Investigating the Resistance of a Wire

Investigating the Resistance of a Wire

Planning

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Aim

The aim of my investigation is to investigate how length affects the

resistance of a wire. Resistance is the force, which opposes the flow

of an electric current around a circuit so that energy is required to

push the charged particles around the circuit. Resistance is measured

in ohms. Resistance occurs when the electrons travelling along the

wire collide with the atoms of the wire. These collisions slow down

the flow of electrons causing resistance. Resistance is a measure of

how hard it is to move the electrons through the wire.

Plan of the method to be used:- The resistivity of a wire can be

determined using the equation P= RA/L Where: R:- Is the resistance of

the wire in ohms and can be determined using the equation R=V/I where

V is voltage in volts and I is current in amperes. L:- is the length

of the wire used in metres. A: - Is the cross-sectional area of the

wire in metres square and can be determined using the equation A=

π(d/2 x10 ³)² where d is the diameter of the wire in mm. I will plot a

graph of length on the x-axis against resistance on the y-axis. From

the relation R = PL /A which corresponds to the straight line equation

y=mx+c the graph should be a straight line passing through the origin

where m is the gradient of the straight line graph that corresponds to

P/A. Since the cross-sectional area of the wire can be found by

measuring its diameter. Therefore the resistivity of the wire can be

calculated.

Apparatus list:-

t Battery 1.5V

t Switch

t Metre Rule

t Voltmeter

t Ammeter

t Wire 100cm (under test)

t Crocodile clips

t Connecting wires

t Micrometer

t Sellotape

Apparatus

Range

Sensitivity

Metre Rule

0-100 cm

0.1 cm

Micrometer

0-25 mm