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Investigating Factors that Affect Resistance in Metal.

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Introduction

Investigating Factors that Affect Resistance in Metal Task To investigate how the resistance of a wire is affected by the length of the wire. Background Information Electricity is conducted through a conductor, in this case wire, by means of free electrons. The number of free electrons depends on the material and more free electrons means it has less resistance. For example, gold has more free electrons than iron and, there for gold is a better conductor. The free electrons are given energy and collide with neighbouring free electrons. This happens across the length of the wire and this creates electricity. Resistance is the result of energy loss as heat. Heat occurs when there are collisions between the free electrons and the fixed particles in the metal. These collisions change some of the electricity that the free electrons are carrying into heat. The resistance of a length of wire is calculated by measuring the current in the circuit and the voltage across the wire . These measurements are then applied to this formula: V(voltage) = I (amperes) x R (resistance/ohms) This can be rearranged to: R = V / I Also the thicknes of a wire affects the resistance in a wire, the thicker the wire the less resistance there is, therefor the thinner the wire the more resistance there is. ...read more.

Middle

We placed 1 crocodile clip on 1 end of the wire on the 0cm mark. We then placed the second crocodile clip on the second position, starting at 10cm. We then turned off the power pack, and changed the position of the crocodile clip. We did this so as not to heat up the wire and to keep the results as accurate as possiable, and also for the safety aspect. We did this so no one would be burned on a hot wire, and also so the no sparks would be created by moving the crocodile clip along the wire. All of this is completed at every 10 cm interval. And then restarted on the second wire. We knew to do the intervals at 10 cm intervals as we had first done a trial experiment, and we found that the thickness and the length intervals of the experiment were suitable. This is because the results were not to close together and not to far apart and therefor easy to plat and the thickness of the wire was suitable as they both gave differant readings to eachother. Fair Test We made it a fair test by taking the light bulb out of the circuit so that it didn't affect the resitance and the results. ...read more.

Conclusion

room there is for free moving electrons to move without colliding with other free moving electrons and particles in the wire causing resistance (and heat) to increase. As well as the length and thickness of the wire, temperatur affects the level of resistance as the electrons have more energy making the resistance change. The inaccurate results towards the end of the experiment that did not follow the trend at the begining of the experiment were caused by the increase in temperature of the wire. This is because temperature of the wire alters the levels of resistance, so totaly accurate results could not be given. We could improve the experiment making it more accurate by keeping the temperature of the wire constant. This could b achieved by changing each wire after an experiment or allowing a wire to cool after an experiment. We could also improve the experiment by taking the results 3 or more times and averagin them out. This would lead to much more accurate results. We however could not do this as there was not enough time allocated in class. Further experiments that could be carried out to investigate resistance in wires further could be finding exactly how temperature does affect resistance in a wire, or by taking a wider range of wire diameters than 4mm and 2 mm wires. ...read more.

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