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To investigate the resistance of a wire.

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Introduction

To investigate the resistance of a wire

Introduction

In this experiment the factor to be investigated is the resistance of a wire in a circuit when the wire’s length is altered. This means that all other factors must stay the same or else this would not be a fair test.  I am going to investigate how different lengths of wire affect the resistance in a circuit.

I am using a voltmeter and an ammeter to measure the current in the circuit after the length of wire is changed. I am going to use five different lengths of wire and in order to make sure that this is a fair test and the results are accurate, I will repeat each experiment three times and work out the average.

The results will not be completely accurate as the length of wire may not be accurate. I also may not have put the voltage on the power box exactly on the right voltage.

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Middle

Girls with long hair should tie it back as they may knock something over with their hair.

Results

Experiment 1

Wire (cm)

Readings of Ammeter

Readings of Voltmeter

15cm

0.85

2.66

15cm

0.86

2.65

15cm

0.86

2.64

Experiment 2

Wire (cm)

Readings of Ammeter

Readings of Voltmeter

30cm

0.49

2.96

30cm

0.48

2.97

30cm

0.50

2.95

Experiment 3

Wire (cm)

Readings of Ammeter

Readings of Voltmeter

45cm

0.33

3.10

45cm

0.35

3.09

45cm

0.34

3.07

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Conclusion

Wire (cm)

Averages of Resistance (Ohms)

15cm

3.11

30cm

6.04

45cm

9.05

60cm

12.15

75cm

15.54

Conclusions

My results agree with my prediction.  When the length of wire is longer, there is more  space for the electrons to move through the wire, therefore there is a higher chance of them colliding with each other and creating resistance.  I have also seen that, through the course of the experiments, the Ammeter readings decrease, and the voltmeter readings increase.

Evaluation

My experiments all went well, except the Graph shows that the results are close to perfect apart from the last experiment. I noticed that through the course of the experiments, the Voltmeter readings seem to get higher in value and the Ammeter readings seem to decrease.

If I had more time, I would have done the experiments more times each for a fairer test. I would also use more accurate and new equipment, as the equipment I used has been used many times before and may not measure the resistance perfectly.

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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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