# The Resistance of a lead Graphite line

A measurement of lead graphite will be measured out on a piece of a4 paper I will be measuring the length and width of the strip of graphite I will draw out, I will be using a 2B pencil to make the experiment fair, I will also be using grid paper to make the measurements more precise. I will start at having a twenty-centimetre line by one centimetre line however I will be widening the length and width of the line and I will read the ohmmeter on every centimetre of the graphite line that I move the two jockeys to measure the resistance of the carbon track using the 20k settings to measure in mega ohms.

I will take reading from every one centimetre three times in order two find the average and so to make it a fair test. I will be using jockeys in order to control the distance in which the current will flow. I will also use an ohmmeter once I have connected it to the carbon track so that I can use the results it shows and take them down. I am doing this experiment to find how variable the resistance is in the carbon track depending on length and width. The factors affecting my experiment will be the length and width so theses will be the two factors I will be placing my results on.

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Spreading electrons so the longer the carbon track or distance the more the electrons will spread causes resistance. Also the wider the carbon track the more parallel circuits that and so the spreading becomes greater. Theory Electron scattering causes electrical resistance, the longer or larger a piece of material the larger the scattering and so the larger the resistance. In creating a wider or longer carbon track is creating more parallel circuits along side each other. My prediction “As the length of the carbon track increases the resistance will also proportionally increase”

“As the width increases the resistance will then proportionally decrease” My reasons are explained in my theory I am also going to make sure throughout the experiment that when I increase the length I will not interfere with the width and I will do the same with the width. I will also try to keep the temperature and the density the same to keep the experiment the same. I will choose different lengths and widths of carbon track. I will use a 30cm ruler to measure the length of carbon track. I will use jockey’s to change the length and width 1cm at a time from the starting point.

I will do the experiment three times and take an average of all of my results and plot them in a table of results. To make this a fair test When I carry out my experiment I will make sure it is a fair one, I will try to keep the temperature of the room the same all the way through so that the carbon track stays the same temperature also. I also want to make the results I obtained the most precise results I can get. I am going to measure my carbon track several times to make sure it is precise. I will then take more than one set of results for each reading and I will find an average of all my results in turn. Procedure

I am going to use a graphite pencil to create me carbon line; the graphite is a form of carbon. I will make the line twenty centimetres by one centimetre, I will also make sure I have the line and every line from this point onwards completely covered with carbon fairly densely in order for the current to be able to flow through it well enough and also to make sure my results are accurate. I will also take the temperature every twenty minutes throughout the experiment to make sure the room temperature stays the same. Once the carbon track is thick enough and precise I will connect my jockey’s to the Ohmmeter.

I will pick one constant length and start taking my readings. Once I have all of my length readings I will then increase the width by one centimetre at a time starting by making it two centimetres. I will then take my readings for the width of the carbon track I will as before take three readings for each and find my average using excel. By doing this I will be able to observe which factors affect the resistance more. Once I have my results I will then plot them in tables and graphs and analyse them. Finally I will write a conclusion and an evaluation to summarise what I observed.