The resistance of a wire - Sample Essay
I will then repeat this, to make sure that my results are accurate. I will take an average of my two results and write it into my table. I will then use the equation- R = V/I, to work out the resistance from the charge. Once I have done this, I will do it again for the other two wires. I will also repeat these twice, to make sure that I have accurate results. If one of my results, looks wrong, I may repeat my experiment a third time. Results- My results are below- 28 S. W. G Length Voltage Current (Amperes) Resistance (Cm) (Voltage) Attempt 1 Attempt 2 Average (Ohms)
S. W. G Length Voltage Current (Amperes) Resistance (Cm) (Volts) Attempt 1 Attempt 2 Average S. W. G Length Voltage Current (Amperes) Resistance (Cm) (Volts) Attempt 1 Attempt 2 Attempt 3 (Ohms) Conclusion- I have now completed my experiment. I have recorded my results in a table and I have drawn a graph from my results.
From my graph, I can clearly see that the thinnest wire (28 S. W. G) had the highest resistance. This is because there are lees paths for the electrons to take through the thin wire than the thick wire. This creates a lower current and therefore a higher resistance. It is the shorter a wire, the lower the resistance. This is because there is less chance of a collision happening. This is because there is less space, so lees atoms. This means that there isn’t as many successful collisions and so creates a higher current going through the wire. This then results in a lower resistance.
The reverse of this is also true. Looking at my graph, the longer the wire, the higher the resistance seemed to be. I can see this as the line on my graph goes in a steady slope upwards. This would mean that there was less current getting through, meaning that more successful collisions were taking place. When I looked at my graph, I noticed a pattern in the results. The resistance gradually increases as you go along the length of the wire. I can tell this as the line has a graduall positive increase. The 28 S. W. G wire had the largest increase in resistance as its line on the graph has the steepest gradient.
This would mean that more successful collisions are taking place. Therefore, there is less current going through the wire and that then produces a higher resistance. The 28 S. W. G wire was just over twice as thick as the 24 S. W. G wire. This is because there is a difference of 4 S. W. G between them. This has a big effect on the resistance. My results show that my original prediction was correct. The thick wire had the most current and least resistance at its shortest point. This is because it is easier for electrons to move through the wire with out too many successful collisions between them.
I think that my graph and my results allow me to come to a definite conclusion. This is because my graph looks similar and has the same similar pattern with a constant gradient as Ohms graph. I think that this shows that apart from some strange results, my experiment was fairly accurate. Evaluation- I think that the way in which I did my experiment was ok, but I did get a few odd results. I don’t think that my result for the 22 S. W. G wire were correct. This is because it does not look right on my graph. I also do not think that my result for the 22 S. W. G wire, at 98 Cm was correct.
This is because the current increases from 96Cm to 98Cm but is should decrease. The last couple of results on the 28S. W. G wire also seemed to look a bit wrong. I can tell this from my graph, as the resistance seems a little bit too high for its particular length and width. There are many reasons that may be the cause of my odd result. The temperature of the wire may not have been accurate at some points through my experiment. This could have caused the electrons to move faster or slower and would therefore change the probability of a successful collision taking place in the wire. I found it hard to measure the wire.
This may have also been the cause of some of my inaccurate results. If I was going to repeat this experiment again, then I think that a little bit more careful planning and time could have made my experiment better and would produce less inaccurate results. One thing that I found hard throughout my experiment was that I could not clip both of my wires onto the ni-crome wire at the same time. This is because if I left them on for to long, then too much current would flow through the wire at once. This would result in the wire melting, as not all of the electrons would be able to get down it at once.
This would cause the wire to try to expand and then eventually burn out and break. This made it hard to get results as I had to hold on the wire and my hand was not very steady. This caused the digits on the ammeter to continuously change. I had to take the average result that I saw on the displaying a short period of time. Thos might not have been the most accurate way of doing this experiment and may be the cause of some inaccurate results. If I wanted to do this experiment again, I think that I might try to use some kind of sliding device to move the ammeter along the ni-crome wire.
This would also help me with my problem of moving the ammeter exactly 2Cm’s each time. This meant that some times the wires might have been move either too much or too little. This would also affect my results. If in the future, I decided to repeat my experiment, then I think that I would measure every Cm rather than ever2Cm. I think that this would make my graph more accurate and it would be easier to join up. I think I might have tried to get a more accurate ammeter if I decided to repeat my experiment.
I think that this would make a big difference to the resistance as the ammeter that I was using only measured to 2d.p. This would alter my resistance and to use more than 2d/p on the resistance when the current was measured to 2d/p would result in a loss of accuracy. Looking back on my experiment again now, I think that I should have repeated it again, as if there was one inaccurate result, then when I found the average, it would even out the inaccurate ones with the accurate ones. If I had more time while doing my experiment, then I think that I would spend more time accurate planning. I found that while I was doing my experiment, the wire started to heat up slightly from the amount of current flowing through it.
This gave the atoms more energy and so caused more successful collisions between them and the electrons. This made it harder for the electrons to go through the wire. This then resulted in a smaller current flowing and therefore a larger resistance. If I had plenty of time while doing my experiment, then I would wait a few minutes between each of my measurements. This would help to ensure that the wire was kept the same through out my experiment and so the energy in which the atoms have, would be kept the same through out.
If I wanted to gain some more information about the resistance through a wire, then I think that I might repeat my experiment, but I would use a larger variety of materials and thickness. I think that this would help, so that I could see if the pattern or trend carries on for other metals. I also think that another good way of doing my experiment would be to use a longer wire than 100 Cm. I think that this would prove weather or not the gradient of the graph to show resistance, would be continues. Overall, I think that my results were fairly reliable.
I only got a few unreliable results and I can tell this, as my graph is nearly a straight line. I think that my results are as reliable as I can get them under the circumstances. I think if I had more time and more accurate equipment, then I would be able to get very precise results. 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.