Looking at the factors that affect the resistance of a piece of wire.

Planning

The key variables

The variables that will affect my experiment are, the length of the wire, the cross sectional area, the temperature and the material.

Fair Test (Length):

To make sure that my experiment is carried out fairly, I will have to make sure that the length of the wire stays the same throughout the experiment because if it doesn’t the resistance may be varied. The temperature must remain the same throughout the experiment because if the temperature is varied, the resistance will also vary.

Only one type of metal wire can be used because different metals conduct different amounts of electricity and different metals may have more or less resistance, the metal I will be using is constantan.

Fair Test (Thickness):

The cross sectional area must remain the same because if it isn’t the results may vary. The temperature must remain the same throughout this experiment because if the temperature is varied the resistance will also vary. Only one metal wire can be used because different metals conduct different amounts of electricity, the metal I will be using is constantan.

There are two factors to my experiment therefore there will be two predictions.

Prediction 1

As the length increases the resistance increases. I know this because the wire tends to resist the movement of electrons in it. As the length increases, the number of atoms increases so as the atoms vibrate fewer electrons pass through because the electrons lose energy.

Prediction 2

As the cross sectional area increases the resistance increases. When the current starts the electrons have more places to pass through the atoms because there are holes in where the electrons can ...