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# Preliminary Experiment - testing the resistance of a wire.

Extracts from this document...

Introduction

Lydia Boast 29th April 2003

Preliminary Experiment.

Before starting my preliminary experiment I had to choose my wire, I decided to use Constantan because I wanted the resistance to stay the same even if the wire did get quite hot, and even though the Constantan does change if the wire gets very hot, I am not planning on letting it get this hot as this would be a risk. As you can see compared to two other resisting components, it stays the most constant in its resistance.

I have also decided the thickness of my wire; I looked at a range of thickness’ and eventually decided on 28swg. I decided this because the thinner wire, 36swg, was too thin and would snap very easily when doing the experiment, which would mean you would have to keep on changing your wire giving you useless results. The resistance for the thin wire is too large for this experiment. The thicker wire, 16swg, was too thick as it had a lot of kinks in it that you wouldn’t have been able to get out, the resistance was too low for the thick wire as well.

Middle

## Theory

Current - current is the rate of flow of charge around a circuit.

Charge - charge is measured in coulombs.

1amp is the current flowing when a charge of 1 coulomb flows for a time of 1 second.

The property of a substance in virtue of which the passage of an electric current through it is accompanied with a flow of energy, - an electric resistor.

Length- Components offer resistance to the current. For a particular voltage the length of wire will determine the resistance. Diagram A shows that it will take twice the amount of time for the current to pass through the wire when it is twice the length as shown in Diagram B, than in Diagram A. This is because it has to pass through twice the amount of molecules. The resistance will be directly proportional to the length. When you double the length you double the resistance and when you triple the length you triple the resistance

Thickness- Diagram A is half the thickness of Diagram B yet it still has the same amount of particles. The current therefore will take twice

Conclusion

I do not think that doing any more results in our experiment would have made it any more accurate. I feel that the only way to make it more accurate would be to use a different method – perhaps were we had a bar that did not bend in place of the wire. Or we could hang the wire from a stand with a weight on the end of it forcing it to straighten and then clip the crocodile clips onto the wire while it is hanging making the results better.

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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