Electrons move more easily through some conductors than others. The opposition of a conductor to current is called its resistance. A good conductor has low resistance and a poor conductor has high resistance. These electrons are free to move within the material conducting them as excess electrons, which is why electrons flow through metal in a circuit. A material with high resistance would make it hard for the electrons to pass through. Therefore when electricity flows it is because there is a range of materials with free electrons in the circuit.
I believe that a thicker piece of wire will have less resistance because there is more space for the electrons to flow through. Also, as nichrome is commonly used in electric resistance and heating elements I am confident that current will easily flow through the wire. I used information from previous class work and the following websites to draw up, my hypothesis:
pages/nichrome
Results:
24 s.w.g. (0.57 mm)
26 s.w.g. (0.46mm)
28 s.w.g. (0.37mm)
Looking at my table of results and my graph I can see that the thicker pieces of wire have less resistance. I have come to this conclusion by looking at my graph and realising that at 50cm a 24 s.w.g. wire has a resistance of 2.17 yet a 28 s.w.g. wire has a resistance of 5.69, a significant difference. This trend continues along the lines of best fit. The reason for this difference in resistance is that normally a long piece wire has more resistance than a short thick one of the same material but as these pieces of wire were the same lengths yet various thickness, more electrons were able to pass through the thickest nichrome wire.
My hypothesis was proved accurate by this experiment and the results have successfully supported my prediction. Using scientific knowledge of resistance and current and the extra research I was able to estimate the outcome of this investigation effectively.
The method I used for this investigation was extremely reliable because it was easy to ensure that it was a fair test, as I simply needed to change the wire. I also had to ascertain that the current remained the same, so I always adjusted the rheostat so that a constant current of 0.83 was flowing before I took a resistance reading.
The evidence this investigation gave me is quite accurate as there ate no drastic anomalies. All the figures fit in with the line of best fit and the resistance of the wire increases with a steady gradient. The difference between the thicknesses of a 24 s.w.g. piece of wire and a 26 s.w.g piece of wire is 11mm and the difference between a 26 s.w.g. and 28 s.w.g. is 7mm. Due to this the gradients of the three lines on the graph compared to each other are unequal.
I think that I do have enough evidence to draw a conclusion as I have carried out the experiment with three wires with different thickness. I chose to use three different thicknesses because if you use only two and something went wrong with one there would only be one set of data to compare it to. With three pieces of wire it is unlikely that there will be a problem with all three experiments and then if there was an anomaly you would be able to discard it and still have two sets of reliable data left. Fortunately, I encountered no problems with this investigation.
I could improve my method by carrying out this experiment with other thicknesses, as that would give me more data to compare and to draw a conclusion from. I could also repeat the experiment several times in an attempt to achieve even more accurate results. A final suggestion would be to undergo this experiment with different types of metal for example, nickel or cobalt, as they are both good conductors. If I did all of these things I would be able to draw an even more accurate, useful and reliable conclusion of what factors effect the resistance of a piece of wire.
