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# An experiment to find out what factors affect the resistance of a wire

Extracts from this document...

Introduction

An experiment to find out what factors affect the resistance of a wire

## Aim

For this experiment, I will be finding to test the resistance in a circuit when the length and thickness of a wire are the variables.

## Prediction

My prediction is that the wire will produce more resistance if the wire length is increased. I predict this because the resistance will increase if the resistor in size increases because there will be more atoms for the current to flow through. This will mean that there is more resistance. I also predict that as the thickness of the wire gets thinner the resistance will increase, this is because there will be less room for the current to flow through therefore causing more resistance.

## Scientific Basis

Resistance is the change in the amount of electricity flowing through an electrical circuit. To measure the value of resistance Ohm’s Law is (Resistance = Voltage / Current) used. Four things can affect resistance:

• The material of the wire
• The temperature of the wire
• The length of the wire
• The thickness of the wire

I predicted that the resistance would increase when the length is increased because the longer the wire the more atoms the current would have to pass, causing the resistance to increase. When the wire thickness is decreased the resistance will increase because there is a smaller gap for the current to pass through.

## Equipment

The equipment I will need to use is:

• 100cm of wire, different thickness (0.71mm, 0.56mm, 0.45mm, 0.31mm and 0.28mm)
• Power Pack
• Wires
• Crocodile clips
• Voltmeter
• Ammeter
• 1m ruler
• Variable Resistor

Middle

2.35 Ω

20 cm

4.19 Ω

4.32 Ω

4.27 Ω

4.26 Ω

30 cm

6.0 Ω

6.15 Ω

6.15 Ω

6.10 Ω

40 cm

7.98 Ω

8.08 Ω

8.14 Ω

8.06 Ω

50 cm

9.83 Ω

9.87 Ω

10.07 Ω

9.92 Ω

60 cm

12.26 Ω

11.91 Ω

11.79 Ω

11.98 Ω

Tables of Results 2

Thickness: 0.71mm wire

 Change in variable resistor Voltage(V) Current(A) ResistanceResistance = Voltage / Current 0cm 0.250.260.26Average = 0.26 0.710.700.70Average = 0.70 0.37 Ω 2.5cm 0.260.260.25Average = 0.26 0.710.710.72Average = 0.71 0.37 Ω 5cm 0.270.270.27Average = 0.27 0.720.720.72Average = 0.72 0.38 Ω 7.5cm 0.280.270.28Average = 0.28 0.720.720.73Average = 0.72 0.39 Ω 10cm 0.290.290.28Average = 0.29 0.710.710.72Average = 0.71 0.41 Ω

Thickness: 0.56mm wire

 Change in variable resistor Voltage(V) Current(A) ResistanceResistance = Voltage / Current 0cm 0.260.210.24Average = 0.24 0.710.700.70Average = 0.70 0.34 Ω 2.5cm 0.260.190.25Average = 0.23 0.700.710.71Average = 0.70 0.33 Ω 5cm 0.220.200.21Average = 0.21 0.720.720.71Average = 0.72 0.29 Ω 7.5cm 0.210.220.21Average = 0.21 0.720.720.72Average = 0.72 0.29 Ω 10cm 0.220.220.23Average = 0.22 0.720.730.73Average = 0.73 0.30 Ω

Thickness: 0.45mm wire

 Change in variable resistor Voltage

Conclusion

Reliability

I believe that my results are accurate because I tested each result three times and took the average of the three. This was repeated over all of the experiments and the average resistance was also tested to give and accurate measurement.

Improvements

To improve my experiment I could make sure that the crocodile clips don’t touch any of the other wires therefore affecting the resistance reading.

Extension

To further add evidence to my experiment I could test the other two factors that affect the resistance. These are the temperature and material of a wire. This experiment would prove that each factor in the change of resistance in a circuit has a relationship with the average resistance. When the material of a wire is the variable the resistance will change because if the wire has a high density there will be more fixed particles in the wire causing high resistance, but when the wire has a low density the fixed particles will be less so there will be a lower resistance.

The temperature will make a difference because if the wire is hot there will be a lot of kinetic energy in the variable and the particles will be moving about much faster than usual and this will make the resistance higher as it is harder for the current to flow through the wire when the particles are moving around so quickly.

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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