Resistance of a Wire :: Papers

Resistance of a Wire Aim: - I hope to find out how resistance of a wire is affected. Prediction: - I predict that as the length of the wire increases the resistance will also increase. Scientific Knowledge: - ======================= A wire is a bundle of metal strips coated in plastic. The plastic can vary in colour and connect to different terminals These are: - ------------ ÂÂ · Black = negative terminal ÂÂ · Red = positive terminal ÂÂ · Blue = neutral terminal ÂÂ · Green and yellow = earth terminal ÂÂ · Brown = live terminal The material varies because it has free electrons, which are able to flow through the wire. The number of the electrons depends on the amount of electrons in the outer energy shell of the atoms, so if there are more or larger atoms then there must be more electrons available. If the material has a high number of atoms there will be a high number of electrons causing a lower resistance because of the increase in the number of electrons. Also if the atoms in the material are closely packed then the electrons will have more frequent collisions and the resistance will increase. Resistance is measured in Ohm's (ÃŽÂ ©). Ohm's Law The law actually says that the resistance of a metal conductor is the same whatever the current - unless it's getting hotter. However most people think of these equations when the law gets mentioned: V = IR V is Voltage in Volts, I is Current in Amps and R is resistance in Ohms. If the length of the wire is increased then the resistance will also increase as the electrons will have a longer distance to travel and so more collisions will occur. Due to this the length increase should be proportional to the resistance increase. If the wires width is increased the resistance will decrease. This is because of the increase in the space for the electrons to travel through.