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Investigating factors affecting the resistance of a wire

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Introduction

Mark Tranham 11 Red Physics AT1 Investigating factors affecting the resistance of a wire? Aim I am investigating what happens to the resistance when you change the length of the piece of wire you are testing. Resistance is the property of any object or substance to resist or oppose flow of an electric current. The quantity of resistance in an electric circuit determines the amount of current flowing in the circuit for any given voltage applied to the circuit, according to Ohm's Law. Ohm's Law is a formulation of the relationship of voltage, current, and resistance, expressed as: Where: V is the Voltage measured in volts I is the Current measured in amperes R is the resistance measured in Ohms Therefore: Potential difference = current x Resistance Hypothesis I predict my results will show that as the length of wire increases, the resistance will increase also. This is because there is a larger amount of wire to travel up and therefore there will be more factors to increase resistance. In a wire there are atoms, which are built up in an arrangement that is fixed because it is a solid. Atoms increase proportionally to the amount of wire; therefore if there is more wire there will be more atoms. Atoms consist of protons, electrons and neutrons. The protons and neutrons make the nucleus of an atom while the electrons circle the outside. ...read more.

Middle

Therefore, this must be kept the same. I will supply no more than 0.6 amps; I learnt this from my trial experiment to keep this a fair test, I will have to change the length of the wire, as this is what I am testing and this will help me obtain my results and draw a valid conclusion. I am going to make three measurements for each length and for each current. I will then take an average and work out the resistance. I am doing this because this will make my results more accurate. My results will be precise to 0.01ohms. I will be using ten different length of wire starting at 10cm and going to 100cm. My experiment is a good way of carrying out my experiment, as it is a fair test and should produce valid results. It allows me to compare results providing an analysis and conclusion. My experiment is also a good way of carrying out the experiment because there is a larger amount of wire to travel up and therefore there will be more factors to increase resistance. In my trial experiment I tested for how large a current I would be able to use without the smallest (least resistant) wire heating up. You are able to tell when a wire is heating up as you obtain variable results. My circuit was set up identically to the one above. ...read more.

Conclusion

This means there can be more atoms over a smaller area or the opposite. Therefore the electrons can have more/less space to get through the atoms. If this were not kept the same this would not have been a fair test. I believe my measurements were accurate enough as they were taken to 0.01��, 0.01A and 0.01V. They were taken by digital ammeters and voltmeters making them more reliable. My results must also have been quite accurate as they allowed me to draw up a valid conclusion, as my results were what I expected and were largely similar. I believe my results allowed me to cover a wide enough range because I took results from ten lengths and this gave me enough to analyse. All my results agree very well with my prediction as when I repeated measurements they were very similar and my results were proportional. My results fit directly onto a line of best fit and had no anomalous results. I think it would be very difficult to improve my experiment as I got very good results. Further experiments that are relevant to my investigation would be to test it over a wider range of lengths to see if there is a slight curve as you increase the lengths or to try the same experiment using a thermistor, a semiconductor diode connected first one way and then the other way round, and a torch bulb. From these different materials I will test how their graphs compare to mine and why they are that way. ...read more.

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