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# Carbon track experiment

Extracts from this document...

Introduction

Luke Johnston

Physics Coursework - Carbon Track Experiment

Aim: To investigate if the resistance of a carbon track is proportional to its length and width.

Introduction: Carbon has interesting properties and this is why I am investigating it as it is a very important element in electronics. It is a semi-conductor, which is why carbon is very interesting, which means that it behaves like an insulator when cold, but when warm it becomes poor conductors. Carbon is a form of graphite, which I will be using to investigate. Graphite is unusual because it is a non-metal which conducts and is the only non-metal pure element that conducts electricity which makes it useful in electronic circuits.

Theory:

Resistance (considered in this experiment) is the slowing of a current through the carbon track. This means that the carbon track is a conductor. A conductor is an element which allows electricity or heat through their electrons. The more free electrons elements have, the more that element can conduct.

The electricity gives the free electrons a charge and so they begin to move randomly and crash into other free electrons. This happens all along the length of the conductor and so the electrons begin to move from the negative connection to the positive connection (this happens because electrons are negatively charged). Resistance is caused by these free charged electrons crashing into fixed particles (nuclei and protons), other free electrons and particles.

Middle

Average (Ω)

1.0

3.43

3.32

2.94

3.23

3.0

6.93

7.07

7.11

7.04

5.0

10.93

12.96

10.70

11.53

7.0

12.78

17.18

17.82

15.93

9.0

15.44

20.30

21.45

19.06

11.0

18.53

24.49

22.64

21.89

13.0

22.11

26.96

26.01

25.03

15.0

27.22

29.05

29.67

28.65

17.0

30.90

32.43

33.46

32.26

19.0

34.84

37.19

34.90

35.64

21.0

37.33

39.56

38.77

38.55

 Width (cm) Test 1 (Ω) Test 2 (Ω) Test 3 (Ω) Average (Ω) 10.0 9.7 12.7 10.9 11.1 9.0 5.7 5.5 5.4 5.5 8.0 4.8 4.7 4.8 4.76 7.0 4.3 4.5 4.6 4.47 6.0 3.7 3.5 3.5 3.57 5.0 3.3 3.1 3.1 3.17 4.0 3.0 2.9 3.0 2.97 3.0 2.6 2.7 2.7 2.67 2.0 2.2 2.6 2.1 2.3 1.0 1.9 1.8 1.9 1.87

 Width (cm) 1/width (cm) Resistance (Ω) 1.0 1.000 1.87 2.0 0.500 2.30 3.0 0.333 2.67 4.0 0.250 2.97 5.0 0.200 3.17 6.0 0.167 3.57 7.0 0.143 4.47 8.0 0.125 4.76 9.0 0.111 5.50 10.0 0.100 11.10

The reciprocal of width against resistance (1/width)

Results 2

 Length (cm) Test 1 (Ω) Test 2 (Ω) Test 3 (Ω)

Conclusion

Width

Once again, results 2 shows the most resistance due to the facts mentioned in the Length section. This is closely followed by results 1 which shows that there is not much difference in resistance in the widths of results 1 and 2 which may contradict my theory a bi, of the thickness of the carbon track affecting the resistance, but still shows that this does have an affect. In other words, the thickness of the carbon track does not have as much affect on the resistance in the width, whereas it does on the length. Again, the large copper has the lowest resistance.

Reciprocal

This basically shows the same theories as in the topic of Length just discussed above. The results 2 have the highest resistance, and then followed closely by results 1, and then the lowest, by far is the large copper.

My results show that the copper hoops were the right choice as they were easier to take readings down whereas the large copper was hard to take readings as they were so small.

Evaluation

There were anomalies in my results, mainly the large copper as it was all basically an anomalous result as it was very difficult to take the right readings. To overcome this I could have lowered the reading measurement

Page

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