Investigate how the resistance changes in a wire of different lengths.

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Andrew                                      The Resistance in a Wire                            16th November 

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Variables: - There are many variables for this experiment: the material of wire, the voltage, the width of the wire, and the length of the wire.

Factors to observe: - You could see how the temperature changes and how the resistance changes due to the variables.

Aim: - to investigate how the resistance changes in a wire of different lengths. This means my variable will be the length and factor to observe will be the resistance. In order to make it a fair test, all possible variables (except the length) must be kept constant. If I change the material of the wire half way through, its structure might be different to the one used previously i.e. there might be more particles for the electrons to bump into, so there would be a sudden jump in resistance between the two. If I accidentally changed the voltage, by moving it either higher or lower, their would be more or less current passing through, that that of the rest of the experiment, so it wouldn’t be a fair test of resistance and there would be large jumps in my measurements.

Prediction: - Once my results have been collected, the graph will look like this:

                      Resistance (ohms)    

                                                                    Length (cm)

The resistance of the wire will be directly proportional to the length, i.e. as the length doubles, the resistance doubles.

The wire is made up of atoms with protons and electrons. A current is passed along by the moving around of free electrons. As the electrons pass on the current, the bump into fixed particles and the protons, and lose energy as heat and the current slows down. This is resistance. As the wire is lengthened, there would be more protons for the electrons to hit, therefore the resistance will be more.

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In a smaller length of wire, there are fewer collisions between the fewer number of stationary particles and electrons so the wire is cooler, as shown by the path of the electron.

                     

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