What Factors affect the resistance of a wire?

* Temperature

* Voltage

* Material

In this experiment, I will be changing the length of the wire, to see how this will affect the resistance of the wire.

Method

First a length of wire over a metre long is measured using a metre rule. The positive crocodile clip is attached at 0cm. And the negative is moved up and down the wire, stopping at 20, 40, 60, 80 and 100cm.

Each time, I will read the ammeter and the voltmeter to work out the resistance (R = V/I). This is using 30 SWG wire. Other variables, voltage, thickness, and temperature will be kept constant throughout the experiment.

Apparatus

The apparatus I will be using for the experiment are:

* Ammeter

* Voltmeter

* 1 meter of 30 SWG wire

* 2 crocodile clips

* Variable resistor

* Power supply

* Wires

* Metre ruler

Diagram

Fair testing

To make the experiment a fair test, I will make sure that I use the same apparatus, I will also make sure that the thickness and the material of the wire I am using is at a constant. I will repeat the experiment, and use the best results for my final write up.

Safety

Whilst doing my experiment, I must take safety into consideration. Before using the power pack, the pointer should be at 0 volts. It is important to be careful while using the power supply. While handling live wires, it is essential to be careful. The voltage should be kept low for safety, and for when the wires heat up.

Prediction

I think that if the length increases, then the resistance will also increase. I think this is because if the wire is longer, there are going to be more atoms, so it is more likely that the electrons are going to collide with the atoms. So if the length doubles, the resistance should also double. This is because if the length is doubled, the number of atoms will double, resulting in twice the number of collisions, slowing the electrons down, and increasing the resistance.

Results

Length of wire (cm)

Voltmeter reading

Ammeter reading

Resistance

00

3.6

0.30

2

80

3

0.34

8.8

60

2.8

0.40

7

40

2.2

0.45

4.8

20

0.56

.7