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The effects on resistance with the variables of length and thickness.

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Introduction

The effects on resistance with the variables of length and thickness.

Introduction:

For my GCSE physics coursework I must investigate what effect the length and thickness of a wire has on the resistance. Possible variables are length, thickness, material, currant/voltage and temperature.  This will be done by choosing different lengths and cross-sectional areas of wire, which in turn will be connected to a functioning circuit. The current will be measured using an ammeter and the voltage measured by using a voltmeter. With this information one will be able to work out the resistance of the circuit.

Aim: I chose to do a preliminary experiment to see what materials I should use when changing the length and thickness on my final experiment.

Results for my preliminary experiment

Material

Voltage

Current

Resistance

Length 5cm

Nicrome

4

1.9

2.1

Constanton

4

3.5

1.8

Iron

4

2.0

1.2

Steel

4

4.5

0.9

Copper

4

4.6

0.86

I will be choosing Nicrome and Constanton as my wires because they both had the largest resistance, Nicrome being 2.1 and Constanton being 1.8. This means that small changes in thickness and length will correspond to larger, changes in resistance making my results easier to analyse.

Prediction for my final experiment

I expect there to be different resistances for Nicrome and Constanton.

...read more.

Middle

1.5

1.5

0.40m

3.38

3.36

1.92

1.91

1.8

1.89

1.845

0.45m

3.35

3.34

1.12

1.10

3.0

3.0

3.0

0.50m

3.40

3.41

1.03

1.02

3.3

3.3

3.3

Constanon

Length

Voltage

Current

Resistance

Average

T1

T2

T1

T2

T1

T2

0.2m

3.2

3.21

1.90

1.92

1.7

1.7

1.7+1.7/2=1.7

0.25m

3.29

3.33

1.64

1.66

2.0

2.0

2.0

0.30m

3.39

3.42

1.35

1.37

2.5

2.5

2.5

0.35m

3.50

3.50

1.20

1.20

2.9

2.9

2.9

0.40m

3.51

3.50

1.06

1.06

3.3

3.3

3.3

0.45m

3.60

3.60

0.95

0.95

3.8

3.8

3.8

0.50m

3.35

3.36

0.79

0.81

4.2

4.1

4.15

Experiment 2:

Results for different thickness for Nicrome and Constanton

Constanton

Thickness/no.

...read more.

Conclusion

I believe the method was a good and accurate one and supported both my experiments well. I have managed to achieve good, reliable results as I worked out an average for both experiments and drew a line of best fit for both graphs. I also believe my results were good enough to support a firm conclusion as they also agreed with my prediction and scientific knowledge.

For further work relevant to this experiment we could investigate the effect of other variables such as the voltage and temperature of the wire and its effect on resistance. This would help us have a better understanding of how resistance varies under different conditions.

 To further improve this investigation I would use digital ammeters and voltmeters, to achieve a much more accurate method of measurement. It would also be a good idea to take a wider range of readings so that one can have a much more accurate average to work with.

        I have enjoyed doing this investigation and has taught me a lot more knowledge on resistance and its factors.

By Zahid Siddique 10E

...read more.

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