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Physics GCSE Coursework:Factors affecting the resistance of a wire

Extracts from this document...

Introduction

Physics GCSE Coursework:

Factors affecting the resistance of a wire

Ali Hlaiyil

Introduction:

Before starting my coursework I have decided to choose 2 factors that will affect the resistance of a wire.  I will do this by going through all of the factors that affect the resistance of a wire and how I would measure each factor to find out which would be the most effective and easiest factor to measure.
Below is a list of factors and reasons why they affect the resistance of a wire. From this list of factors I will only pick 2 factors to investigate.

Resistance occurs when the electrons traveling along the wire collide with the atoms of the material of the wire. These collisions slow down the flow of electrons causing resistance. Resistance is a measure of how hard it is to move the electrons through the wire.

These are some of the factors that affect the resistance of a wire:
- Temperature: If the wire is heated up the atoms in the wire will start to vibrate because of their increase in energy. This causes more frequent collisions between the electrons and the atoms as the atoms move into the path of the electrons. This increase in collisions means that there will be an increase in resistance.

image00.png

- Material: The type of material will affect the amount of free electrons that are able to flow through the wire. The number of electrons depends on the amount of electrons in the outer energy shell of the atoms, if there are more or larger atoms then there must be more electrons available. If the material has a high number of atoms there will be a high number of electrons causing a lower resistance because of the increase in the number of electrons.

...read more.

Middle

70

0.22

0.22

0.23

1.5

1.6

1.5

60

0.22

0.2

0.22

1.3

1.1

1.2

50

0.26

0.27

0.26

1.2

1.2

1.2

40

0.28

0.29

0.28

1

1.1

1

30

0.28

0.29

0.3

0.8

0.8

0.8

20

0.32

0.32

0.31

0.56

0.6

0.5

10

0.44

0.4

0.41

0.4

0.19

0.19

After working out, here is a table showing the mean averages and resistances;

Length of wire (cm)

Averages

Resistance (ohm)

Current

Voltage

100

0.17

1.8

10.2

90

0.19

1.7

8.9

80

0.21

1.6

7.6

70

0.22

1.5

6.8

60

0.21

1.2

5.7

50

0.26

1.2

4.6

40

0.28

1

3.6

30

0.29

0.8

2.8

20

0.31

0.5

1.6

10

0.41

0.2

0.5

Conclusion:

In my prediction I said that:
”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.

This is shown in my diagrams below;

image01.png

Wire A is half the length of wire B,

therefore because wire A has 20 atoms wire B will have 40.

In this diagram the wire is half the length of the wire below and so has half the number of atoms, this means that the electrons will collide with the atoms half the amount of times.
Also if the length of the wire was trebled or quadrupled then the resistance would also treble or quadruple, and so on.

Therefore my findings and results support my prediction that the length of a wire is directly proportional to it’s resistance.

Analysis:

...read more.

Conclusion

Evaluation

The experiment went fairly well, with good results and graphs obtained all round. We didn’t encounter any problems, and as far as seen so far there were no major problems at all. Many steps could be made to make the results more accurate, and precise.

When measuring the wire lengths for the experiment, we didn’t cut fairly, and we measured out approximate lengths roughly depending on a ruler that was quite a it away. One major improvement that would affect the results a lot would be to make these readings more accurate, this is because the length/width of the wire is THE MAIN variable of the experiment, and so if this is altered even by a extremely small amount, it would make a lot of a difference to the results.

I think both the experiments were fair tests, including the preliminary test, however they could be improved if we repeated the experiment a few more times, because then we would have got a broader range of results, and they would be more accurate.

Safety was a big issue due to the fact that we were using sharp wires and a high volume of electricity, so we wore eye protection and lab coats all of the time.

If I was to repeat this test, I would make sure that I got more than 3 readings per test, so that I can get more accurate results. To improve it even more I would use a broader range of lengths and widths, especially more SWG values for the 2nd test (width as a factor).

Hopefully to go on and investigate the different factors that affect the resistance of a wire, in the near future I will be able to conduct more tests using different factors as variables, including using temperature and pressures of wires, which would make a considerable difference to the overall view of how the rate of a reaction is dependant on factors.

...read more.

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