Investigating Resistance of a Wire

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Investigating Resistance of a Wire

INTRODUCTION

This investigation is about find the resistance of a wire. Resistance

is the slow-down of the flow of an electric current around a circuit

so that energy is required to push the charged particles around the

circuit. The circuit itself can resist the flow of particles if the

wires are either very thin or very long.

e.g. The filament across an electric light bulb. Resistance is

measured in a unit called an ohm (Ω). In 1826, Georg Ohm discovered

that: the current flowing through a metal wire is proportional to the

potential difference (p.d) across it (providing the temperature

remains constant). The formula for calculating resistance is:

Resistance, R=p.d across the wire (V)/current through the wire (I)

R=V/I

There are four factors affecting resistance:

•length

•cross-sectional area

•material

•temperature

Electricity has a lot of different uses. It can:

•heat things up

•magnetise things

•produce light

•break down some solutions and compounds.

Electric charge is measured in coulombs (C). Positive charges are

called protons, and negative charges are called electrons.

Electric current is the moving electrons through a conductor of

electricity. Electric current is measured in amperes or amps (A).

A statistical analysis of the experiments will be done in this

investigation.

AIM

To find out how the length of a wire affects the resistance in an

electric current.

HYPOTHESIS

It is predicted that as the length of wire increases, the resistance

will increase. I predict this because, the longer a wire is, then the

more time it will take for electrons to go through. The resistance

also depends on the material and cross-sectional area. As the

cross-sectional area increases, the resistance decreases. This is

because if the cross-sectional area of a wire is high, then the

electrons can pass through quicker than if the wire was thin.

The length of the wire will make a difference. This is because when

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