AJMANI INTERNATIONAL
SCHOOL
LAKHIMPUR KHERI
PHYSICS INVESTIGATORY PROJECT
SESSION-(2025-26)
12th A1
TOPIC - ___________________________________
SUBMITTED BY:-
STUDENT’S NAME - ___________________
CLASS -______________
CBSE Roll No. - _____________________
MR ABHAY SHARMA
SUBMITTED TO:-
TEACHER’S NAME-__________________
ACKNOWLEDGEMENT
I wish to extend my heartfelt gratitude to those
who contributed to the successful completion of
myphysicsProject.
I am deeply thankful to my Physics Teacher,
Mr./Ms… … … … … … … … … … for his
guidance and mentor-ship, which were pivotal in
shapingthisproject.
I'd also like to acknowledge our Principal,
Mr. … … … … … … … … . for his unwavering
support and encouragement throughout this
endeavor.
My parents have been my constant source of
support, providingboth emotional and academic
assistance, which was instrumental in this
project'ssuccess.
Student’s Name -
Class -
CERTIFICATE
This is to certify that ………….……………… student
of class ……… of Ajmani International School
has successfully completed the Investigatory
Project entitled on ………………….…………………
under the guidance of Mr./Ms. ………………… for
the academic year (2025-26) in partial
fulfillment of physics practical examination
conducted by CBSE, New Delhi.
Student has taken proper care and shown
utmost sincerity in the completion of this
project. I certify that this project is up to my
expectation and as per the guidelines issued
by CBSE.
Principal’s Signature
….………………………….
Teacher’s Sign. Examiner’s
Sign
….…………………. ……………………….
valuable guidance and support and
supervision all through this project are
responsible for attaining its present
form.
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.
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.
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.
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.
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.
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 :
= nBA Cosθ = nBA Cos ωt.
Differentiate w.r.t. time:-
Maximumvalue ofe.m.f. So 𝜺 ,
ε=ε° sin(𝜔𝑡 )
Hence, maximum value of instantaneous e.m.f. in an AC
Generator is given by
𝜺 = 𝜺 ° sin(𝝎𝒕 )
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.
