The document summarizes the working principles of transformers. It explains that a transformer works on the principle of mutual induction to convert alternating voltages from high to low or vice versa. Key points include: - Transformers have a primary coil connected to a voltage source and a secondary coil wound around an iron core. - The changing magnetic field in the primary induces a voltage in the secondary. - The ratio of primary to secondary turns determines whether it is a step-up or step-down transformer. - Transformers experience energy losses such as copper losses, iron losses, and hysteresis losses, reducing their efficiency.

1. VV

2. It is heartily thanks to the principal mam of
for the given facilities and
opportunity. Primarily I would thank god being able to complete
this project with success. Then I would like to thank my physics
teacher Mrs. DEEPIKA , whose valuable guidance has been the
once that helped me patch this project and make it full proof success
, her suggestions and her instructions has served as the major
contributor towards the completion of 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 project .
 Last but not the least I would like to thank my friends
who have helped me a lot .

3. CERTIFICATE
oThis is hereby to certify that the original and genuine
investigation work has been carried out to investigate
about the subject matter and the related data
collection and investigation has been completed
sincerely and satisfactorily by ISHA GOYAL of class
12th‘B’ of S.A. JAIN SENIOR MODEL SCHOOL
,regarding her project titled
o “TO STUDY THE NO. OF TURNINGS IN THE
SECONDARY AND PRIMARY COIL OF
TRANSFORMER”.

4.  INTRODUCTION
 THEORY
 IN A STEP DOWN
TRANSFORMER
 IN A STEP UP
TRANSFORMER
 EFFICIENCY
 AIM
 APPARATUS
REQUIRED
 PROCEDURE
 ENERGY LOSSES
 USES OF TRANSFORMERS
 NUTSHELL
 PRECAUTIONS
 SOURCES OF ERROR

6. • The Transformer is a device used for converting a
low alternating voltage to high alternating voltage
and vice versa . A Transformer based on principle
of mutual induction according to this principle , the
amount of magnetic flux linked with a coil changing,
an e.m.f is induced in the neighbouring coil. A
Transformer is most widely used device in both low
and high current circuit. A Transformer is an
electrical device which is used for changing the
A.C. voltages . A Transformer which increases the
voltages is called STEP UP TRANFORMER . A
transformer which decreases the voltages is called
STEP DOWN TRANFORMER .

7. Figure 1 represents the essential elements for a transformer - a magnetic
core, with a primary and secondary coil wound on the limbs of the magnetic
core.
Figure 1. A Basic Transformer
An alternating voltage (Vp) applied to the PRIMARY creates an alternating
current (Ip) through the primary.
This current produces an alternating magnetic flux in the magnetic core.
This alternating magnetic flux induces a voltage in each turn of the primary
and in each turn of the SECONDARY.
As the flux is a constant e.g. the same in both primary and secondary: -
Vp = const Np
Vs = const Ns
FIGURE 1

8. This equation shows that a transformer can be used to step up or step down
an ac voltage by controlling the ratio of primary to secondary turns. (Voltage
transformer action)
.It can also be shown that: -
Primary Volt Amperes = Secondary Volt Amperes
Vp Ip = Vs Is
This equation shows that a transformer can be used to step up or step down
an ac current by controlling the ratio of primary to secondary turns. (Current
transformer action)
It will be noted that there is no electrical connection between the primary and
secondary windings.
A transformer therefore provides a means of isolating one electrical circuit
from another.
These features - voltage/current transformation and isolation, cannot be
obtained efficiently by any other means, with the result that transformers are
used in almost every piece of electrical and electronic equipment in the world.

9. • Es<E so k<1 hence Ns<Np
• If Ip= value of primary current at the same instant
• AndIs=value of secondary current at this instant,
then
• Input power at that instant=EpIp
• And
• Output power at the same instant=EsIs
• If there are no losses of power in the transformer,
then
• Input power=Output power or Ep Ip =Es Is or
Es/Ep=Ip/Is=K

10. Es>E so K>1
Hence,
Ns>Np
As K>1, so Ip>Is or Is<Ip
i.e. current in secondary is weaker when secondary
voltage is higher . Hence , whatever we gain in voltage
, we lose current in the same ratio. Similarly it can be
shown, that in a step down transformer, whatever we
lose in voltage, we gain in current in the same ratio,
Thus a step up transformer in reality step down the
current and step down transformer steps up the

11. EFFICIENCY
efficiency of a transformer is defined as the ratio of output power to the inputpower
= esis/epip
thus in an ideal transformer , where there is no power losses , = 1
but in actual practice , there are many power losses , therefore efficiency of transformer is less than one
=
Output power/Input power

12. To study the number of turnings in secondary and primary coil of transformer .
AIM OF THE EXPERIMENT
APPARATUS REQUIRED
Iron Rod
Copper wire
Voltmetre
Ammetre

13. PROCEDURE
 Take thick iron rod and cover it with a thick paper and wind a large no. Of
turns of thin copper wire on thick paper . This constitutes primary coil of the
transformer.
 Cover the primary coil with a sheet of paper and wound relatively smaller
no. Of turns of thick copper wire on it. This constitutes the secondary coil.
It is a step down transformer.
 Connect P1, P2 to ac main and measure the input voltage and current using
ac voltmeter and ammeter respectively.
 Similarly, measure the output voltage and current through S1 and S2.
 Now connect S1 and S2 to ac main and again measure voltage and current
through primary and secondary coil of step up transformer.
 Repeat all steps for other self made transformers by changing no. Of turns
in primary and secondary coil.

14. ENERGY LOSS
Following are types of energy loss in a transformer
1. Copper loss is the energy loss in the form of heat in the copper coils of a
transformer. This is due to joule heating of conducting wires.
2. Iron loss is the energy loss in the form of heat in the iron core of the
transformer. This is due to formation of eddy currents in the iron core . It is
minimised by taking laminated cores.
3. Leakage of magnetic flux occurs inspite of best of best insulation. Therefore,
rate of change of magnetic flux linked with each turn of S1S2 is less than the
rate of change of magnetic flux linked with each turn of P1P2.
4. Hysteresis loss is the loss of energy due to repeated magnetism and
demagnetism of the iron core when A.C. is fed to it.
5. Magneto striation i.e. Humming noise of a transformer.

15. USES OF A
TRANSFORMER
A step down transformer is used for obtaining large
current.
Transformers are used in transmission of ac over
long distances.
In voltage regulator for T.V. ,refrigerator, and
stabilized power supplies.
Small transformers are used in radio sets ,
telephones and loud speakers etc.
A step down transformer is used for welding
purposes.
A step up transformer is used for the production of
x rays and NEON advertisement.

16. NUTSHELL

17. PRECAUTIONS
Keep safe yourself from high voltage.
While taking the readings of current the A.C. should remain
constant.
SOURCES OF ERROR
Values of current can be changed due to heating effect.
Eddy currents can change the reading.

18. BIBLIOGRAPHY
 LABORATARY MANUAL OF PHYSICS
 www.wikipedia.com
 Google
 Phys.org