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# Investigating the Resistance of a Piece of Wire

Extracts from this document...

Introduction

-Physics Coursework-

Investigating the Resistance of a Piece of Wire

Introduction

The purpose of this experiment is to investigate the resistance of a piece of wire. ‘Resistance’, according to the Oxford Encyclopaedia, is the act of withstanding action against something, or opposing a force. It is the hindrance to the flow of charge. For an electron, the journey from terminal to terminal is not a direct route. It is a zigzag path which results from countless collisions with fixed atoms within the material. Resistance is calculated by dividing the potential difference (voltage) by the current. Resistance is measured in ohms (Ω). The resistivity of a metal is the physical property of a material to resist or oppose the movement of charge through the material. This can be calculated by using the following equation:

Where:

L: Length (m)

A: Cross Sectional Area (m2)

R: Resistance (Ohms)

Ρ(Rho): Resistivity (Ohm/Metre)

The resistance of a wire depends on several factors. The temperature, length, material, and thickness of the wire all affect its resistance. These are the variables of the experiment.

Middle

3.1

7.2

25

0.62 A

3.0 V

4.8

0.75 A

2.9

4.6

We decided to use Constantan for our real experiment because it had a greater resistance than Nickel Chrome, which would mean that temperature would have less of an effect on its resistance, making our investigation more accurate.

Prediction

I predict that the greater the length of wire, the greater the resistance of that wire will be. The length of the wire and the resistance of the wire should be directly proportional. This is because if resistance occurs as the result of collisions between charge carriers and the atoms of the wire, then there is likely to be more collisions in a longer wire. More collisions would mean more resistance. If the other variables stay constant, like the temperature and strength of the battery, the graph of my results should show a straight line.

Length of Wire (cm)

Variables

The controlled variables will be the room temperature and the wire material, because both will have an effect on the resistance if they are not controlled. The dependant variable would be the resistance, because it is dependant on the length of wire.

Conclusion

Alternative Investigations

There are a few other investigations which could have been carried out to investigate the resistance of wire. One obvious one could be to change the thickness of the wire. This would be carried out the same way as this experiment (the circuit would be set up similarly) however instead of changing the length of the wire each time the thickness of the wire would be changed. For example the thickness could be changed by 0.1mm each time, so the resistance would be measured for wires of the following thicknesses: 0.1mm, 0.2mm, 0.3mm, 0.4mm, all the way to 1mm. After the results for this have been found they would be tabulated and plotted on a graph, the only difference being that the x-axis would be showing the width (mm). I would predict that the thickness of the wire would also be directly proportional to the resistance, as the thinner the wire, the less space electrons have to pass through.

This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

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