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Investigation about how different factors affect the resistance of a wire

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Introduction

Investigation about how different factors affect the resistance of a wire

Aim

To discover how different variables affect the resistance of a wire.

Resistance occurs when the electrons travelling along the wire in the current collide with the atoms of the wire, it is measured using the equation R = V/I.

The different variables of the wire I will change during the experiment include:

• The length
• The cross sectional area (thickness)
• The material

Predictions

I predict that the longer the wire is the more resistance there will be.  This is because the electrons in the current travelling through the wire have a greater distance to travel so more collisions could occur between the atoms of the wire and the electrons in the current.

My second prediction is that as the width of the wire is increased the resistance will decrease.  This is because the wider the wire is the more space there is for the electrons in the current to travel through the wire.  Due to this increased space there should be less collisions.

Middle

Volts

Resistance (Ohms)

10 cm

1.76

2.23

1.27

15 cm

1.44

2.70

1.88

20 cm

1.28

2.84

2.22

25 cm

1.09

2.98

2.73

30 cm

1.00

3.16

3.16

35 cm

0.94

3.22

3.43

When the width of the wire was varied

1st Set

 Width Amp Volts Resistance (Ohms) 0.57 CM 3.94 0.86 0.22 0.34 CM 2.78 1.56 0.56 0.255 CM 2.20 2.07 0.94 0.205 CM 1.30 2.92 2.25

2nd set

 Width Amp Volts Resistance (Ohms) 0.57 CM 3.93 0.85 0.25 0.34 CM 2.80 1.57 0.56 0.255 CM 2.19 2.04 0.93 0.205 CM 1.24 2.99 2.41

Conclusion

I measured the cross sectional area of the wire widths I could obtain using a micrometer for accuracy.  I also took my results twice to make sure I had made no mistakes using the micrometer.

I know that all of my results were correct as they were also taken more than once to ensure no careless mistakes were made.

I feel I could have improved my investigation by drawing graphs for my results when I changed the variables of the material and cross sectional area of the wire.  It was not possible to do this, however, through no fault of my own.  It is not worth drawing a graph if you do not have more than five results.  Because of an unfortunate lack of different wire materials and wire widths in the classroom I could not do take a wide enough range of results, so it was not worth drawing a graph. The graph I did construct to show how changing the wire length affects the resistance of the wire was done by working out an average of the two sets of results taken.

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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