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Resistance of a Wire

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Introduction

Resistance of a Wire Aim: Investigate the factors that affect the resistance of a metal wire. The main factors that affect the resistance in a conductor are: * Length * Temperature * Thickness * Material * Magnetism Resistance is defined as the ratio of voltage to current. Resistance involves collisions of the current-carrying charged particles with fixed particles that make up the structure of conductors (metals in this case). The electromotive force (energy), measured in volts, across a circuit divided by the current, measured in amperes, through that circuit defines quantitatively the amount of electrical resistance. The equation we use to find the resistance of a wire is: Resistance= voltage/current R= V/I In simple words, resistance is the number of volts difference across the object when one amp of current flows. You should recall that voltage is the number of joules of energy transferred by one coulomb of charge, and that current is the number of coulombs of charge passing a place each second. Metals conduct electricity because the atoms in them do not hold on to their electrons very well, and so creating free electrons, carrying a negative charge to jump along the lines of atoms in a wire. ...read more.

Middle

5. Change the thickness of the wire until you have tested them all. 6. Record your results into a table as the one shown below. Results Thickness Resistance (?) Experiment 1 Experiment 2 22swg 1 1.5 24swg 2.5 2.6 26swg 2.6 3.6 28swg 2.8 4.2 30swg 5.5 5 32swg 6.9 7.8 34swg 10 9.8 36swg 14.5 14.5 40swg 32.8 33.8 Error = 0.3 These results show a pattern, which is supported by the hypotheses. As the wire gets thinner the resistance of the wire increases significantly. As I said before this happens because when the wire is thicker then the electrons have more space to go through so they need less energy and the resistance decreases. In both experiments the results were pretty similar, since we tried our best to keep all the variables controlled. There was an increase in the resistance of the wires 40, 26, and 28 from the first experiment to the second. This could have happened because the temperature in the laboratory that day was different, but it is impossible to control the temperature and the results still fit the pattern, so it does not really affect the investigation. All the other results were quite similar in both experiments, since they only varied by 0.5? ...read more.

Conclusion

Also I would try to b more accurate when measuring the length of the wire, so that I could b sure that the length was kept the same with all the wires. I would make sure that none of the wires had been stretched, so that I could be sure that the thickness was the same throughout the length. I would also take more readings so that my results and my graphs could be more accurate, and I would be able to make more accurate conclusions. Also I would repeat the experiment more times, so that if I did something wrong in one of them it would be easy for me to know which set of results is wrong and why it is wrong. Since I only have 2 sets of results it is hard to say why some of the readings are incorrect because it could be either of them that is wrong and there is no way to know which one it is. Although this investigation can be improved, the results are mostly accurate and they all follow the pattern that they should have, so it is possible to make a conclusion. As I have already mentioned in my hypothesis, thinner wires have a higher resistance and thicker wires have a lower resistance, and I have all my data to support this conclusion. Mariana Bustos 10MR ...read more.

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