Carbon in the form of a pencil Essay Example for Free

Carbon in the form of a pencil Essay Although with this line I could not prove that width and resistance of a carbon track have an inversely proportional relationship, this means that as one increases the other decreases in proportion. Although to show that this relationship applies in this case I have to plot in a graph resistance against the reciprocal of the width (which is 1 divided by the width). When I did this the graph produced a set of results which when a line of best fit was drawn it produced a straight line which passed through zero. This means that my prediction that width and resistance would be inversely proportional was true. The shape of the initial graph of width against resistance also shows simply that as the width increases the resistance decreases. The resistance also decreases far quicker for the smaller widths and as the width gets to about 5cm although it is still decreasing it is much more gradual. Evaluation: I believe that using my results I can draw useful and correct observations this is because I repeated every reading I took three times and then averaged them. I then plotted the graphs with the averaged results meaning that they are fairly reliable. Although, there are some results I feel especially on the width and resistance graphs that appear anomalous and I would have liked to repeat these readings again but due to time restraints I couldnt. In particular the resistances of the widths above 4cm appear incongruent. This may be because on the larger widths the contact did not span the entire width of the carbon track (as shown in the diagram below) although on the smaller widths, which produced the results, I had expected it did span the entire width. The results may have also been affected by the fact that the contacts remained in the same place for every reading, meaning that towards the end as the contact had a fairly sharp edge the carbon where the readings were being taken may have been rubbed off. This would mean that the resistance would be greater than expected which is the case in the later results. Therefore if was to do the experiment again and had unlimited time I would have redrawn the width line every time so that the effect of the contacts rubbing off carbon would not have an effect. This is because the contact would not have been removed from the track and so no carbon could be removed from the track. Another improvement to the experiment I would make would be improving the accuracy of the carbon track. This would mean that the carbon would be uniformly thick throughout the line and would go exactly up to the line and not pass it. This is so that we could know that the resistance was of exactly 5cm was not the resistance of between 4. 5cm and 5. 5cm. To do this I would make a template for the carbon track, which, could be coloured in ensuring that the carbon would no go past where it is, desired which happens no matter how hard you try to stay within the lines. An example of this is in the carbon track I drew, which appears to be quite good in that no carbon went over the lines but on closer inspection it in place is over a millimetre past the line. My carbon line in normal view: As you can see the line appears perfect. Magnified view of Carbon track: This closer view shows that the carbon track is by no means perfect and this degree inaccuracy means that the results may not be what they should. The patterns in my graphs were fairly obvious to find and I believe that when I did use a straight fit best line instead of a curve it was acceptable because it was more fitting for the readings. 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. Download this essay Print Save Not the one? Search for