# Length affects the resistance

Essay by rabia_s February 2006

Aim:

The aim of my investigation is to investigate how length affects the resistance of a length of wire

The resistance of a wire depends on certain factors. Some of these variables are listed below:

* Length of wire

* Diameter of wire

* Temperature at which wire is at

* The material of which wire is made out of

* The potential difference across circuit

* Cross sectional area

These must be kept constant (except the length of the wire). The three major factors are explained bellow:

1) Temperature When the temperature of a metal increases the resistance of that metal increases. This is because when the temperature increases the atoms of the metal vibrate more vigoursly because of the increase in energy. This means that the electrons have more difficulty getting through the wire as they collide with the atoms which are in their pathway. This increases the amount of collisions therefore there is more resistance.

However it is hard to keep the temperature exactly the same as the room temperature might change from day to day. It is essential to use a low voltage because it means a low current that will not heat up the wires. If a high voltage is used the energy would be in form of heat which would make the experiment unfair. The investigation will be done at room temperature. The temperature cannot be investigated because it is hard to control the range of temperature needed without the correct apparatus.

2) Length of wire The larger the length of the wire, the larger the resistance. This is because there are more atoms from the metal so there is more chance that the electrons would collide with one of the atoms therefore there is more resistance. The length of wire will be variable...