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The effect the length of wire has on resistance.

Extracts from this document...

Introduction

The effect the length of wire has on resistance

Aim

To investigate the effect the length of wire has on resistance.

Background information

Ohm’s Law. The current in an object at constant temperature is proportional to the potential difference across its ends. The ratio of the potential difference to the current is the resistance of the object. The object must be at a constant temperature for the law to apply since a current will heat it up and this will change its resistance. image03.png

(The Usborne Illustrated Dictionary of Science, C. Stockley, C. Oxlade, J. Wertheim, Page 62)

Resistance (R).

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Middle

Thickness (SWG)

Did power pack trip? (image04.png/X)

Did wire get hot? (image04.png/X)

26

X

X

30

X

X

32

X

image04.png

From this I can tell I can use 3 volts and resistance wire that is 30SWG.

Prediction

I predict that the longer the wire the more resistance it will have as there are more atoms for the electrons to hit. image08.pngThis will create more heat making the atoms move about more increasing the resistance. Thickness of the wire will have an effect. Thin wire is created by rolling out a thicker peace there is less space between atoms for the electrons to flow through.

Safety

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Conclusion

image03.pngRepeat step 2-3 with 90, 80, 70, 60, 50, 40, 30, 20 and 10 centimetres of resistance wire.Repeat steps 2-4 another two times.

Results

image05.png

Graphimage06.pngimage02.pngimage01.png

Analysis

From the results I can see that my prediction was correct in the fact that I said: I predict that the longer the wire the more resistance it will have. The graph shows that the resistance has positive correlation to the length when kept at a constant temperature. The resistance is proportional to the length. There are some stray results that are probably caused by temperature fluctuations.

Evaluation

To improve this experiment I would use a computer to record the results. I would also use different thicknesses. This would mean I would have to use the resistivity equation:image07.png

Adam Rodwell

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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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