the physics project tht i have made first time in my life which is awesome

1. ACKNOWLEDGEMENT :
I would like to express my sincere thanks and
gratitude to my physics teacher Akash Baidya
for his sincere guidance and advice to complete
my project successfully. Also, I am thankful to him
for providing such an interesting topic for our
physics project I would want to convey my
heartfelt gratitude to sir Akash my mentor, for
his invaluable advice and assistance in completing
my project. He was there to assist me every step
of the way, and his motivation is what enabled me
to accomplish my task effectively. I would also
like to thank all of the other supporting personnel
who assisted me by supplying the equipment that
was essential and vital, without which I would not
have been able to perform efficiently on this
project.
I would also want to thank sir for accepting my
project in my desired field of expertise. I’d also
like to thank my friends and parents for their
support and encouragement as I worked on this
assignment.
DECLARATION :

2. I hereby declare that the work presented in this
project entitled THE FACTOR ON WHICH SELF
INDUCTANCE OF A COIL DEPENDS has been
carried out by me under the supervision of Mr
Akash Baidya. I further declare that this project
has not formed the basis for the award of any
similar title of any Institutions
Name :-Arpita Nandi
Date :-15/11/2022
Certificate:
This is to certify that Arpita Nandi of class 12th
’B’
has successfully completed her project on 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.
as prescribed by Mr Akash Baidya
Submitted by- Arpita Nandi
Submitted to – Akash Baidya

3. Index:
1)Aim
2) Materials Required
3) Introduction
4) Theory
5)Procedure
6)Circuit diagram
7) Observations
8) Observations on table
9)Results
10)Precautions
11)Source of error
12)Bibliography
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.
Materials required:

4. 1)A coil of large turns,
2)a.c. source of
adjustablefrequency,
3)an electrical bulb

5. 4) a.c.ammeter of suitable
range rehostat
5)a softiron rod,

6. 6)one way key,
7) connecting wires etc.

7. Introduction:
In electromagnetism and electronics, inductance
is the property of an electrical conductor by which
a change in current through it induces an
electromotive force in both the conductor itself
and in any nearby conductors by mutual
inductance.
These effects are derived from two fundamental
observations of physics: a steady current creates
a steady magnetic field described by Oersted’s
law, and a time-varying magnetic field induces an
electromotive force (EMF) in nearby conductors,
which is described by Faraday’s law of induction.
According to Lenz’s law a changing electric
current through a circuit that contains inductance
induces a proportional voltage, which opposes the
change in current (self-inductance). The varying
field in this circuit may also induce an EMF in
neighboring circuits (mutual inductance).
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
L =( μ_0 μ_r N2 A)/l

8. 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 in solenoid
Geometry of coil, L A , L 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 )+ ω2 L2 = 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 = I_rme2 Zt
P = H/t = Irms2 Zt

9. P = Irms2 √R2 + ω2 L2
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.

10. 8) Repeat the steps 5, 6 and 7 for different
frequency of A.C. source(say 40 Hz,30 Hz and 20
Hz).
Circuit diagram-
OBSERVATIONS:-
1. Least count of ammeter = 0.05 A.

11. 2. Zero error of ammeter = 0 A.
3. Range of ammeter = 0 – 5 A
Observation table:
Graph-
1) For a given coil say A1 the value of inductive
impedence Z may be calculated by plotting
the values of I vs V along y-axis
The slope of the straight line graph so
obtained gives us the value of Z of the coil at a
fixed frequency
The slope = dV /dI = Z
2)In this way the value of Z and A1 at different
frequencies are worked worked out .

12. Fig- V/I graph for coil A1
Results:
1. The current in the circuit decrease on inserting
the iron rod in the core of coil at constant
frequent of applied voltage and brightness of bulb
decrease and vice-versa.
2. The current in the circuit increase on
decreasing the frequency of applied voltage and
vice-versa. Therefore, the brightness of bulb
increase.

13. Precautions:-
1. The coil should have number of turn.
2. Current should be passed for a small time to
avoid the heating effect.
3. There should not be parallax in taking the
reading of ammeter.
Source of Error:-
1. The resistance of circuit mat increase slightly
due to heating effect of current.
2. There may be eddy current in soft iron coil.
In electromagnetism and electronics, inductance
is the property of an electrical conductor by which
a change in current through it induces an
electromotive force in both the conductor itself
and in any nearby conductors by mutual
inductance.
These effects are derived from two fundamental
observations of physics: a steady current creates
a steady magnetic field described by Oersted’s
law, and a time-varying magnetic field induces an
electromotive force (EMF) in nearby conductors,
which is described by Faraday’s law of induction.
According to Lenz’s law a changing electric

14. current through a circuit that contains inductance
induces a proportional voltage, which opposes the
change in current (self-inductance). The varying
field in this circuit may also induce an EMF in
neighboring circuits (mutual inductance).
Lenz's law is shown by the negative sign in
Faraday’s law of induction:-
which indicates that the induced voltage and
the change in magnetic flux have opposite signs. It
is a qualitative law that specifies the direction of
induced current but says nothing about its
magnitude. Lenz's Law explains the direction of
many effects in electromagnetism, such as the
direction of voltage induced in an inductor or wire
loop by a changing current, or why eddy currents

15. exert a drag force on moving objects in a
magnetic field.
Lenz's law can be seen as analogous to Newton’s
third law in classic mechanics.
For a rigorous mathematical treatment, see
electromagnetic induction and Maxwell’s
equations.
Inductors do this by generating a self-induced emf
within itself as a result of their changing magnetic
field. In an electrical circuit, when the emf is
induced in the same circuit in which the current is
changing this effect is called Self-induction, ( L )
but it is sometimes commonly called back-emf as
its polarity is in the opposite direction to the
applied voltage.
When the emf is induced into an adjacent
component situated within the same magnetic
field, the emf is said to be induced by -induction,
(M) and mutual induction is the basic operating
principal of transformers, motors, relays etc. Self
inductance is a special case of mutual inductance,
and because it is produced within a single isolated
circuit we generally call self-inductance simply,
Inductance.

16. The basic unit of measurement for inductance is
called the Henry, (H) after Joseph Henry, but it
also has the units of Webers per Ampere ( 1 H = 1
Wb/A ).
Lenz’s Law tells us that an induced emf generates
a current in a direction which opposes the change
in flux which caused the emf in the first place, the
principal of action and reaction. Then we can
accurately define Inductance as being: “a coil will
have an inductance value of one Henry when an
emf of one volt is induced in the coil were the
current flowing through the said coil changes at a
rate of one ampere/second”.
In other words, a coil has an inductance, ( L ) of
one Henry, ( 1H ) when the current flowing
through it changes at a rate of one
ampere/second, ( A/s ) inducing a voltage of one
volt, ( VL ) in it.
This mathematical representation of the rate of
change in current through a coil per unit time is
given as:
di/dt (A/s)
Where: di is the change in the current in Amperes
and dt is the time taken for this current change in
seconds. Then the voltage induced in a coil, ( VL )

17. with an inductance of L Henries as a result of this
change in current is expressed as:
VL = -L di/dt (V). Note that the negative sign
indicates that voltage induced opposes the change
in current through the coil per unit time (di/dt).
From the above equation, the inductance of a coil
can therefore be presented as:
Inductance of a Coil
L = VL/(di/dt) = 1volt/(1A/s) = 1Henry
Where: L is the inductance in Henries, VL is the
voltage across the coil and di/dt is the rate of
change of current in Amperes per second, A/s.
Inductance, L is actually a measure of an
inductors “resistance” to the change of the
current flowing through the circuit and the larger
is its value in Henries, the lower will be the rate of
current change.
We know from the previous tutorial about the
inductor, that inductors are devices that can store
their energy in the form of a magnetic field.
Inductors are made from individual loops of wire
combined to produce a coil and if the number of
loops within the coil are increased, then for the

18. same amount of current flowing through the coil,
the magnetic flux will also increase.
So by increasing the number of loops or turns
within a coil, increases the coils inductance. Then
the relationship between self-inductance, ( L ) and
the number of turns, ( N ) and for a simple single
layered coil can be given as:
Self Inductance of a Coil
L = Nφ/I
Where:
L is in Henries
N is the Number of Turns
Φ is the Magnetic Flux Linkage
Ι is in Amperes
This expression can also be defined as the flux
linkage divided by the current flowing through
each turn. This equation only applies to linear
magnetic materials.

19. Conclusion:
After doing this project, I learned alot more about
the factors on which the self -inductance of a coil
depends and equipments and I have researched
on the project i.e., To study the factor on which the
self inductance of a coil depebds by observing the
effect of this coil when put on series : with a
resistors /bulb in a circuit fed up by an ac source
of adjustable frequency I was able to learn from
my other classmates and Teachers. I can organise
information orderly and neatly.
Bibliography:
1) Physics lab manual class 12
2)www.google.com

20. 3) www.seminarsonly.com
4) https://www.seminarsonly.com/Engineering-
Projects/Physics/self-inductance-of-a-coil.php
5) pdfcoffee.com_physics-investigatory-project-pdf-
free.pdf