Analysis

On my graph, I can see that as the length of the wire increases, the resistance in the wire increases in proportion to it. On the graph we can see that as the length of the wire increases from 20 to 55cm, the resistance in the wire increases as well. This proves that my prediction was right. A shorter wire allows electrons to move at a higher rate than in a longer wire, causing less resistance. As I showed before in my prediction, wire is very similar to the hallway. A shorter hallway allows people to go through it quickly. The same happens when the electrons go through the wire. Therefore, a longer wire allows fewer electrons to go through, which causes a higher resistance and makes it rise in proportion to the length.

However, it’s not quite proportional to the length. There was anomaly on my graph. The line didn’t go straight through the points at 20 and 40 cm. The point 20cm was quite close, but the point 40cm was almost one centimetre away from the point where I predicted it to be. There are a number of reasons, why this could happen. For example, error in the current supplied by the power pack. The amount of time which my partner and me to take a reading could also have a little effect, because while we were taking the readings the voltage was changing a little bit. The change wasn’t very significant. However, I think we could improve on this, by paying more attention while taking the readings and trying to wait till the voltmeter stops measuring and gives a perfectly correct figure. There also could be another anomaly in the experiment. Although I made sure the wire was straight when the current was going through, there was still be a chance that the wire wasn’t always perfectly straight at some points, which could cause a little difference in the results. Another possible anomaly, which could occur during the experiment was the accuracy of a contact between crocodile clips and a wire. First of all, the crocodile clips could be place 1 or 3mm closer, which could cause some change. The second is contact between the crocodile clips and the wire, which could sometimes be not as accurate as it should be. This could cause a loss of some electrons, while passing from the crocodile clips to the wire.

As I said before, on my graph I drew the line which went through all the points apart of point, when the length was 40cm. It was an anomaly, so I decided to draw a straight line without passing through this point and then, mention about this anomaly when analysing. According to what I got on my graph, I can’t say that the length was absolutely proportional to the resistance at all the points. Although the change on the graph wasn’t very significant, we could probably say that the resistance was almost proportional to the length, which proves that my prediction was right, because overall all the other changes on the graph occurred in proportion to the length. Therefore, the current passing through a wire at constant temperature is proportional to the potential difference between its ends, which proves that the Ohm’s Law is right and does relate to my experiment.

However, I still think that this anomaly could be avoided, if I had an opportunity to repeat the whole experiment again. In the beginning, when the length of the wire was 20cm, the resistance began to rise. If we use a calculator, we can find out, that as the length increased from 20 to 25cm, the resistance in the wire increased by 1.35 ohms. From 25 to 30cm, the resistance increased by 1.6 ohms. Then, it continued to rise to the point 40cm, where the resistance increased just by 1.55ohms. The resistance didn’t increase as rapidly as it did before, between the points 40 and 45cm. Then, between points 45 and 50cm, the resistance in the wire increased by the highest rate, 1.75 ohms. Then, from points 50 to 55 cm, the resistance kept increasing but not so fast, it increased by 1.3 ohms, which shows that it almost reached its peak. At this stage the resistance is very high already, so it doesn’t change. From this we can see, that the resistance doesn’t always rise so fast. Sometimes, when we change the length of the wire, there’s a big increase in the resistance, sometimes there isn’t. Calculating the difference in increase of the resistance doesn’t relate to my particular investigation very much, but it is still be appropriate.

Поиск по сайту: