Aditya Academy Secondary
Physics Project
AISSCE
Session- 2016-17
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- Reeshav Bhattacharyya
Class-XII Roll No-36 Section- E
CERTIFICATE
This is to certify Reeshav Bhattacharyya is a student of Outgoing batch of Class XII of session 2016-2017 from Aditya Academy Secondary
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
ACKNOWLEDGEMENT
I would like to express my special thanks of gratitude to my teachers Mr. Arindam Kr. Bose and Mrs. Chaitali Chatterjee 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.
INDEX
1: Certificate Page-1
2: Acknowledgement Page-2
3: Introduction Page-3
4: Aim, Apparatus Required, Theory Page-4
5: Circuit Diagram, Procedure Page-5
6: Observations Page-6
7: Result, Precautions, Sources of Error. Page-7
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 =μ 0 μ r N2 A
I
Where μ r= Relative magnetic permeability of magnetic material, μ r= 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
I rms =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= I2 rmsZt
The brightness of bulb i.e. Heat generated in bulb is
H= I2 rmsZt
Or, P=H/t= I2 rmsZ
P= I2 rms(R2 + ω2L2)½
Circuit Diagram
Procedure
Make all connections as shown in circuit diagram.
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).
Record the current in A.C. ammeter and see the brightness of bulb.
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.
Now, switch off the supply and decrease the frequency of A.C. source (say 50 Hz).
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.
Again insert the iron in the core of coil and note the current and brightness. The current and brightness both decreases.
Repeat the steps 5, 6 and 7 for different frequency of A.C. source(say 40 Hz,30 Hz and 20 Hz).
Observations
Least Count Error= A.
Zero error of ammeter= A.
Range of ammeter= A.
S No.
Frequency of applied voltage(Hz)
Current in ammeter without iron rod in coil (A)
Current in ammeter with iron rod in coil (A)
1.
60
2.
50
3.
40
4.
30
5.
20
Result
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.
The current in the circuit increases on decreasing the frequency of applied voltage and vice-versa. Therefore, the brightness of bulb increases.
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.