Resitence of Wire

Aim

I am going to be studying the resistance of wire. The purpose of this investigation is to see how the length of wire affect the dependent variable, resistance.

Prediction

I predict that, as the length of the wire doubles, the resistance will also double, This means that the length will affect the resistance.

Hypothesis

Resistance is caused by electrons bumping into ions. If the length of the wire is doubled, the electrons bump into twice as many ions so there will be twice as much resistance. So If the cross-sectional area of the wire doubles there will be twice as many ions and twice as many electrons bumping into them, but also twice as many electrons getting through twice as many gaps. If there are twice as many electrons getting through, as there is twice the current, the resistance must have halved. This means that

I am assuming that the temperature is kept constant and that the material is kept constant.

Method

Equipment needed:

1 x Power Pack (to give varied voltage)

1 x Voltmeter

1 x Ammeter

5 x wires (with crocodile clips)

wire of varied length and thickness

First, set up the experiment as shown above. Turn on the power and set the power pack . Record the voltage and current, varying the length of the wire in intervals of 10cm from 10cm to 40cm.

The equation for resistance = V/I

Results

Conclusion

I conclude that, as the length of a wire is increased, the resistance also increases (provided the thickness of the wire is kept constant. So

The theory behind these conclusions are:

As the length doubles the resistance doubles. Resistance is caused by electrons bumping into ions. If the length of the wire doubles, the electrons bump into the ions twice as much so the resistance will double.