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Does the length of a wire affect the resistance? -- A* - page 4
Keywords: Physics length of wire resistance
By georgie1 on 31/12/2009
Level: GCSE Key Stage 4 (Years 10-11)
Page Number: 4 of 6 pages: 1 2 3 4 5 6there will be more nuclei for the electrons to flow against in a longer length of wire, increasing the resistance of the wire.
I believe that the resistance across the wire is very close to being directly proportional to the length of the wire. I can see that when the length of the wire is doubled, the resistance across the wire is increased by almost double, and that when the length is tripled, the resistance is increased by almost triple. For example:
Length/m Resistance (V/I)/ohms Ω
0.20 0.087
0.40 0.156
0.60 0.204
Although the results are not exactly and absolutely directly proportional, we can make educated predictions for other lengths by using the data that we have, and by using an approximate direct proportionality rule:
Resistance/ohms α Length/m
Upon studying my graph I can see that the error bars are of consistent range and usually fall upon the line of best fit. This shows that my results are normally reliable and my average results are vey accurate. However, for my measurements of wire length 0.60 metres, it is apparent that neither the highest, lowest or average values fall upon the line of best fit. This shows me that an additional factor has not been fairly controlled when completing the experiment (such as an increase in temperature resulting in a lower resistance).
Evaluation
Data Collection
I collected three different sets of results to obtain an average fourth set of results. When collecting my second set of results, I recorded an anomaly at 0.70 metres, and consequently repeated this measurement so that I had a more accurate and reliable average. The replacement measurement did not provide a drastically different result to the anomalous result. However, the anomalous result did not follow the consistent pattern of the other lengths, yet when I repeated it, the replacement result did. This causes me to believe that an added factor affected the wire, such as temperature. All three sets of my results then provided similar resistances for each length, making me confident that the other affecting variables were controlled and that the measurements were gathered to a suitable degree of accuracy [resistance recorded to 3 decimal places]. These results gave me enough depth to draw a sensible and likely conclusion. However, if I had collected more than ten or so sets of results, I could have calculated the standard deviation of each length of wire to see how spread out my data was and therefore the averages would be
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