- I must now connect both of the above pieces o equipment together. When this is done, I can start collecting my results. I will start at 10 cm and increase the length of the wire 10cm each time. I will do this up to 100cm. I have decided not to increase the length of the wire over 100cm, because the results may become too small to be useful.
I have chosen to use voltmeters and ammeters to record the current and the voltage. This is because they’re simple to use and are very accurate. This will allow me to have much more accurate results.
To keep this a fair test I will:
- Use the same type of wire throughout my investigation.
- Keep the room temperature constant.
- Repeat the experiment to get more accurate results.
Predicting
The longer the wire, the higher the resistance. This is because the longer the wire, the more times the electrons within the wire will collide with each other. Therefore, more energy is going to be lost (as heat) in these collisions.
Furthermore, doubling the length of the wire will result in double the resistance. This is because by doubling the length of the wire you are also doubling the collisions that occur, therefore doubling the amount of energy lost in these collisions.
If my results show that the resistance is higher with a longer wire, then it will be obvious that my prediction is correct.
Research
Electricity is conducted through a conductor, in this case wire, by the means of electrons. The number of electrons depends on the material and the more electrons there are means a better conductor, i.e. it has less resistance. For example, copper has more electrons than iron and, as a result, is a better conductor.
The electrons are given energy and as a result move and collide with each other. This happens across the length of the wire and therefore electricity is conducted. Resistance is the result of energy lost as heat. It involves collisions between the electrons and the fixed particles of the metal. These collisions convert some of the energy that the electrons are carrying into heat.
Analysing Evidence and Drawing Conclusions
I have completed the experiment and have come up with the following results:
Results, Set 1
Results, Set 2
Looking at the tables, both of the sets of the results vary. This could be because the room temperature has changed which may slightly speed up or speed down the reaction.
Below I have put the resistance results from both tests in a table and I have worked out their combined average.
Looking at the graph I have noticed that as the length of the wire increases, so does the resistance. Up to a certain point on my graph, the resistance rises at a set level. There is an obvious error in the results that caused the change in the graph. This could have been caused by a miscalculation. It has been ruled out by my line of best fit.
My results that I have collected relate well to my prediction. I predicted correct and as the length of the wire increased, so did the resistance of the wire. This happens because the electrons within the wire collide with each other. The longer the wire, the larger chance that the particles will collide with each other. This is therefore, resistance.
Evaluating Evidence
My results aren’t totally accurate. This is because of many reasons including:
- The heat in the room could be changing.
- The results could have been misread.
There are a few anomalous results in my tables. These are shown below:
Altogether in the above results, the final reading seems to be back on its original track. This is because there was a large increase and a slow increase which seemed to even each other out.
I don’t think that the procedure that I used was suitable for the experiment. I think that it had too many problems like the results not being within the same trend. Although this was likely to be my own fault, I think it would have been more accurate if I had taken results every 5cm instead of every 10cm. This would probably have eliminated any problems with the trend of the results.
Although there are a few inaccuracies with the results, I believe that there is enough evidence collected to support a conclusion. I believe this because, up to the end results, all the previous results were all adequate. Since these results were the larger majority, I believe that there is enough evidence to form a conclusion.
I could improve my evidence of resistance by collecting results off different types of wire, both materials and sizes. I could also see if these other wires have the same trend as my wire that I have investigated.
