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# Resistance of wire

Extracts from this document...

Introduction

Ruhul Amin Choudory                Physics Coursework

The Resistance of a Nichrome Wire

PLAN

Introduction

In this investigation, I shall be investigating the resistance of wire, in terms of length. But what is resistance?

The word resistance has a vast meaning in daily-use, which means to ‘oppose’, ‘forbear’, ‘withstand’, ‘avoid’ etc. (Ms Word 2003 Thesaurus). However, the term ‘resistance’ which will be used throughout this experiment is most accurately known as electrical resistance. This is basically‘electron travelling through the wires and loads of the external circuit encounters resistance. Resistance is the hindrance to the flow of charge. For an electron, the journey from terminal to terminal is not a direct route. Rather, it is a zigzag path which results from countless collisions with fixed atoms within the conducting material’ (http://www.glenbrook.k12.il.us/gbssci/phys/Class/circuits/u9l3b.html)

The following are the factors that affect resistance:

1. Thickness/Diameter
2. Length
3. Material
4. Temperature

1) If a wire was to be thick, then obviously electrons will be able to move a little freely, but if the wire was to be thin, then electrons will move with a bit of difficulty. Since there is more space in the thick wire, therefore there is less resistance.

2) If a wire

Middle

20

6.4

0.32

30

6.27

0.43

40

5.95

0.53

50

5.79

0.62

60

5.63

0.7

70

5.45

0.76

80

5.24

0.58

 Length of wire (cm) 2nd current reading (A) 2nd P.D readings (v) 10 6.44 0.19 20 6.3 0.36 30 6.06 0.43 40 6.07 0.52 50 5.94 0.61 60 5.73 0.68 70 5.58 0.73 80 5.37 0.85

 Length of wire (cm) 3rd current reading (A) 3rd P.D readings (v) 10 6.68 0.2 20 6.5 0.3 30 6.05 0.44 40 6.07 0.54 50 5.74 0.65 60 5.59 0.72 70 5.43 0.81 80 5.08 0.87

ANALYSIS

More or less, the results seem to be quite similar to one another. As I am investigating resistance of a wire, sufficient data has been gathered to find the resistance. As noted earlier that I will be using the formula ‘V=I x R’ (voltage = current x resistance).

Using my mathematical knowledge, I will rearrange the above formula and make resistance the subject. ‘R=V/I’ (resistance = voltage / current).

Now I shall work out the resistance of all three readings.

 Length of wire (cm) Implementation of the formula answer (2.d.p) 10 0.20V/6.54A 0.03 ohms 20 0.32V/6.

Conclusion

0.002ohms/cm.

I can know easily work out the resistance, if any length (cm) was given to me. For example, if I wanted to find out the resistance of a 1000cm wire, I would multiply it by 0.002ohms, which will give 2ohms. This is more time-efficient, instead of actually investigating the resistance of 1000cm Nichrome wire.

EVALUATION

I think my investigation went correctly, achieving fine results. I say fine with little uncertainty, due to believing that my results were not 100% accurate. It can be seen on the above graph that the points do no lie exact on the ‘line of best fit’.

Throughout my investigation, I didn’t have any anomalous result. The graph above shows the points on the graph are very much close to the ‘line of best fit’, implying that there were no anomalies in my results.

If I was to do this investigation again, I would have improved and attain better results if I had used 4 decimal point, electronic ammeter and voltmeter. This would ensure that I get precise readings and probably increase the chance for my readings to lie exact on the ‘line of best fit’. If I had compared my results with a colleague of mine or repeated the investigation more, it would have proved to be more reliable.

Overall, my results were as reliable as possible and I came to the conclusion that ‘as the length of the wire increases, the resistance also increases’.

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