The atoms take up more space so there is more chance of the electrons being caught by them; more energy is going to be lost as heat. As temperature increases so does resistance. If we increase the cross section there will be a bigger area, so more free electrons available for conduction. More free electrons means a larger current so a better conductor, meaning lower resistance. Materials should effect resistance also because different materials have different amounts of free electrons. The more free electrons means better conductor so lower resistance. Resistance of different materials will vary.
I predict that from my experiment my graph will have a straight diaganol line like this. Planning As we increase the length of the wire we will be measuring the voltage when the current is at 1amp. Using these results we will work out the resistance. We do this because we need to find out if the length of a wire effects the resistance of the wire. And from these results find out how we can reduce the resistance of the wire. When measuring we will have to be accurate and make sure that the crocodile clips on the wire are exactly in line with the right measurements.
Even 1mm can change the results dramatically. We will also have to ensure that the wire is pulled taught because if its bent up a bit its not stretched out to its full length so are measurements will be wrong and could effect the experiment. We will also make sure that the current does not go over 1-amp. Because the prelim work showed us that after this amount the test will be unfair, and it will be impossible to ensure the results are valid. Because the sellotape melts, and the wire expands and looses shape. In order to get accurate results we will do three repeats of the experiment.
Are results are more reliable then because we have three to look at so we know what the measurements should roughly be around and any major errors will stand out. Analysis From doing my experiment and looking at my results I found out that as the length of the wire increases, the resistance increases. This shows that my predictions were accurate as this is what I predicted. From looking at the graph I also notice that it is a straight diagonal line, which is how I predicted it to be. This shows it is directly proportional. As the length of the wire doubles there is double the chance that the electrons will get captured by the metal atoms.
Therefore double the resistance. Double length=double resistance 10 20 30 40 50 60 70 80 90 100 gradient = up = ? across cm Evaluation I think my experiment worked well because my results were as I predicted them to be and I did a fair test. Also there wasn’t any major errors. From looking at my graph I can see it is a straight diaganol line just as I predicted. This shows it is directly proportional. To imrove my experiment and get more accurate results I could nail or solder the wire down to the ruler. This way it is more secure than the sellotape and it cant move out of position.
Instead of using crocodile clips, as these could put a kink in the wire. I could use a knife edge or something metal to just touch the wire, as this is a conductor so still allows a current to flow through. I think I have enough results to be sure of what I wrote in my conclusion. I think this because my results prove the theory as length increases resistance increases. Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.