An Investigation Into The Resistance of different lengths of wire
In my coursework I intend to determine the relationship between resistance of a circuit and the length of a piece of wire.
Planning 1: Preliminary Work:
I performed preliminary work to evaluate what voltage I was going to use for my proper experiment. The apparatus I will use for the preliminary is the same as I intend to use for my experiment, that is;
ÃÂ· A 1000mm length of wire attached to a 1000mm ruler using a non conductive adhesive
ÃÂ· 2* Multimeters
ÃÂ· 5* Insulated wire connectors with corresponding 2*Crocodile clips.
ÃÂ· 1* Power pack with an available output voltage of above 1v.
The disadvantage of using the same apparatus for both experiments (preliminary and main) is that the wire degrades after use forming a layer of oxide over the wire which makes it difficult to connect on the crocodile clips due to the oxide not being conductive.
The way to remove it is to sand it off, but removing the oxide, and indeed inevitably part of the metal, will make the wire thinner, thus increasing the resistance of the wire. So I will be careful when removing any oxide residue. The advantage of using the same apparatus consistently is that I will avoid having differences in the results by way of inaccuracies in the measuring equipment, resistance differences of the wire etc. This gives 2 immediate advantages, firstly using results from a preliminary experiment e.g. using a thick wire and choosing 1.0V could be a mistake if I then went on to use a thin wire in my experiment and cause a fire with 1.0V. The second is that I will be able to compare the results I get in my proper experiment...