I will also measure the thickness of the wire before every reading I take to make sure that it is always the same. I will make sure that the temperature of the wire is the same each time because as the temperature increases it causes the atoms to move around more, which creates more resistance as the moving atoms create a better barrier for the current. Results 1st Attempt Length of Wire (cm) Voltage (V) Current (Amps) Resistance (Ohms) 2nd Attempt Length of Wire (cm)
Voltage (V) Current (Amps) Resistance (Ohms) 3rd Attempt Length of Wire (cm) Voltage (V) Current (Amps) Resistance (Ohms) Average Length of Wire (cm) Voltage (V) Current (Amps) Resistance (Ohms) Analysis: In my prediction I said that: I predict that as the length of wire increases so will the resistance.
I have found that my results are actually incorrect because I havent calculated the resistance but I can analysis the affect the length of wire has on the current. These results are incorrect because the voltage shouldnt be the same each time. The voltage should be measured across the wire so as the length increases the voltage should decrease. The resistance is then found from diving the voltage by the current. I can see from my results that my prediction was right because after the current has passed through the wire it decreases.
This is more evident as the length of the wire increases because the current decreases as the wire increases. I can see from my average of results that when the length of the wire has doubled the current has almost halved because when the length of wire was 30 cm the current was 0. 65 amps and when the length of wire was 60 cm the current was 0. 32 amps, half of 0. 65 is 0. 325. I can see on my graph that my results a fairly accurate because three out of five of them touch the line of best fit and the forth point is 0. 1 amps higher than the line of best fit. My reading for 30 cm is 1. 1 amps higher than the line of best fit.
From reading the line of best fit the reading for 30 cm should be 0. 54 and I got the reading 0. 65. The reading for the 70 cm of wire that I got was 0. 26 but on my line of best fit it is 0. 25. I can also see from my results the amount at which they decrease each time the length of the wire is increased is very similar. The difference between 30 cm of wire and 40 cm is 9 amps, the difference between 40 cm and 50 cm is 7 amps, the difference between 50 cm and 60 cm is 7 amps and the difference between 60 cm and 70 cm is 6 amps. This also shows that my results were fairly accurate and reliable.
Evaluation: The first thing I would like to do is do my experiment again so that I can measure the resistance properly so that I can see if my prediction is really correct. I would measure the resistance properly by measuring the voltage across the wire and the diving the voltage by the current. I can see from my results that because all my readings do not touch the line of best fit they are not totally reliable. This may be because the temperature of the wire was different each time as I did not monitor the temperature or the length of the wire may not of been accurate because of the way the crocodile clips were placed.
I would like to improve this by using pointers instead of crocodile clips; I would do this because pointers would be more accurate. The pointers would be more accurate because the tips have a much smaller area than the crocodile clips giving a more accurate measurement of the length of wire. As well as making these modifications I would also improve my investigation by testing the same wire but different widths of wire. I would do this to expand on my investigation.