Results
1.
Wire length (cm) Volts Amperes Ohms (to 2 decimal places)
10 0.77 1.12 0.69
20 0.95 0.66 1.44
30 1.08 0.50 2.16
40 1.15 0.42 2.74
50 1.22 0.35 3.49
60 1.25 0.30 4.16
70 1.29 0.27 4.70
80 1.32 0.24 5.50
90 1.35 0.22 6.14
100 1.36 0.20 6.80
2.
Wire length (cm) Volts Amperes Ohms (to 2 decimal places)
10 0.76 1.08 0.70
20 0.89 0.59 1.51
30 0.93 0.45 2.07
40 1.05 0.38 2.76
50 1.12 0.33 3.39
60 1.18 0.29 4.07
70 1.23 0.26 4.73
80 1.25 0.23 5.43
90 1.27 0.21 6.05
100 1.31 0.19 6.89
3.
Wire length (cm) Volts Amperes Ohms (to 2 decimal places)
10 0.77 1.08 0.71
20 0.94 0.69 1.36
30 1.08 0.54 2.00
40 1.16 0.42 2.76
50 1.22 0.36 3.38
60 1.27 0.31 4.10
70 1.28 0.27 4.74
80 1.31 0.24 5.46
90 1.33 0.22 6.05
100 1.36 0.20 6.80
From these results, I can see, that my original hypothesis was correct, because as the length of wire got longer, the volts reading increased, the amps reading decreased, and therefore the resistance in ohms increased. This supports my original prediction, because when the wire length got longer, there was a longer length of rigid ions for the moving electrons to use up energy getting through, and therefore the current (shown by the ammeter reading) decreased. For example in my 3rd experiment, when the length of wire increased from 10cm to 20cm, the current dropped by 0.39 amps.
These results are very consistent, and similar to each other in proportionality, as the gradient of the line of best fit for the length/ohms graph is 0.6, for the 3 sets of results.
Conclusion
After looking at the results from my 3 sets of experiments, I conclude that my original hypothesis was correct – the longer a length of wire, the more resistance it has. This also fits in with my scientific explanation in my prediction because as the length of wire and the ohms reading are directly proportional i.e. if the length of wire doubles, the resistance doubles, this suggests that the electrons are losing energy all the time they are travelling through the wires, because if they have to travel twice as far, they lose twice as much energy. This also follows ohms law because the resistance is calculated by dividing volts by amps, and as the volts reading increased, the amps reading decreased, which meant the ohms reading increased, as predicted.
Evaluation
I think that my experiment went very well. I got the results that I expected from my prediction, so I obviously got my prediction and experimental procedure right. I think these results are very accurate, because I didn’t have any anomalous data, and all the results were very similar. I can come to a firm conclusion with this data, because I repeated the experiment a further 2 times, and all the results were all similar with each set of results lying close to the line of best fit, all with similar gradients.
My experiment was likely to be slightly unreliable, because as the experiment progressed, the wire heated up, and may have affected the resistance. To overcome this problem, measurements should be taken quickly, and the wire allowed to cool down between readings. Also the length of the wire used in the experiment may not be exact, as I used a wooden metre rule, and measured it by hand, which my have been slightly inaccurate, however repeating the experiment twice should have evened out any inaccuracies.
To improve this experiment and make it more reliable, I could record results at smaller intervals of length of wire e.g. record results after every 1cm of wire instead of every 10cm. In any further experiments, I would also do a set of results with a thicker piece of wire, to see if I would get the same pattern of results, and gradient.
