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How length of a wire affects resistance.

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Introduction

                                                          Laura Boyes 11D1.

How length of a wire affects resistance.

Background knowledge.

The atoms in metals don’t move, they can only move to and fro about a fixed point. This means the electrons in a piece of wire struggle to squeeze through the atoms. It is harder for them to get through a longer wire as it has more atoms. This means the resistance is higher in a piece of wire, as I will prove in my experiment. Copper ions are held together by the attractions to the electrons, this is because they are positively charged. Molecules or covalent substances have no more free electrons and therefore don’t conduct, they don’t have any charged particles so they are unable to conduct. So these substances won’t work in the experiment. I will be using a metallic piece of wire, as metals are good conductors of heat and electricity because the free electrons can take in heat energy. They are malleable (can be hammered into different shapes easily)

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Middle

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Electrons must squeeze through the gaps in the atoms and this is done easier in the shorter piece of wire than the longer one because there are less atoms, which shows that resistance is greater in the longer piece of wire, shown above. This is shown in the diagram above.

 Prediction.

I think that the longer piece of wire is the resistance will be larger. This is because longer pieces of wire contain more non – moving atoms so the electrons cannot squeeze through the atoms.

Apparatus.

1m of resistance wire, crocodile clips, power pack, ammeter, voltmeter, sellotape, metre ruler.

Method.

  1. Collect the apparatus shown above. Plug in the power pack and set it to a suitable voltage – this will ensure the wire doesn’t overheat.
  1. Set the crocodile clips to 10 cm on the ruler, make sure there is sellotape on the ruler to keep the wire stuck down.
  1. Measure the voltage and current, record the results and turn off the power pack so the wire doesn’t overheat.
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Conclusion

     I could make my experiment better by taking more results down to ensure it was accurate. I could use a different diameter of wire or a different type. To make the investigation better I could do some preliminary work to give me some background information, this would improve my investigation.

     My experiment was good enough to support my conclusion because I made the experiment as fair as possible, and didn’t make many errors. It also agrees with my prediction I made in the beginning.

    To extent the investigation further, I could use different lengths of wire; I could also use a different diameter or type of wire. I would use a good conductor of electricity for the wire, gold would be a good metal to use but it isn’t practical as it is expensive. This could improve my experiment.

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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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