this documement is specialy for class12 student on topic To study various factors on which the internal resistance/EMF of a cell depends. 

1. NAME - AYUSHMAAN PANDEY
CLASS- XII 'A'
ROLL NO.
Saraswati vidya mandir sr.
sec. school

3. of coil depend
Objective
To study the factors on which the Self Inductance
of a coil depends by observing the effect of this coil,

4. when put in series with a resistor (bulb) in a circuit
fed up by an A.C. source of adjustable frequency.

6. I would like to express my special thanks of gratitude to my
teacher Mrs.Shailendra sir who have given 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.

7. INDEX
 Introduction
 Aim
 Apparatus Required

8.  Theory
 Circuit Diagram
 Procedure
 Observations
 Result

9.  Precautions
 Sources of Error
Introduction

10. There are four basic factors of inductor
construction determining the amount of inductance
created. These factors all indicate inductance by
affecting how much magnetic field flux will develop

11. 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.

12. • COIL LENGTH.
• CORE MATERIAL.

14. Aim
To study the factor on which the Self Inductance of
a coil depends by observing the effect of this coil,

15. when put in series with a resistor (bulb) in a circuit
fed up by an A.C. source of adjustable frequency.
Apparatus Required

16. 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.

17. Theory
Self Inductance is the property of a coil which
opposes the change in current through it. The Self
Inductance of a coil (long solenoid) is

18. L =μ0μr N2 A
Where μr= Relative magnetic permeability of
magnetic material,
μr = μμμ°

19.  N= Total number of turns in solenoid
 A= Area of cross section of solenoid
 l= Length of solenoid
Hence, the Self Inductance depends upon

20. • No. of turns (N), L α N2
• Geometry of coil, L=A , L α 1/l
• Nature of core material, L= μ

21. 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

22. Z
Where Z= (R2 + ω2L2)½=Impedance of the A.C.
Circuit
R= Resistance of bulb
L= Self Inductance of coil

23. ω = 2πf = Angular frequency of A.C. source.
The brightness of bulb i.e. Heat generated in bulb
is
H= I2rmsZt

24. The brightness of bulb i.e. Heat generated in bulb
is
H= I2rmsZt
Or,
P=H/t= I2rmsZ

25. P= I2
rms(R2
+ ω2
L2
)½

27. Procedure
 Make all connections as shown in circuit
diagram.

28.  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).

29.  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

30. 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).

31.  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.

32.  Again insert the iron in the core of coil and note
the current and brightness. The current and
brightness both decreases.

33.  Repeat the steps 5, 6 and 7 for different
frequency of A.C. source (say 40 Hz,30 Hz and
20 Hz).

34. Fig 1.1: Experimental setup of experiment.

35. Observations
 Least Count Error= 0 A.
 Zero error of ammeter =0 A.
 Range of ammeter = 0-5 A.

36. 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 1.8
2. 50 2.5 2.3

37. Result
3. 40 2.9 2.6
4. 30 3.4 3.25
5. 20 4.1 4

38. • 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.

39. • The current in the circuit increases on decreasing
the frequency of applied voltage and vice-versa.
Therefore, the brightness of bulb increases.
Precautions

40. • 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.

41. Sources of Error
• The resistance of circuit may increases slightly
due to heating effect of current.

42. • There may be eddy current in soft iron coil.
Bibliography
 https://www.google.com/url?sa=t&source=web&rct=j&url=https
://en.wikipedia.org/wiki/Inductance&ved=2ahUKEwj08Iniro7lAh
UJqI8KHTf0AnYQFjADegQIBBAB&usg=AOvVaw2P7iDjtFkUu
M4sVZ3Xvuee

43.  https://www.google.com/url?sa=t&source=web&rct=j&url=https
://www.ukessays.com/essays/education/self-induction-and-
mutual-
induction.php&ved=2ahUKEwj08Iniro7lAhUJqI8KHTf0AnYQFj
ASegQIAxAB&usg=AOvVaw101-
LPrKSTgDiDwgKYZPHV&cshid=1570596884921

44.  https://www.google.com/url?sa=t&source=web&rct=j&url=https
://phys.libretexts.org/Bookshelves/Electricity_and_Magnetism/
Book%253A_Electricity_and_Magnetism_(Tatum)/10%253A_E
lectromagnetic_Induction/10.92%253A%2509Self_Inductance
&ved=2ahUKEwjWhcLMsY7lAhVMdCsKHdOGAD4QFjAFegQ
IBRAB&usg=AOvVaw2BBdsgbr538c7M-b_dO4e9