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KENDRIYA VIDYALAYA NO_2

TPKM MADURAI
2022-2023
SUBMITTED BY

UNDER THE GUIDANCE OF

Mrs. Uma karpooram
Pgt physics

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 Class xii a 2022-2023
Bonafide Certificate
This is to certify that this project entitled
“THE FACTORS AFFECTING THE CAPACITANCE
OF PARALLEL PLATE CAPACITORS” is a record of
bonafide work carried out by in
KENDRIYA VIDYALAYA No.2 TPKM MADURAI.

PRINCIPAL

INTERNAL EXAMINER EXTERNAL EXAMINER

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 PHYSICS INVESTIGATORY
PROJECT

THE FACTORS AFFECTING THE

CAPACITANCE OF PARALLEL PLATE
CAPACITORS

name:

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 Acknowledgement

First and foremost, praises and thanks to the God, the

Almighty, for His showers of blessings throughout my project
work to complete it successfully.
I would like to express my deep gratefulness to our school
teachers for their dynamism, vision, sincerity and motivation
which have deeply inspired me. My earnest thankfulness to our
Principal Mr. A. JERALD ARUL, whose constant support
encouraged us in all our educational endeavors. My sincere
gratitude to my Project guide and our physics teacher
Mrs. Uma Karpooram for giving me the opportunity to do the
project and providing invaluable guidance throughout this project
for its successful completion.
I am extremely grateful to my family for their love, prayers,
caring and sacrifices for educating and preparing me for my
future. Finally, my thanks go to all the people who have
supported me to complete the project work directly or indirectly

Yours sincerely :
Roll Number :

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 Table Of Contents

S.NO TOPIC PAGE NUMBER

1 OBJECTIVE

2 INTRODUCTION

3 APPARATUS REQUIRED

4 FORMULA

5 CONSTRUCTION

6 PROCEDURE

7 OBSERVATION

8 CONCLUSION

9 APPLICATION

10 PRECAUTION

11 BIBLIOGRAPHY

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 OBJECTIVE

TO STUDY
THE FACTORS AFFECTING
THE CAPACTANCE OF
PARALLEL PLATE CAPACITORS

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 Introduction
Capacitance
Capacitance is the ability of a component or circuit to collect and store energy
in the form of an electrical charge. Capacitors are energy-storing devices
available in many sizes and shapes . Capacitance is a function only of the
geometry of the design of the capacitor, e.g., the opposing surface area of the
plates and the distance between them, and the permittivity of
the dielectric material between the plates.

For many dielectric materials, the permittivity and thus the capacitance, is
independent of the potential difference between the conductors and the total
charge on them.

The SI unit of capacitance is the farad (symbol: F), named after the English

physicist Michael Faraday .

C =q ÷ V

Where, C is capacitance

q is charge

v is electric potential

Capacitance in electric circuits is deliberately introduced by a device called

a capacitor.  It was discovered by the Prussian scientist Ewald Georg von
Kleist in 1745 and independently by the Dutch physicist Pieter van

Musschenbroek at about the same time, while in the process of investigating

electrostatic phenomena. They discovered that electricity obtained from an
electrostatic machine could be stored for a period of time and then released.

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A capacitor, also called a condenser, is thus essentially a sandwich of two plates
of conducting material separated by an insulating material, or dielectric. Its
primary function is to store electrical energy. Capacitors differ in the size and
geometrical arrangement of the plates and in the kind of dielectric material
used. Hence, they have such names as mica, paper, ceramic, air, and electrolytic
capacitors. Their capacitance may be fixed or adjustable over a range
of values for use in tuning circuits.

The capacitance of the majority of capacitors used in electronic circuits is

generally several orders of magnitude smaller than the farad. The most common
subunits of capacitance in use today are microfarad (mF), nanofarad
(µF), picofarad (pF), and, in microcircuits, femtofarad (fF). However, specially
made supercapacitors can be much larger (as much as hundreds of farads), and
parasitic capacitive elements can be less than a femtofarad.

Capacitance can be calculated if the geometry of the conductors and the

dielectric properties of the insulator between the conductors are known.
Once a positive charge is put unto a conductor, this charge creates an electrical
field, repelling any other positive charge to be moved onto the conductor; i.e.,
increasing the necessary voltage. But if nearby there is another conductor with a
negative charge on it, the electrical field of the positive conductor repelling the
second positive charge is weakened (the second positive charge also feels the
attracting force of the negative charge). So due to the second conductor with a
negative charge, it becomes easier to put a positive charge on the already
positive charged first conductor, and vice versa; i.e., the necessary voltage is
lowered.
As a quantitative example consider the capacitance of a capacitor constructed of
two parallel plates both of area A separated by a distance d. If d is sufficiently
small with respect to the smallest chord of A, there holds, to a high level of
accuracy.

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A capacitance meter is a piece of electronic test equipment used to measure
capacitance, mainly of discrete capacitors. For most purposes and in most cases
the capacitor must be disconnected from circuit.

Many DVMs (digital volt meters) have a capacitance-measuring function. These

usually operate by charging and discharging the capacitor under test with a
known current and measuring the rate of rise of the resulting voltage; the slower
the rate of rise, the larger the capacitance. DVMs can usually measure
capacitance from nanofarads to a few hundred microfarads, but wider ranges are
not unusual. It is also possible to measure capacitance by passing a known high-
frequency alternating current through the device under test and measuring the
resulting voltage across it (does not work for polarised capacitors).

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 APPARATUS REQUIRED

 Capacitor plate with different area

 Capacitor stand
 LCR Meter with connecting wire
 Battery [9 volt]
 Different dielectric [ex: glass]

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 FORMULA

FACTORS AFFECTING CAPACITANCE

There are three major factors that can affect the value of capacitance in a

conductor ;

 The area of the plate used.

 The dielectric used

 Conductors

 The distance between the two parallel plate

C = ε0A/d
C= Capacitance in Farads

ε0 = Absolute Permittivity of dielectric

A = Area of the capacitor plates

d = Distance between plates in meters

When dielectric is introduced

C = ε(ε0A)/d
ε = Permittivity of dielectric medium

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 Construction

i. Make sure you have all the apparatus.

ii. Place the capacitor plates in the capacitor stand.

iii. Connect the wire to multimeter and connect the same wire to the
capacitor plates.

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 PROCEDURE

i. DIFFERENCE IN AREA
After construction of the circuit ,take the reading of the capacitor of the
area 400 cm^2 and change the area of the capacitor.

ii. DIFFERENCE IN DISTANCE BETWEEN THE CAPACITOR PLATES

Keep the area of the capacitor constant and change the distance between
the capacitor plates for example: 0.4 cm, 0.8 cm, 1.2 cm… (Note the
Reading in the multimeter )

And change the area of the capacitor plate and change the distance
between the capacitor plates for example: 0.4 cm, 0.8 cm, 1.2 cm… (Note
the Reading in the multimeter )

iii. DIFFERENT IN DIELECTRIC AT SAME DISTANCE

Take the capacitor plates with area 400cm^2 and change the dielectric
medium between the capacitor plates. Note the reading.

iv. DIFFERENT IN DIELECTRIC AND ALSO DIFFERENT IN

DISTANCE BETWEEN THE PLATES
Now Take the capacitor plates with area 400cm^2 and change the
dielectric medium and also the distance between the capacitor plates.

For example : In the same area keep the distance between the capacitor plates as
1 cm and keep different types of dielectric(air,glass, polyethelene plastic)
between the plates.

keep the distance between the capacitor plates as 2 cm and keep different types
of dielectric(air,glass, polyethelene plastic) between the plates. Continue this
process with varying the distance between the capacitor plates and the
dielectric.

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 OBSERVATION

i. DIFFERENCE IN AREA

S.NO AREA OF THE PARALLEL PLATE CAPACITANCE

CAPACITOR
1 400 cm^2 0.126 nF
2 766 cm^2 0.196 nF

ii. DIFFERENCE IN DISTANCE BETWEEN THE CAPACITOR PLATES

.

S.NO DISTANCE BETWEEN CAPACIANCE CAPACITANCE

THE PARALLEL PLATES [400 CM] [766]
1 0.4 0.258 0.313
2 0.8 0.108 0.112
3 1.2 0.069 0.078
4 1.6 0.045 0.062
5 2.0 0.038 0.053

iii. DIFFERENCE IN DIELECTRIC AT SAME DISTANCE

S.NO DIELECTRIC USED CAPACITANCE

1 AIR 0.132 nF
2 POLYESTEREN PLASTIC 0.180 nF
3 GLASS 0.226 nF
4 PLYWOOD 0.278 nF
5 PAPER 0.146 nF
6 PLASTIC 0.166 nF

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iv. DIFFERENCE IN DIELECTRIC AND ALSO DIFFERENCE IN
DISTANCE BETWEEN THE PLATES

S.NO DISTANCE BETWEEN DIELECTRIC USED CAPACITANCE

THE PARALLEL PLATE
CAPACITORS
1 1 AIR 0.120
2 1 GLASS 0.222
3 1 POLYETHELENE 0.165
PLASTIC
4 2 AIR 0.060
5 2 GLASS 0.082
6 2 POLYETHELENE 0.076
PLASTIC
7 3 AIR 0.050
8 3 GLASS 0.056
9 3 POLYETHELENE 0.054
PLASTIC
10 4 AIR 0.044
11 4 GLASS 0.046
12 4 POLYETHELENE 0.044
PLASTIC
13 5 AIR 0.038
14 5 GLASS 0.040
15 5 POLYETHELENE 0.038
PLASTIC

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 Conclusion

i. As the area of capacitor increases capacitance of the parallel plate

increases.

ii. As the distance between the capacitor plates increases the capacitance of
the parallel plate decreases.

iii. As the dielectric changes the capacitance changes.

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 APPLICATIONs

i. Capacitors are used to store energy.

ii. By studying about the factors affecting the capacitors we can increase
the area of capacitor plates and decrease the distance of the capacitors
to increase the capacitance.

iii. Capacitors are specially constructed with low-inductance and high-

voltage functionalities to fulfill massive electric current levels for
many pulsed power devices. These devices may hold electromagnetic
gadgets, generators (especially Marx generators), pulsed lasers, and
particle accelerators.

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 Precautions

 Do not charge by higher current or higher voltage than specified

 Do not use nor leave the capacitors neither in direct sunlight nor in high-
temperature areas.

 Do not use new and used capacitors together.

 Do not use different types of capacitors together.

 Do not discharge by force.

 Do not heat, disassemble, nor dispose off in fire.

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 BIBLIOGRAPHY
Books

1. K.L. Gomber and K.L. Gogia, Pradeep’s Fundamental Physics,

Pradeep Publications, 2022.
2. Physics Text Book for class XII, National Council of Educational
Research and Training, 2021.

Webliography

i. https://electricalacademia.com/basic-electrical/factors-
affecting-capacitance/
ii. https://en.wikipedia.org/wiki/Capacitance
iii. https://engineeringslab.com/tutorial_electrical/factors-
affecting-capacitance
iv. https://www.allaboutcircuits.com/textbook/direct-current/
chpt-13/factors-affecting-capacitance/

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