Preliminary Experiment
In this experiment, I am working out whether length affects the resistance of a wire this means I will keep the same the type of wire, the current and as best I can the heat. In the preliminary experiment I need to find a good current to which a considerable difference is seem between the voltages at the different length, but I don’t want the wire to overheat and burn. It was decided to test 0.3A, 0.4A and 0.5A. The design of the circuit also had to be arranged. The voltmeter went across the
Variables
Scientific theory
Certain materials such as copper have many free electrons, making it a good conductor. Other materials have fewer free electrons and substances such as glass, rubber, mica have practically no free electron movement therefore making good insulators as nothing is moving out or in. Between the extremes of good conductors such as silver, copper and good insulators such as glass and rubber lay other conductors of reduced conducting ability, they "resist" the flow of electrons hence the term resistance. Some examples of that type of resistance are: Silver = 9.75 ohms, Copper = 10.55 ohms, Nickel = 53.0 ohms and Nichrome = 660 ohms
The length of the wire will make a difference to the resistance. This is because when you have a long wire, the electrons have to squeeze together for longer to be able to pass through the wire than they do in order to be able to pass through a short wire. I predict that the longer the wire, the greater the resistance. For example, if I had a 30 cm wire and a 60 cm wire, the 60 cm wire would have a resistance twice that of the 30 cm wire. The more the electrons bump together, the higher the resistance
