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# Resistance of a wire

Extracts from this document...

Introduction

Variables.

1. Wire length-because the longer the wire the higher the resistance. This is because the electrons have longer to travel there for more collisions will occur.
2. Material-because the type of material will effect the number of free electrons, which are able to flow through the wire. The number of electrons depends on the amount of electrons on the outer shell of the atoms, so if there are more atoms then there are more electrons available. This will cause a lower resistance because of an increase in number of electrons.
3. Wire diameter- because if the wire diameter increases then the resistance will decrease. This is because if the diameter is bigger then it leaves more space for the electrons to travel through. Because of the increased space between the atoms, there will be fewer collisions
4. Temperature- because if the wire is heated up, the atoms in the wire will start to vibrate more rapidly. This will cause more collisions between the atoms and the electrons, due to atoms moving in the path of flowing electrons. An increase in collisions means there will be an increase in resistance.
5. Wire density-because if the wire has a higher density it means the electrons path will be more clogged up, more collisions will occur which means there is a higher resistance.

Research.

Resistance, in electricity, property of any object or substance to resist or oppose the flow of an electrical current.

Middle

Repeat steps 3. – 6. but put the second crocodile clip at 20, 30, 40, 50, 60, 70, 80, 90 and 100.Repeat steps 1. – 7. again for accuracy.

To ensure it is a fair test I am going to use a constant voltage of 2 volts and a constant length of 100cm. There isn’t too much that can go wrong safety wise in this investigation. However there are a couple of things to keep in mind. The scissors for cutting the wire are for no other reason than that. Before using the power pack make sure the pointer is pointing at 0. Do not turn the voltage up too high to avoid the wire heating up. Before the experiment starts all the apparatus must

Conclusion

During my experiment I have noticed several modifications I could make to improve on the Investigation if I was to repeat.

Instead of connecting the voltmeter to the main circuit I would connect it to the wire which is being tested. I would do this so that the voltmeter is measuring the voltage of just the wire being tested and not the wires of the main circuit as well.
To also improve on my results I would use a digital voltmeter instead of an analogue meter. I would do this because a digital voltmeter is a lot more accurate than an analogue because if the needle in the analogue voltmeter is bent then the readings given off will be false whereas a digital voltmeter does not rely on a needle or any other manual movements.
The next modification I would make would be to use pointers instead of crocodile clips , I would do this because pointers would be more accurate. The pointers would be more accurate because the tips have a much smaller area than the crocodile clips giving a more accurate measurement of the length of wire.
As well as making these modifications I would also improve my Investigation by testing the same wire but different widths of that wire. I would do this to expand on my Investigation.

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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