Physics Project

PHYSICS PROJECT
Topic- AC Generator
Session:-2024-25
SUBMITTED BY:
Basant kumar
Class XII
(SCIENCE)
ACKNOWLEDGEMENT
It would my utmost pleasure to

express my sincere thanks to my physics
teacher Mr. Bhuree Singh Chahar in
providing a helping hand in this project.
His valuable guidance and support and
supervision all through this project are
responsible for attaining its present form.
I would also like to thank my parents and

Friends who helped me a lot in my
project.
CERTIFICATE
This is to certify that Basant Kumar, a

student of Class XII has successfully
completed the project under the
guidance of Mr. Bhuree Singh Chahar
during the academic year 2019-20 in
partial fulfillment of physics practical
examination conducted by CBSE.
Sub.Teacher Principal Examiner

INDEX

●
ACKNOWLEDGEMENT PAGE 2
●
CERTIFICATE PAGE 3
●
INTRODUCTION PAGE 5
●
PRINCIPLE OF AC PAGE 6
GENERATOR
●
CONSTRUCTION OF AC PAGE 7
GENERATOR
●
CIRCUIT DIAGRAM PAGE 8
●
THEORY PAGE 9
●
WORKING OF GENERATOR PAGE 10
●
EXPRESSION OF PAGE 11
INSTANTANEOUS EMF PRODUCED
●
APPLICATION OF AC GENERATOR PAGE 13
●
BIBLIOGRAPHY PAGE 14
Introduction
A.C. Generator means Alternating
current generator. It is a device which is
used to convert mechanical energy
into electrical energy.
A.C. generator forces electric current

to flow through an external circuit. The
source of mechanical energy may be a
reciprocating or turbine steam engine,
water falling through a turbine or
waterwheel, an internal combustion
engine, a wind turbine, a hand crank,
compressed air, or any other source of
mechanical energy.
Principle of A.C. Generator
It is based on the principle of
electro-magnetic induction,
i.e., whenever amount of magnetic flux
linked with a coil changes, an e.m.f. is
induced in the coil.
The direction of current induced is given
by Fleming’s right-hand rule.
Construction of A.C. Generator
The A.C. Generator is consist of four main parts :
(1) THE COIL (ARMATURE) :

A rectangular coil ABCD consist of a large number
of turns of copper bound over a soft iron core is called
armature. The soft iron core is used to increase the
magnetic flux.
(2) MAGNETIC FIELD :

It is usually a permanent sponge magnet having
concave poles. The armature is rotated of a magnet so
that axis of the armature is perpendicular to magnetic
field lines.
(3) SLIP RINGS :

Slip rings are the magnetic rings, which are connected
to the terminal of the armature. These rings are
rotated with the coil and these are used to draw the
current from the generator.
(4) BRUSHES :
The brushes B1 & B2 just touches the slip rings. They
are not rotating with the coil and these brushes lead
to the output of load resistance.
Circuit Diagram
Theory
1. The strong magnetic field is produced by a current flow
through the field coil of the rotor.
2. The field coil in the rotor receives excitation through the

use of slip rings and brushes.
3. Two brushes are spring-held in contact with the slip rings

to provide the continuous connection between the field coil
and external circuit.
4. The armature is contained within the windings of the

stator and is connected to the output.
5. Each time the rotor makes one complete revolution, one

complete cycle of AC is developed.
6. A generator has many turns of wire wound into the slots

of the rotor.
7. The magnitude of AC voltage generated by an AC

generator is dependent on the field strength and speed of
the rotor.
8. Most generators are operated at a constant speed;

therefore, the generated voltage depends on field excitation
or strength.
Working of an A.C. Generator
The coil is rotated in the anti-clockwise

direction. In the first half rotation the arm AB is
moving outward and CD is moving inward. So
the e.m.f. is induced in the arm AB from A to B.
And in the arm CD from C to D. After half
rotation (in the second half). The arm CD is
moving outward and AB is moving inward. In
this time current is induced in arm CD from D to
C. And in arm AB from B to A. In the second-half
rotation, the current direction is changing so in
this generator AC is produced.
Expression for Instaneous
e.m.f. produced
Let position of the coil at any time t.

It's making angle θ with vertical. If w is
uniform angular speed of the coil.
Then, θ =ωt
B be the strength of magnetic field n

be the number of turns in the coil and A
area of the coil then magnetic flux with
the coil in this position is given by :
Φ = nBA Cosθ = nBA Cos ωt.

Differentiate w.r.t. time:-
Maximum value of e.m.f. So 𝜺,

ε = εºsin(ɷt)
Result:-
Hence, maximum value of instantaneous e.m.f. in an AC
Generator is given by
ε = εºsin(ɷt)
Applications of A.C. Generator
1. Aircraft auxiliary power generation, wind
generators, high-speed gas turbine generators.
2. Hybrid electric vehicle (HEV) drive systems,

automotive starter generators.
3. An ac generator, or 'alternator', is used to

produce ac voltages for transmission via the grid
system or, locally, as portable generators.
4. All of our household appliances run on ac

current.
Ex: Refrigerator, washing machines, oven, lights,
fan, etc.
5. The main advantage of AC is ease of power

distribution.
It is more efficient to use high voltage to distribute
power, but it is not safe to have high voltage at
home. It is easy to step up (and step down) AC
voltage using a transformer.
Bibliography
• C.B.S.E. Lab manual

• Help of Physics Teacher
• NCERT Textbook
• Websites:-
●
www.Wikipidea.com
●
Chat GPT.

Physics Project

Uploaded by

Copyright:

Available Formats

Physics Project

Uploaded by

Document Information

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Physics Project

Uploaded by

Copyright:

Available Formats

PHYSICS PROJECT

It would my utmost pleasure to

I would also like to thank my parents and

This is to certify that Basant Kumar, a

Sub.Teacher Principal Examiner

A.C. generator forces electric current

(1) THE COIL (ARMATURE) :

(2) MAGNETIC FIELD :

(3) SLIP RINGS :

2. The field coil in the rotor receives excitation through the

3. Two brushes are spring-held in contact with the slip rings

4. The armature is contained within the windings of the

5. Each time the rotor makes one complete revolution, one

6. A generator has many turns of wire wound into the slots

7. The magnitude of AC voltage generated by an AC

8. Most generators are operated at a constant speed;

The coil is rotated in the anti-clockwise

Let position of the coil at any time t.

B be the strength of magnetic field n

Φ = nBA Cosθ = nBA Cos ωt.

Maximum value of e.m.f. So 𝜺,

2. Hybrid electric vehicle (HEV) drive systems,

3. An ac generator, or 'alternator', is used to

4. All of our household appliances run on ac

5. The main advantage of AC is ease of power

• C.B.S.E. Lab manual

You might also like