# The resistance of wire.

Extracts from this document...

Introduction

Aim

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

Prediction

I predict that, as the length of the wire doubles, the resistance will also double, but as the cross-sectional area of the wire doubles, the resistance halves. This means that the length will affect the resistance more than the thickness will.

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 essaybank.co.uk

I am assuming that the temperature is kept constant and that the material is kept constant. We can include this in our equations by adding a constant wweb ebw esebebs ayeb ebba neb kceb ebuk.

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

Controlled variables: wwfa faw esfafas ayfa faba nfa kcfa fauk!

Temperature (room temperature)

Wire material

Dependent variable:

Resistance

Independent variables:

Thickness of wire

Length of wire

Circuit diagram

First, set up the experiment as shown above. Turn on the power and set the power pack so that the voltmeter reads 0.1 volts. Take the reading from the ammeter recording both the current and the voltage. Then do exactly the same again but use voltages of 0.2 volts, 0.3 volts, 0.4 volts and 0.

Middle

Apparatus -Power Supply, Ammeter,Voltmeter,Just over 100cm of E26 Wire,Meter Rule,Two Crocodile Clips,Connecting Wires.

Factors which must stay constant to keep the experiment a fair test

The power supply must stay on 4V,

The wire must be the same thickness,

The surrounding temperature must be constant,

The equipment should be kept the same,

The edge of the crocodile clips should be at the edges measured length.

The Variable factor

The factor that I am going to vary is the length of the E26 wire.

Circuit diagram

## Method

The circuit was set up as shown above. A table was drawn out and the results were recorded. To improve the accuracy, compared to my preliminary results for my main wwdd ddw esdddds aydd ddba ndd kcdd dduk;

Experiment, I have decided to set up the circuit with the metre rule selotaped to the bench. This will make it easier and more precise as I will not have to keep on holding the wire then putting the crocodile clips on. I have chosen to use a meter ruler because the lengths that I will be measuring are to big for a smaller ruler and the meter ruler can be accurate to +1mm. Make sure that the metre rule is actually one metre long and not one or two centimetres shorter. Next, move the crocodile clips down five centimetres rather than ten (as done in preliminary) each time to record the results. Use the E26 wire as it will also be easier to measure any change in resistance. To collect the data for my graph I have chosen to take a range 20 of lengths.

Conclusion

This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

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