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To investigate the resistance of a wire

Extracts from this document...

Introduction

To investigate the resistance of a wire.

Introduction

What is resistance?

Electricity is conducted through a conductor, in this case a wire, by means of free electrons. The number of free electrons depends on the material and more free electrons means a better conductor, i.e. it has less resistance. For example, gold has more free electrons than iron and, as a result, it is a better conductor. The free electrons are given energy and as a result move and collide with other free electrons. This happens across the length of the wire and then electricity is conducted. Resistance is the result of energy loss as heat. It involves collisions between the free electrons and the fixed particles of the metal, other free electrons and impurities. These collisions convert some of the energy that the free electrons are carrying into heat.

How is it measured?

The resistance of a length of wire is calculated by measuring the current present in the circuit (in series)

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Middle

Voltage

(V)

Resistance

(R)

(Ohms)

0

10

20

30

40

50

60

70

80

90

100

Obtaining Evidence

I have not made any changes to my planned method as everything ran smoothly during my experiment. However, due to time wasted in setting up equipment and putting it away again, I had to perform my experiment over a 2 day period in order to obtain a full set of reliable results. I kept all the variables constant apart from the length of the wire so as it would be a fair test.

Results

Length

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Conclusion

The results were slightly less accurate; nevertheless, they were accurate enough to produce a good directly proportional straight line graph. I think performing my experiment 3 times helped find more accurate results as I found out the average of the resistance of the wires at each length. Inaccuracy in the results may have been due to the fact that the equipment used may not have been working properly. Also, when measuring the length of wire to be tested, it is possible that I may have slightly misread the length on the ruler by a couple of millimetres because of kinks and twists in the wire making it nearly impossible to get a perfectly straight piece of wire.

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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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