Physics Investigatory Project - Transformer

Class 12 Physics Investigatory Project on Transformer.
Compiled from various sources including SlideShare.

1. PHYSICS INVESTIGATORY
PROJECT
TRANSFORMERS
Jishnu Rajan
Althaf Younoos
Aravind Ravi
Xll-B
2019-20

2. Kendriya Vidyalaya Kanjikode
Department ofPhysics
CERTIFICATE
This is to certify thatAravind Ravi,Althaf Younoos and
JishnuRajan,students ofclassXII-Bhavesuccessfully
completed the research on the below mentioned project
under the guidance ofMr.Sivadas(Subject Teacher)
during the year 2019-20 inpartial fulfillment of physics
practical examination conducted by AISSCE, New Delhi.
Signature of external examinerSignature of physics teacher

3. ACKNOWLEDGEMENT
Primarily I would thank God for being able to
complete this project with success. Then I would like to
thank my physics teacher Mr.Sivadas,whose valuable
guidance has been the ones that helped me patch this
project and make it full proof success his suggestions and
his instructions has served as the major contributor
towards the completion of the project.
Then I would like to thank my parents and friends
who have helped me with their valuable suggestions and
guidance has been helpful in various phases of the
completion of the project.
Last but not the least I would like to thank my
classmates who have helped me a lot.
Althaf,Aravindand Jishnu

4. INDEX
1. CERTIFICATE
2. ACKNOWLEDGEMENT
3. AIM OF PROJECT
4. INTRODUCTION
5. THEORY
6. APPARATUS REQUIRED
7. PROCEDURE
8.OBSERVATION
9. RESULT
10. CONCLUSION
11. PRECAUTIONS
12. SOURCES OF ERROR
13. BIBILIOGRAPHY

5. AIM OF THE PROJECT
To investigate the relation between the ratio of:
1.Input and output voltage.
2.Number of turnings in the secondary coil and
primarycoil of a self-made transformer.
To find the efficiency of the self-made transformer

6. Introduction
The transformer is a device used for converting a low
alternating voltage to a high alternating voltage or vice-versa.
A Transformeris based on the principle of mutual
induction according towhich,a change inmagnetic flux linked
with a coilinducesane.m.fin the neighboring coil.
In a transformer, the electrical energy transfer from one
circuit to another circuit takes place without the use of moving
parts.
A transformer which increases the A.C. voltage is called a
Step-up Transformerand onewhich decreases the A.C.
voltage is called a Step-down transformer.
Transformer is, therefore, an essential piece of apparatus
both for high and low current circuits.

7. Theory
When an alternatingvoltageis supplied to the primary
coil,it results ina changing magnetic flux, which inducesA.C.
Voltagein the secondary coil.Inan idealtransformer, whole of
the magnetic flux linked with primary is also linked with the
secondarycoil, and then the induced e.m.f. in each turn of the
secondarycoilis equal to that induced in each turn of the
primarycoil. Thus if Epand Esarethe instantaneous values of
the e.m.f.induced in the primary and the secondarycoils,Np
and Nsare the no. of turns of the primaryandsecondary coils of
the transformerrespectively,anddф / dt = rate of change of flux
in each turn ofthe coil, then we have
Ep=-Npdф/dt _______________ (1)
Es=-Nsdф/dt _______________ (2)
The above relations are true at every instant, so by
dividing(2)by(1), we get
Es/ Ep=Ns/ Np______________ (3)
Ifthe transformer is assumed to be 100%efficient (no
energy losses), the input power is equal to the output power,
and since P = IE,
IpEp
=
IsEs_______________(4)

8. Therefore, from (3) and(4)
Ns/ Np= Es/ Ep= Ip/ Is= K
Where, N is calledTurn Ratio or Transformation Ratio

9. I.Step Up Transformer
In a Step up transformer, low A.C. Voltage is converted to high A.C.
Voltage. Here, the secondary coil has greaterno. of turns (Ns> Np), but
carries less current compared to primary (Is< Ip)
Ns/Np> 1, i.e. Turn Ratio (K) is greater than 1
In order to transmit the voltage from the Power Plant or Generation
Stationover long distances,it is stepped up using a Stepup
Transformer. This voltage with increased levels is then transmitted to
a distribution station.
Illustration

10. II.Step Down Transformer
In a Step down transformer, high A.C. Voltage is converted to low A.C.
Voltage. Here, the secondary coilhas lesser no. of turns (Ns< Np), but
carries more current compared to primary (Is> Ip)
Ns/ Np< 1, i.e. Turn Ratio (K) is less than 1
At the distribution station, the high voltage from power station is
reduced using a Step down Transformer. The voltagewith decreased
level is then made ready for consumer use.
Illustration

11. III.Efficiency
Efficiency of a transformer is defined as the ratio of output
power to the input power. i.e.
η = output power / input power = EsIs/ EpIp
Thus in an ideal transformer,where there is no power losses, n=1
But in actual practice, there are many power losses; therefore
the efficiency of transformer is less than one.

12. IV.Energy Loses
Following are the major sources of energy loss in a transformer:
1.Copper loss: Energy loss in the form of heat in the copper
coils of a transformer. This is due tojoule heating of
conductingwires.
2.Eddy Current:Energy loss in the form of heat in the iron core
of the transformer. This is due to formation of eddy currents
in iron core. It is minimized by taking laminated cores.
3.Leakage of magnetic fluxoccurs inspite of best insulations.
Therefore, rate of changeof magnetic flux linked with each
turn ofsecondaryis less than the rate of change of magnetic
flux linked with each turn ofprimary.
4.Hysteresis loss: Loss of energy due to repeated
magnetization and demagnetization of the iron core when
A.C. is fed to it.
5.Magneto striationi.e. humming noise of a transformer

13. V.Uses of Transformers

1.In voltage regulator for Television, Refrigerator,
Computer, Air Conditioner etc.
2.A step down transformer is used for welding purposes.
3.A step down transformer is used for obtaining large
current.
4.A step up transformer is used for the production of X-
Rays and NEON advertisement.
5.Small transformers are used in Radio sets, telephones,
loud speakers and electric bells etc.
6.Transformers are used in the transmissionsof A.C. over
long distances.

14. Apparatus Required:
Iron Rod
Copper Wire
Voltmeter
Ammeter

15. Circuit Diagram:
Procedure
1.Takethick iron rod and cover it with a thick paper and
wind a large number of turns of thin Cu wire on thick paper
(say 60). This constitutes primary coil of the transformer.
2.Cover the primary coil with a sheet of paper and
wound relatively smaller number ofturns (say 20) of
thick copper wire on it. This constitutes the secondary
coil. It is a step down transformer.

16. 3.Connectprimaryto A.C main and measure the input
voltage and currentusing A.C voltmeter and ammeter
respectively.
4.Similarly, measure the output voltage and current
throughsecondaryand record the observations.
5.Now connectsecondaryto theA.C main, which now
becomes a step up transformer,and again measure
voltage and current through primary and secondary coil.
6.Repeat the abovesteps by changingthenumber of
turns in primary and secondary coil.

17. Observation:
Result
The ratioNs/Npis equal to the ratiosEs/ Epand
Ip/ Is
Turn Ratio,Ns/Np=
Efficiency=
Sl.
No.
NpNS
Turn
Ratio
K =
Ns/Np
Input Output
Es/ EpIp/ Is
Efficiency
η=
Poutput/ Pinput
EsIs/EpIp
Voltage
Ep
Current
Ip
Power
P=EpIp
Voltage
Es
Current
Is
Power
P=EsIs

18. Conclusion
1.The output voltage of the transformer across
the secondary coil depends upon the ratioofthe no.
of turns(Ns/Np)
2.The ratioNs/Npis equal to the ratiosEs/ Epand
Ip/ Is
3.There is aloss of power between input and
output coil of a transformer.

19. Precautions
1.All connection must be tight and proper.
2.While taking the readings of current and voltage
the A.C should remain constant.
SourcesOf error
1.Values of current can be changed due to heating
effect.
2.Eddy current can change the readings.

20. Bibliography
1)NCERT Textbook class 12
2)NCERT Physics Lab Manual
3)www.yahoo.co.in
4)www.scribd.com
5)https://www.electronicshub.org/step-down-
transformer/

21. THE
END