. ------------------------ ------------------------- ------------------------
Internal Signature Principal Signature External Signature
PHYSICS PROJECT
REPORT
“TO STUDY THE RELATION BETWEEN THE RATIO OF INPUT AND
OUTPUT VOLTAGE AND NUMBER OF TURNINGS IN PRIMARY AND
SECONDARY COIL IN A SELF MADE TRANSFORMER”
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6. INTRODUCTION
BATTERY ELIMINATOR:-
Battery Eliminator is a device which is used to convert high
voltage DC current, a circuit arrangement is employed with
which 220V AC is converted to 12V DC.
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7. It consists of following parts:-
TRANSFORMER:-
It is a device used to convert small AC into high voltage and
low voltage AC into a high voltage AC in our project step down
is used.
RECTIFIER:-
It is a device used to convert alternating current into direct
current. It has two types:
1.Half Wave Rectifier
2.Full Wave Rectifier
In our project full wave rectifier is used which converts full
wave of AC into full wave of DC.
MUTUAL INDUCTANCE
The mutual inductance of two coils is defined as the EMF
induced due to the magnetic field in one coil opposes the
change of current and the voltage in another coil. That
means the two coils are magnetically linked together due to
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8. the change in magnetic flux. The magnetic field or flux of one
coil links with another coil. This is denoted by M.
The current flowing in one coil induces the voltage in another
coil due to the change in magnetic flux. The amount of
magnetic flux is linked with the two coils is directly
proportional to the mutual inductance and current change.
Its theory is very simple and it can be understood by using
two or more coils. It was described by an American Scientist
Joseph Henry in the 18
th
century; it is referred to as one of the
properties of the coil or conductor used in the circuit. The
property inductance is, if the current in one coil changes with
time, then the EMF will induce in another coil. Oliver
Heaviside introduced the term inductance in the year 1886.
The property of mutual inductance is the working principle of
many electrical components that run with the magnetic field.
For example, the transformer is the basic example of the
mutual inductance. The main drawback of the mutual
inductance, leakage of the inductance of one coil can
interrupt the operation of another coil utilizing
electromagnetic induction. To reduce the leakage, electrical
screening is required.
The positioning of two coils in the circuit decides the amount
of mutual inductance that links with one to the other coil.
Application of Mutual Inductance:-
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9. Transformer
Electric Motors
Generators
Other electrical devices, which work with a magnetic
field.
Used in calculation of eddy currents
Digital signal processing
How mutual inductance is related to
transformers?
Mutual induction is a fundamental principle in the
operation of transformers. A transformer consists of two
coils of wire, usually wound around a common magnetic
core. When an alternating current (AC) flows through the
primary coil, it creates a changing magnetic field around it.
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10. According to the principles of mutual induction, this
changing magnetic field induces an electromagnetic force
(EMF) or voltage in the secondary coil. The amount of
voltage induced in the secondary coil depends on the ratio
of the number of turns in the primary coil to the number of
turns in the secondary coil. The ratio is known as the turns
ratio.
In a transformer, mutual induction allows for the efficient
transfer of electrical energy from the primary coil to the
secondary coil. The voltage can be stepped up or stepped
down depending on the turns ratio, making transformers
essential for voltage regulation, power distribution, and
transmission in electrical systems. Mutual induction is the
key mechanism that enables this energy transfer between
the coils without direct electrical connection.
TRANSFORMER
The transformer is advice used for converting a low
alternating voltage to a high alternating voltage or vice-versa.
PRINCIPLE:-
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11. A Transformer based on the principle of mutual induction
according to this principle, the amount of magnetic flux
linked with a coil changing, an EMF is induced in the
neighboring coil.
STEP-DOWN TRANSFORMER:-
A step down transformer is a device which converts high
primary voltage to a low secondary voltage. In a step down
transformer, the primary winding of a coil has more turns
than the secondary winding.
CONSTRUCTION:-
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12. The transformer consists of two coils. They are insulated with
each other by insulated material and wound on a common
core. For operation at low frequency, we may have soft iron
core. The soft iron core is insulted by joining thin iron strips
coated with varnish to insulate them to reduce energy losses
by eddy currents.
The input circuit is called primary and output is called
secondary.
THEORY:-
Suppose the no. of turns in the primary coil is NP and that in
the secondary coil is NS.
The resistance of the coil is assumed to be zero. Let dq/dt be
the rate of change of flux in each turn of the primary coil. If Ep
be the EMF in the primary circuit then.
Ep = -Np (1)
We suppose that there is no loss of flux between the primary
and secondary coils. Then, the induced EMF in the secondary
coil will be
Es = -Ns (2)
From equation 1 and 2, we find:-
For step up transformer K>1
For step down transformer K<1
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13. That is for step up transformer Ns>Np, therefore Es>Ep.
For step down transformer Ns<Np, therefore Es<Ep.
EFFICIENCY: The efficiency of the transformer is given by:
ŋ= EsIs /EpIp×100%
If Ip and Is be the currents in a primary and secondary circuits.
For ideal transformer ŋ=1=100%
Therefore, EsIs=EpIp
Therefore, for set up, transformer current in the secondary is
less than in the primary (Is<Ip). And in a step down
transformer we have Is>Ip.
ENERGY LOSSES IN
TRANSFORMER
In practice, the output energy of a transformer is always less
than the input energy, because energy looses occur due to a
number of reasons as explained below:
1.LOSS OF MAGNETIC FLUX:-
The coupling between the coils is seldom perfect. So, whole
of magnetic flux produced by the primary coil is not linked up
with the secondary coil.
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14. 2.IRON LOSS:-
In actual iron cores in place of lamination, eddy’s current are
produced. The magnitude of eddy current may, however be
small. And a part of energy is lost as a heat produced in the
iron core.
3.COPPER LOSS:-
In practice the coils of the transformer possess resistance. so
a part of the energy is lost due to heat produced in the
resistance of the coil.
4.HYSTERESIS LOSS:-
The alternating current in the coil tapes the iron core though
complete cycle of magnetization. So the energy is lost due to
hysteresis.
5.MAGNETO RESTORATION :-
The alternating current in the transformer may be set its
parts in to vibrations and sound may be produced. It is called
humming. Thus, a part of energy may be lost due to
humming.
RECTIFIER
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15. It is an electronic device used to convert alternating current
to direct current.
THE P.N. JUNCTION AS FULL WAVE RECTIFIER:-
It is a device used to convert full wave of alternating current
to full wave of direct current.
PRINCIPLE:-
It is based on the principle that a crystal diode conduct only in
forward bias and then an output current flows in the circuit.
When d1 is forward bias and d2 is reverse bias and vice versa
the diode d1 and d2 send current through the load resistance
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16. in the same direction during both halves of the time period.
This cause full wave rectification of input power
CONSTRUCTION :-
The full wave rectifier consist of two p-n junction diodes
connected to secondary part of the transformer. When input
AC is applied across the primary coil (p) of a transformer. One
terminal off the secondary coil (s) of the transformer is
connected to the positive terminal of the junction diode d2. In
the secondary part of the transformer a load resistance r1 is
connected. The output is drawn across two terminals of load
resistance.
WORKING:-
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17. In case of a crystal diode as full wave rectifier the two diodes
d1 and d2 are used in such a way that during 0 to ii crystal
diode d1 becomes f.b and on output similarly during next half
cycle ii and 2 ii crystal diode d2 becomes f.b and on output
current i2 flows in the circuit in this way a crystal diode
converts full wave of alternating current into a full wave direct
current.
EFICIENCY OF FULL WAVE RECTIFIER
The efficiency of full wave rectifier may be 80%.
THE WORKING OF BATTERY
ELIMINATOR
A battery eliminator consists of mainly three working part,
transformer, rectifier, filter circuit. In our project report step
down transformer is used. This transformer converts high
voltage to low voltage alternating current. This low voltage AC
passes from rectifier which converts AC into DC. In our project
full wave rectifier two diodes d1 and d2 are used in such a
way that during o to ii crystal diode d1 becomes F.B. and an
output current I, flow in circuit. Similarly, during next half
cycle ii and 2ii crystal diode d2 becomes F.B. and output
current flows in the circuit. In this way a crystal diode converts
full wave of alternating current into a full wave on DC. The
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18. direct current which we get fluctuating dc. In order to make it
pure DC filter circuit is used. In our project capacitor is used
as a filter circuit. It is used electrolytic capacitor capacity 16v,
1000 microfarad. The output now available is four half volt DC
and it may be suitably connected with the transistor.
LDR CIRCUIT
A photo resistor or light-dependent resistor (LDR) is a light-
controlled variable resistor. The resistance of a photo resistor
decreases with increasing incident light density; in other
words, it exhibits Photoconductivity. A photo resistor can be
applied in light sensitive detector circuits, and light and dark
activated switching circuits.
These resistors use pure semiconductors like silicon or
germanium. When the light falls on the LDR, then the
electrons get excited by the incident photons and move from
the valence band to the conductions band and therefore the
number of charge carriers increases. In other words, the
conductivity goes up.
Distinction needs to be made here between the photocells
and LDRs. In a photocell, when it is excited by light (photons),
electricity is generated. Unlike photocells, LDRs do not
generate electricity but only change their conductivity.
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19. A light dependent resistor works on the principle photo
conductivity. Photo conductivity is an electro optical
phenomenon in which the material’s conductivity is increased
when light is absorbed by the material. Modern light
dependent resistors are made of the materials such as lead
sulphide, lead selenide, indium antimonide and the most
commonly cadmium sulphide (CDS) and the cadium selenide.
When the light falls that is when the photons fall on the
material, the electrons in the valence band of the
semiconductor materials are excited to the connection band.
These photons in the incident light should have energy
greater than the band gap of the semiconductor materials to
make the electrons jump from the valence band to the
conduction band. Hence when the light have enough energy
strikes on the device, more and more electrons are excited to
the conduction band which results in large number of charges
carries. The results of this process is more and more current
starts flowing through the device when the circuit is closed
and hence it is said that the resistance of the device has been
decreased. This is the most common working principle of LDR.
CONCLUSION
In conclusion, mutual induction is a fundamental concept in
electromagnetism, showcasing the ability of changing
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20. currents in one coil to induce currents in another.
Transformers leverage mutual induction for efficient voltage
transformation in power transmission. On the other hand,
rectifiers play a crucial role in converting alternating current
to direct current, ensuring smooth power supply in various
electronic devices. Together, these concept highlight the
diverse applications of electromagnetic principles in our
modern technological landscape.
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