Physics Project
AISSCE Session
2020-2021
Topic :
To study the factor on which the
Self Inductance of a coil
depends by observing the effect
of this coil, when put in series
with a resistor (bulb) in a circuit
fed up by an A.C. source of
adjustable frequency.
submitted by-
Name- TRISIYA.K
Class-XII Roll No- Section
INDEX
1) Certificate
2) Acknowledgement
3) Introduction
4) Aim
5) Apparatus Required
6) Theory
7) Circuit Diagram
8) Procedure
9) Observations
10)Result
11)Precautions
12)Sources of Error.
CERTIFICATE
This is to certify K.TRISIYA is a student of
Outgoing batch of Class XII of session 2020-
2021 from GURUKSHETRA PUBLIC SCHHOL
Thereby certifying that the above student has
done the project title “To study the factor on
which the Self Inductance of a coil depends by
observing the effect of this coil, when put in
series with a resistor (bulb) in a circuit fed up by
an A.C. source of adjustable frequency” under
our supervision.
Signature of Teacher:
ACKNOWLEDGEM
ENT
I would like to express my special thanks
of gratitude to my teacher Mr.
S.rajapandian who gave me the golden
opportunity to do this wonderful project
on the topic which also helped me in
doing a lot of Research and I came to
know about so many new things I am
really thankful to them.
Secondly I would also like to thank my
parents and friends who helped me a lot
in finalizing this project within the
limited time frame.
Signature of Student:
Introduction
There are four basic factors of inductor construction
determining the amount of inductance created. These
factors all indictate inductance by affecting how much
magnetic field flux will develop for a given amount of
magnetic field force (current through the inductor’s wire
coil.
The factors are:-
• NUMBER OF WIRE WRAPS, OR “TURNS” IN
THE COIL.
• COIL AREA.
• COIL LENGTH.
• CORE MATERIAL.
Aim
To study the factor on which the Self
Inductance of a coil depends by observing
the effect of this coil, when put in series
with a resistor (bulb) in a circuit fed up by
an A.C. source of adjustable frequency.
Apparatus Required
A coil of large turns, A.C. source of
adjustable frequency, an electric bulb, (6 V)
A.C. ammeter of suitable range, rheostat, a
soft iron rod, one way key, connecting wires
etc.
Theory
Self Inductance is the property of a coil which oppose the
change in current through it. The Self Inductance of a coil (long
solenoid) is
L =μ0μr N2A
I
Where μr= Relative magnetic permeability of magnetic material,
μr=μ
μ
0
N= Total number of turns in solenoid
A= Area of cross section of solenoid
l= Length of solenoid
Hence, the Self Inductance depends upon
• No. of turns (N), L α N2
• Geometry of coil, L=A , L α 1/l
• Nature of core material, L= μ
When an inductor is connected in series with a resistor
(bulb) with a variable source of frequency, then current
flowing in the bulb is
Irms=E rms
Z
Where Z= (R2 +ω2L2)½=Impedance of the A.C. Circuit
Here R= Resistance of bulb
L= Self Inductance of coil
ω = 2πf = Angular frequency of A.C. source.
The brightness of bulb i.e. Heat generated in bulb is
H= I2rmsZt
The brightness of bulb i.e. Heat generated in bulb is
H= I2rmsZt
Or, P=H/t= I2rmsZ
P= I2rms(R2 + ω2L2)½
Circuit Diagram
Procedure
1.Make all connections as shown in
circuit diagram.
2.Switch on the A.C. supply and adjust the
constant current in the circuit by using the
variable resistor (R1) (let frequency of
source is 60 Hz and voltage is 6V).
3.Record the current in A.C. ammeter and
see the brightness of bulb.
4.Now, put the soft iron rod inside the
inductor core and record the current in A.C.
ammeter and again check the brightness of
bulb. The current and brightness both
decreases.
5.Now, switch off the supply and decrease
the frequency of A.C. source (say 50 Hz).
6.Again switch on the supply and adjust the
current in circuit at same constant voltage
6V by using the rheostat. Note the current in
ammeter and brightness of bulb. The current
and brightness both will increases.
7.Again insert the iron in the core of coil and
note the current and brightness. The current
and brightness both decreases.
8. Repeat the steps 5, 6 and 7 for different
frequency of A.C. source(say 40 Hz,30 Hz
and 20 Hz).
OBSERVATION
Least Count Error= A.
Zero error of ammeter= A.
Range of ammeter= A.
S No. Frequency of applied Current in ammeter Current in ammeter
voltage(Hz) without iron rod in with iron rod in coil
coil (A) (A)
1. 60
2. 50
3. 40
4. 30
5. 20
Result
1. As you decrease the frequency of applied voltage
the current in the circuit increases vice versa.
Therefore, the brightness of bulb increases.
2. The current in the circuit decrease on inserting the
iron rod in the core of coil at constant frequency of
applied voltage and brightness of bulb decreases and
vice-versa.
Precautions
• The coil should have large number of turns.
• Current should be passed for a small time to
avoid the heating effect.
• There should not be parallax in taking the
reading of ammeter.
Sources of Error
• The resistance of circuit may
increases slightly due to heating effect
of current.
• There may be eddy current in soft iron
coil.
