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The resistance of a wire.

Extracts from this document...

Introduction

Prediction
I predict that if the length increases then the resistance will also increase in proportion to the length. I
think this because the longer the wire the more atoms and so the more likely the electrons are going to
collide with the atoms. So if the length is doubled the resistance should also double. This is because if
the length is doubled the number of atoms will also double resulting in twice the number of
collisions slowing the electrons down and increasing the resistance. My graph should show that the
length is proportional to the resistance.
The diagrams below show my prediction and should explain it more clearly:
  Conclusion
In my prediction I said that :
¡§¡K.if the length increases than the resistance will also increase in proportion to the length.¡¨
From my graph I have shown that my prediction was correct, as the Line of Best Fit is a straight line proving that the resistance of the wire is proportional to the length of the wire.
The length of the wire affects the resistance of the wire because the number of atoms in the wire increases or decreases as the length of the wire increases or decreases in proportion.

The resistance of a wire depends on the number of collisions the electrons have with the atoms of the material , so if there is a larger number of atoms there will be a larger number of collisions which will increase the resistance of the wire. If a length of a wire contains a certain number of atoms when that length is increased the number of atoms will also increase.

Conclusion
The way I got my results were fair, I controlled temperature, voltage, length of wire, and the resistance in the circuit.

...read more.

Middle

1

1.70

0.42

4.0

0.3

2

2.50

0.65

3.8

3.93

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3

3.30

0.83

4.0

1

1.75

0.32

5.5

0.4

2

2.60

0.49

5.3

5.40

3

3.50

0.65

5.4

1

1.80

0.28

6.4

0.5

2

2.70

0.40

6.8

6.63

3

3.60

0.54

6.7

1

1.85

0.23

8.0

0.6

2

2.75

0.35

7.9

7.93

3

3.65

0.46

7.9

1

1.90

0.19

10.0

0.7

2

2.80

0.30

9.3

9.60

3

3.70

0.39

9.5

1

1.90

0.18

10.6

0.8

2

2.85

0.27

10.6

10.60

3

3.80

0.36

10.6

1

1.90

0.16

11.9

0.9

2

2.80

0.24

11.7

11.73

3

3.70

0.32

11.6

1

1.90

0.14

13.6

2.0

2

2.80

0.21

13.3

13.27

3

3.75

0.29

12.9


Graph


Conclusion

I conclude that the longer the wire, the higher the resistance. This is because in a longer wire, there are more wire particles. Resistance is caused by electrons colliding with wire particles. Where there are more particles electrons are obviously more likely to have collisions, leading to a higher resistance

In a longer circuit, it is more of a struggle for electrons to get around the circuit without any collisions. There are lots more particles to avoid. Less electrons were able to get past at any one time in the wire, meaning that less current showed up on the ammeter. This means higher resistance.

The wire with the highest resistance was the longest one – 1m long. This had a mean average resistance of 13.27Ω. This was as expected in my prediction. I said that the longer the wire the higher the resistance, and this was the case. Also, the wire with the lowest resistance was the 0.1m one. This had a resistance of 1.3Ω. The reason for this is that there are not so many particles in a short wire. This means that there were fewer collisions between the electrons and the wire particles. A low resistance translates as not many collisions, and therefore lower resistance.

Metals conduct electricity due to a large amount of “loose” or “free” electrons in their atoms. These free electrons can carry electricity easily. When there is no electric field in a wire the electrons stay still, but as soon as you put an electric field there the electrons will move from the negative to the positive. I have illustrated this below.

You could compare resistance to a high street.

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Conclusion

Conclusion

In my prediction I said that resistance is directly proportional to length, and I have proven this to be correct, by following by plan and a well worked out method that is both fair and accurate. The length of the wire affects the resistance of the wire because the number of atoms in the wire increases or decreases as the length of the wire increases or decreases in proportion. The resistance of a wire depends on the number of collisions the electrons have with the atoms of the material, so if there is a larger number of atoms there will be a larger number of collisions, which will increase the resistance of the wire. If a length of a wire contains a certain number of atoms when that length is increased the number of atoms will also increase. From my results table and graph I can see that my results that I collected are very reliable. I know this because my results table does not show any individual anomalous results this means that I did not have to leave any results out of my averages because they were anomalous. Also on the graph I can see that none of the averages plotted are anomalous because all the averages lie along the same straight line.

Evaluation

If I were to make any changes to my experiment I would have put the voltmeter apparatus on the wire that was being tested. By using this way it would of measured the voltage of that wire, instead of the wore that was being tested and the rest of the circuit.

Also I would of tested the same wire, as I had done in the experiment described above, but used different thickness of the wire, to see how this affected the resistance to add to my investigation.

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