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Investigating the factors which affect the resistance of a wire.

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Introduction

Investigating the factors which affect

the resistance of a wire

Aim:

To investigate how the length of a wire affects the current and resistance of a wire. There are many things that affect the resistance of a wire but I have only got the chance to do one of these. The one I will choose will depend on it being the most effective and on its ease to do.

Research:

Resistance is when travelling electrons in a wire collide with the atoms within the wire. The collisions of the electrons makes them move slower through the wire, which is what causes the resistance. So resistance is basically how hard it is for an electron to move through a wire. There are many factors, which affect the resistance of a wire, and they are described in the next section.

Some metals have less resistance than others. Wires are always made out of copper because copper has a low resistance and therefore it is a good conductor. The length and width of a wire also has an effect. In this investigation I will investigate how the length of a wire will affect the resistance in the circuit.

Key Variables:

Some of the variables that will be relevant to this investigation are:

- Length – the longer the wire, the longer it will take for electrons to reach the end of the wire. This is because there will be more collisions between the electrons.

...read more.

Middle

90cm

0.05

0.26

0.04

0.28

0.045

0.27

0.166666667

80cm

0.2

0.27

0.03

0.3

0.045

0.285

0.157894737

70cm

0.04

0.28

0.03

0.31

0.035

0.295

0.118644068

60cm

0.03

0.3

0.02

0.32

0.035

0.31

0.112903226

50cm

0.02

0.31

0.02

0.32

0.025

0.315

0.079365079

40cm

0.03

0.31

0.02

0.33

0.02

0.32

0.0625

30cm

0.02

0.32

0.02

0.33

0.025

0.325

0.076923077

20cm

0.01

0.33

0.01

0.33

0.02

0.33

0.060606061

10cm

0.01

0.34

0.01

0.34

0.01

0.34

0.029411765

The table above shows the results given in the preliminary experiments. The results do not range greatly, and it is difficult to comment on the results. The actual experiment will need to use a higher current to obtain bigger figures, so that it is easier for me to comment on. But, the current cannot be too big; otherwise it will burn the wire and affect the results. However, Constatan wire is better under higher currents and therefore should produce more accurate results for me to use.

Results #2: Actual Experiment –

...read more.

Conclusion

For example, as the length of the wire decreases by half, then the resistance increases by half in proportion. If the wire was to triple in length, then the resistance will decrease by triple in proportion again.

Evaluation

From my results table and graph, I can see that the results I collected were very reliable. I can tell this, because my results table does not show any individual anomalous results. This means that I did not have to leave any results out of my averages, because they were anomalous. Also, on the graph I can see that none of the averages plotted are anomalous, because all of the averages lie either on, or close to the ‘Line of Best Fit’.

But, to improve my investigation, it could have tested the resistance with a different material wire, or the same wire but at different thickness’ to see whether the resistance is greater or weaker due to there being more atoms in the same length of wire. Also, more readings could have been taken, i.e. every 5cm rather than every 10cm, so that it could me more to comment on and would be a more accurate way of testing my prediction. I could have also taken down more readings for each wire length to find a better average and in case there were some anomalous results, which would give room for error.

...read more.

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