Investigating the Resistance of Wire.

     Based on this information, I can now make a prediction. I predict that the longer the wire, the higher resistance will be. This is because the longer the wire, the further the electrons have to travel, and the longer the wire, the more collisions there will be between the electrons in the wire and the wire atoms. This means energy would be given off as heat, increasing resistance. This is based on our preliminary work on how the thickness of wire affects resistance.

Using our procedure of connecting the circuit, collecting relevant data and then repeating the process, we collected the relevant evidence: Current and voltage (also with the length of wire), from which we could work out resistance of the wire. To work out resistance, we used the formula R = V/ I . This means Resistance equals voltage divided by current.  The results are shown below:

Test 1:

Test 2:

Test 3:

From this we worked out the average resistance of each length of wire (by adding all the resistance values for that length of wire and dividing by three):

These results can now be plotted on a graph:

From these tables and charts we can see a correlation. It is a positive correlation, meaning that as the length of wire increases so does the resistance. The correlation also appears to be directly proportional from X to Y, which means that there is an equal rate of increase in resistance. An example of this would 30 and 60 cm: the resistance in 30cm is 1.50 ohms, and through 60cm of wire there is exactly 3.00 ohms. This is directly proportional, since when the wire is doubled the resistance is too. The theory behind electricity and conduction supports this too: The longer the wire, the more atoms there are, The more atoms mean more collisions with electrons, so there is less flowing through, which makes for a higher resistance. An example of this would be if a 10cm wire had 8000 atoms, a 20cm length of that wire would have 16,000. If there were 800 collisions in the 10cm length of wire, there would be 1,600 in the 20cm length. This conclusion supports and proves my prediction fully, as we can see from the graphs and results.

     Mostly the experiment was a success. We collected reliable data easily and quickly, without any problems. We had preliminary work to back up our data, conducted repeats and made sure it was a fair test. The evidence we have is good quality, was directly proportional to a good quality extent, but wasn’t totally accurate (most resistance values are a small amount of an ohm off direct proportion). The main anomaly appears to be the metre value, since the resistance is quite far under direct proportion. It is .11 under what it should be for 1M, and so are a few other values, this could be down to a battery not fully charged; it isn’t too inaccurate though. Our procedure was good too, but more repeats could have been done to make sure it was a fair test. On the other hand, more repeats could have made the data less accurate due to almost all the results being slightly inaccurate. The evidence we have collected is sufficient to support our theory, and although we do have one large anomaly and a few small ones, we also have a few perfect examples of direct proportion. To provide extra evidence, more repeats could have been done, and an extra experiment on different types of wires, seeing how the material affects resistance. Overall it was a good and accurate experiment.