1. The student conducted an experiment to determine the variation of resistivity in different materials. Resistivity was measured for aluminum wire, copper wire, iron wire, and manganin wire. 2. Calculations were shown to determine the resistivity for each material using measurements of resistance, length, thickness, and area. 3. The resistivity increased in the order of aluminum wire, copper wire, iron wire, and manganin wire respectively. This follows the known trend that metals have lower resistivity than alloys.

1. KENDRIYA VIDYALAYA NO.1,
NARIMEDU,MADURAI
PHYSICS INVESTIGATORY PROJECT (2022-2023)
STUDY OF VARIATION OF RESISTIVITY
OF DIFFERENT MATERIALS
PROJECT REPORT
PHYSICS
UNDER GUIDANCE OF : MRS . LATHA (PGT-PHYSICS)
SUBMITTED BY : T . RITWICK PRASANA (XII-B)

2. BONAFIDE CERTIFICATE
This is to certify that this project entitle "STUDY OF VARIATION OF
RESISTIVITY OF DIFFERENT MATERIALS" is a record of bonafide work
carried out by T . RITWICK PRASANA in partial fullfillment of the
requirements in PHYSICS prescribed by CBSE for AISSCE 2022-2023 in
the school Kendriya Vidyalaya, No 1, Narimedu, Madurai-625 002.
ROLL NUMBER:
DATE :
PRINCIPAL :
INTERNAL EXAMINER :
EXTERNAL EXAMINER :

3. DECLARATION
I hereby declare that the project work entitled
STUDY OF VARIATION OF RESISTIVITY OF
DIFFERENT MATERIALS
Submitted to KENDIYA VIDYALAYA NO.1, MADURAI
For the subject of "PHYSICS" under guidance of
Mrs.LATHA, PGT (PHYSICS), is a record of original
work done by me. I further declare that this project
report or any part of this has not been submitted
elsewhere for any other classes.)
• DATE: NAME : T . RITWICK PRASANA
• PLACE : KV No.1 MADURAI

4. ACKNOWLEDGEMENT
I express my sincere gratitude to our beloved
Principal. Mr. P.SELVARAJ for encouraging me to
take this topic as my investigatory project.
I am very much thankful to our Physics teacher
Mrs. LATHA (PGT-PHYSICS) for her constant
guidance, suggestion and keen interest in every
stage of this project.

5. SYNOPSIS
S. No. Title Page No.
1. INTRODUCTION 1
2. AIM 4
3. APPARATUS 4
4. THEORY 5
5. PROCEDURE 8
6. OBSERVATION 10
7. CALCULATIONS 12
8. RESULT 15
9. PRECAUTION 16
10 SOURCES OF ERROR 16
11. CONCLUSION 17

6. INTRODUCTION
Ohm's Law states that the current flowing through a conductor is directly
proportional to the potential difference applied across its ends, provided the
temperature and other physical conditions remain unchanged.
Vαl
V=IR
where V is Voltage in volts (V), R is Resistance in ohm (Ω), is Current in
Ampere (A). Ohm's law is an empirical relation. However some materials do
not obey Ohm's law, these are called non-ohmic. Ohm's law holds for circuits
containing only resistive elements for all forms of driving voltage or current,
regardless of whether the driving voltage or current is constant (DC) or time-
varying such as AC. At any instant of time Ohm's law is valid for such circuits.
Ohm's law is not applicable for unilateral electrical elements like diodes and
transistors as they allow the current to flow through in one direction only. For
non-linear electrical elements with parameters like capacitance, resistance
etc the voltage and current won't be constant with respect to time making it
difficult to use Ohm’s law.

7. The Electrical resistance of an object is a measure of its opposition to the flow
of electric current. The SI unit of electrical resistance is the ohm (2). The
resistance of an object depends in large part on the material it is made of
objects made of electrical insulators like rubber tend to have very high
resistance while objects made of electrical conductors like metals tend to
have very low resistance a wire's resistance is higher if it is long and thin, and
lower if it is short and thick. All objects show some resistance, except for
superconductors, which have a resistance of zero. The resistance of objects of
these materials is constant. The resistance of a given object depends
primarily on two factors: What material it is made of, and its shape. For a
given material, the resistance is inversely proportional to the cross-sectional
area.

8. Electrical resistivity is a fundamental property of a
material that quantifies how strongly it resists
electric current. A low resistivity indicates a
material that readily allows electric current.
Resistivity is commonly represented by the rho (p).
The SI unit of electrical resistivity is the ohm metre
(m). A conductor such as a metal has low resistivity.
An insulator like glass has high resistivity. The
resistivity of a semiconductor is generally
intermediate, but varies widely under different
conditions, such as exposure of the material to
electric fields or specific frequencies of light, and,
most important, with temperature and composition
of the semiconductor

9. AIM
To determine the variation of resistivity of different materials
APPARATUS REQUIRED
1. Resistance wire
2. Voltmeter of appropriate range
3. Ammeter of appropriate range
4. Battery (Battery Eliminator)
5. Rheostat
6. Metre Scale
7. One way Key
8. Connecting wires
9. A piece of sand paper
10. Screw guage

10. Aluminium building wiring is a type of electrical wiring for
residential construction or houses that uses aluminium electrical
conductors. It provides a better conductivity to weight ratio than
copper, and therefore is also used for wiring power grids,
including overhead power transmission lines as well as for power
wiring of some airplanes. It has cost and weight advantages over
copper wires.

11. A copper wire is a single electrical conductor made of copper. It can be insulated or
uninsulated. A copper cable is a group of two or more copper wires bundled together in
a single sheath or jacket. Copper wire and cables is used in power generations, power
transmission, power distribution, telecommunications and countless types of electrical
equipment. It has been useful ever since telegraphs and electromagnets were invented.
Copper is the most widely used conductor in many kinds of electrical wiring. Copper has
the lowest resistance to the flow of electricity of all non-precious metals. Electrical wiring
in buildings is the most important market for the copper industry. About half of all
copper mined is used to make electrical wire and cable conductors.
Iron wire is a resistance type wire often used for the manufacture of nails, wire mesh
and all kinds of fencings. Soft iron wire can be used for many tasks, and is most often
used for various types of fixation. It can be treated like a super string. It does what string
does, but also put in any position, it’s stronger, twisted and knotted, made into
pockmarks and more. The galvanized iron wire, is mainly used for fencing of various
purposes. Numerous small metal objects can be made from rigid iron wire. Some
examples are clips, books, tool stands, simple hinges & door catches and many other
items. Iron wire can be used as bolt substitutes with a lower maximum load. It can be
used for lightweight or temporary shelf supports.

12. Manganin is an alloy of typically 84% copper, 12% manganese,
and 4% nickel. It was first developed by Edward Weston in 1892.
Manganin foil and wire is used in the manufacture of resistors,
particularly ammeter shunts, because of its virtually zero
temperature coefficient of resistance value and long term
stability. Manganin wire is also used as an electrical conductor in
cryogenic systems, minimizing heat transfer between points
which need electrical connections. It is also used in gauges for
studies of high pressure shock waves such as those generated
from the detonation of explosives because it has low strain
sensitivity but high hydrostatic pressure sensitivity

13. PROCEDURE
1. Draw the circuit diagram.
2. Arrange the required materials on the table.
3. Make the connections according to the circuit diagrams.
4. Determine the least count of the voltmeter and ammeter, and also note the zero error, if any.
5. Insert the key K, then slide the rheostat contact and see that the ammeter and voltmeter are working
properly.
6. Adjust the sliding contact of the rheostat such that a small current passes through the resistance coil
or the resistance wire.
7. Note down the value of the potential difference (V) from the voltmeter and current (1) from the
ammeter.
8. Shift the rheostat contact slightly so that both the ammeter and voltmeter full divisions readings.
9. Record the readings of the voltmeter and ammeter.
10. In each case V/I is calculated, which gives the resistance R of the resistor and it is found as a
constant.
11. Take at least three sets of independent observations.
12. Cut the resistance wire at the points where it leaves the

14. Terminals, stretch it and find its length by the meter
scale
13. Record the observations

15. OBSERVATIONS
1. ALUMINIUM WIRE :
Current Voltage Resistance
2. COPPER WIRE :
Current Voltage Resistance
3. IRON WIRE :
Current Voltage Resistance

16. 1. MANGANIS WIRE
Current Voltage Resistance

17. CALCULATIONS
• 1. ALUMINUM WIRE:
• Length-68 cm=0.68 m
• Thickness 0.0066 m
• Area 0.00000028 m²
• Mean Resistance (0.5+0.66+0.75)/3 =1.91/3 =0.63 ohm
• Resistivity-0.63(0.000028)/0.68 -0.00001764/68 -2.65*10 ohm m
• 2. COPPER WIRE:
• Length=42 cm-0.42 m
• Thickness 0.0049 m
• Area-0.00000077 m
• Mean Resistance (0.5+0.54+0.6)/3
• =1.64/3
• =0.54 ohm

18. Resistivity=0.54(0.00000077)/0.42
=0.00000041/0.42
=1.68*10-8 ohm m
3.IRON WIRE:
Length= 21 cm= 0.21 m
Thickness = 0.0054 m
Area = 0.00000022 m²
Mean Resistance = (1.3+1.001+1)/3
=3.301/3
= 1.1 ohm
Resistivity=1.1(0.00000022)/0.21
=0.000000242/0.21
=9.71*10-8 ohm m
4.MANGANIN WIRE:
Length = 57 cm-=0.57 m
Thickness = 0.0066 m
Area= 0.00000019 m²
Mean Resistance =(1.3-1.5+1.3)/3
=4.1/3
=1.36 ohm

19. Resistivity=1.36(0.00000019)/0.57
=0.00000025/0.57
=48.2*10-8 ohm m

20. RESULT
The resistivity of the wires are as follows:
1. Aluminum wire- 2.65*10-8 ohm m
2. Copper wire- 1.68*10-8 ohm m
3. Iron wire-9.71*10-8 ohm m
4. Manganin wire- 48.2*10-8 ohm m
Material Resistivity, ρ (Ω-m)
Superconductors 0
Metals 10-8
Semiconductors Variable
Electrolytes Variable
Insulators 1016
Superinsulators ∞

21. PRECAUTION
1. Connections should be tight.
2. Short circuiting should be avoided.
3. The plug should be inserted only while taking
observations otherwise current would cause
unnecessary heating in the circuit.
4. Voltmeter and ammeter should be of proper
range.
SOURCES OF ERROR
1. The connections might be loose.
2. High resistance rheostat may be used.
3. The wire may not have uniform thickness

22. CONCLUSION
Ohm's law, in the form above, is an extremely useful equation in the
field of electrical/electronic engineering because it describes how
voltage, current and resistance are interrelated on a "macroscopic"
level, that is commonly, as circuit elements in an electrical circuit. The
main application of Ohm's Law is used when building electrical
devices. Most appliances need a certain amount of voltage and current
to operate. To figure out the most efficient way to get the proper
current, Ohm's Law is used. Ohm's Law can tell you how much
resistance you need to establish a certain current with a certain
amount of voltage. Also Ohm's Law is used to figure out which
resistors are needed. Without Ohm's Law, we wouldn't be able to
figure out how much resistance is needed in a circuit, and therefore
either too much or too little current or voltage would be produced.

23. BIBILIOGRAPHY
• www.cbse.net.in
• www.wikipedia.com
• www.ncertbooks.com
• www.google.com