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To investigate how the length of a wire affects its resistance.

Extracts from this document...

Introduction

Resistance of a Wire

Investigation

Aim

To investigate how the length of a wire affects its resistance.

Introduction

Electricity flows through some things better than others. How well something conducts electricity is measured by its resistance. Resistance in a wire depends on how thick the wire is, how long it is and what it's made of. The lower the resistance of a wire, the better it conducts.

There are many other factors that affect how much resistance an object has. The factor that I will be investigating will be the length of wire, and how this affects the amount of resistance the wire has.

Background Knowledge

The knowledge that I already have on this topic is on Ohms law and how to measure resistance using a voltmeter and an ammeter.

Ohm's law says that the amount of current flowing in a circuit is directly proportional to the electromotive force put on the circuit. This means that if you double the number of batteries in a circuit, the current flowing through the circuit will also double. Similarly, Ohm’s law states that the current flowing through a circuit is inversely proportional to the total resistance of the circuit. This means that if I double the current in a circuit, the resistance will drop by double the amount. Using Ohm’s law I can work out the resistance when I know the current and voltage.

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Middle

1.52

2.04

1.64

2.04

1.62

20

2.60

1.04

2.84

1.12

2.79

1.13

30

2.98

0.81

3.21

0.84

3.19

0.86

40

3.70

0.64

3.46

0.69

3.52

0.68

50

3.71

0.57

3.64

0.58

3.06

0.59

60

3.72

0.50

3.75

0.50

3.77

0.50

70

3.86

0.43

3.87

0.45

3.88

0.49

80

3.94

0.39

3.99

0.40

3.96

0.40

90

4.04

0.36

4.08

0.36

4.00

0.36

100

4.10

0.33

4.09

0.33

4.11

0.33

My results show that the higher the voltage, the lower the current and I believe that this true for all of the results. Because I have compared my data with three experiments I believe that all of the data is accurate – though, the 50cm experiment on the third test is slightly out of place. This can be put down to a unique error in the reading of the result or a sudden fault in the voltmeter. However, the most probable cause of this irregular result is the change in the surrounding temperature. Temperature affects the resistance because if the wire is heated up, the atoms in the wire will start to vibrate more rapidly. This will cause more collisions between the electrons and the atoms due to atoms moving into the path of the flowing electrons.

Now, I will find the resistance for each test as I have the voltage and current. After working out the resistance I will find the average of the resistances. Taking the average is a more accurate method of measurement of a wide range of readings.

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Conclusion

As well as making these modifications, I could also expand on my investigation by testing the same wire but different widths of that wire. I think the circuit and method used was suitable as it was very time efficient to work with. However, if I had time, I would do the experiment again but changing the separate lengths of wire each time.

...read more.

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