# What Factors affect the resistance of a piece of wire(evaluation missing)

Essay by Manipulated April 2004

Aim:

The aim of this is to investigate how the length of a wire affects the resistance of it.

Prediction:

I predict that the longer the piece of wire, the greater the resistance will be. This is due to the idea of the free moving electrons being resisted by the atoms in the wire. In a longer piece of wire, there would be more atoms for the electrons to collide with and so the resistance would be greater. The relationship between the wire length and the resistance should be directly proportional. This is because in a wire twice the length of another wire there would be double the amount of atoms causing the resistance.

An example of this would be in a 20cm wire. The electrons would have to travel double to distance if it have to go through a 10cm wire. This would in turn double the amount of atoms that the electrons would collide with and then resistance would double.

Plan:

In this investigation a simple circuit will be set up to read the voltage and current when the length of the wire changes. The length will range from 10cm - 100cm (1m) with intervals of 10cm. The length of the wire will be changed by moving the crocodile clip across the wire on a ruler. We decided that the best thickness of wire to use would be 30swg.This is because a thicker wire would cause too much heat, and the resistance of a thinner wire would be high and difficult to measure. The reason for this is that a thicker wire has less resistance, because there is more room for the electrons to travel through it.

We did preliminary tests to ensure that the wire did not get too hot, and how many cells to...