# An experiment to find how the resistance of a wire changes when the length is changed.

An Experiment To Find How The Resistance Of A Wire Changes When The Length Is Changed

## Aim

In this experiment we hope to see how the resistance of a wire changes when the length is changed.

## Prediction

In this experiment I predict that when the length of a wire increases the resistance will also increase. Thus length is directly proportional to the resistance.

## Hypothesis

I think my prediction is true because the equation for resistance is voltage divided by current. So the voltage and current directly affect the resistance. The resistance should be directly proportional to the length, as two 10cm wires should have the same resistance as a 20cm wire. Ohm’s law states that a current flowing through a metal conductor is directly proportional to the voltage across its ends (provided all other conditions are constant). So I know that if we add a variable – in this case length – resistance will change. I expect that the longer the wire, the higher the resistance. Electrons colliding with atoms in the wire cause resistance. The longer the length of wire, the more atoms there will be, so the more chance there is of the electrons to collide. Thus causing higher resistance. The resistance and the length should be directly proportional to each other therefore. In a long piece of wire there are more atoms so there is less room for the electrons to get through. The electrons bump into the atoms and lose some of their energy. However in a short piece of wire, there are fewer atoms. This means that it is easier for the electrons to move through the wire.

Apparatus

We used the following apparatus: _ A meter rule, 30 Nichrome wire, seven other wires, a variable resistor, a 6 volt battery and two crocodile clips.

The measuring instruments in the apparatus list are as follows: _

## Method

We set the circuit, shown above, and ran a current through it. Then we decided what lengths of wire we should be using and the intervals between each one. Then we put ...