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The resistance of a wire

Extracts from this document...

Introduction

Kimberley Beattie Physics coursework The resistance of a wire Aim- To find out how the length of a wire affects its resistance. Introduction- Metal is a good conductor of electricity. This is because their atoms contain small negatively charged particles called electrons. Some of these electrons are not fully attached to their atoms. This means that they can be easily detached and made to flow through the metal. This creates a current. If a wire has a low resistance, then more current will flow through the wire easily. Before the electric current was fully understood, people thought that the current flowed from the positive to the negative. This is opposite to the flow of electrons and is now know as the conventional current. An electrical current is a flow of an electric charge, so the amount of charge is will depend on the strength of the current. This is measured in Coulomb's. The equation for this is: - Charge= Current x Time Q = I x T Coulombs= Amperes x Seconds Factors affecting resistance Thickness- There are some factors that affect the resistance of a wire. The first of these things is the thickness of the wire. A thicker wire will have less resistance than a thin wire, because there are more paths for the electrons to flow through. The easier that it is for electrons to pass through a wire, the lower its resistance is. Material- The material a wire is made from can also have an affect on the amount of Resistance it will have. Some wires may contain more atoms than other materials. This would mean that there would be an increase in the amount of collisions between the atoms and electrons. This would mean that there might be a higher resistance. Copper would have a higher resistance than ni-crome, as the ni-crome is a better conductor of electricity that copper. ...read more.

Middle

0.32 12.50 86 4 0.32 0.31 0.32 12.70 88 4 0.30 0.31 0.31 13.12 90 4 0.29 0.29 0.29 13.80 92 4 0.28 0.28 0.28 14.29 94 4 0.27 0.28 0.28 14.55 96 4 0.27 0.28 0.28 14.55 98 4 0.27 0.27 0.27 14.82 100 4 0.26 0.27 0.27 15.10 24 S.W.G Length Voltage Current (Amperes) Resistance (Cm) (Volts) Attempt 1 Attempt 2 Average (Ohms) 10 4 3.64 3.65 3.65 1.10 12 4 3.30 3.31 3.35 1.19 14 4 3.05 3.00 3.03 1.32 16 4 2.55 2.72 2.64 1.52 18 4 2.44 2.53 2.49 1.61 20 4 2.31 2.32 2.32 1.73 22 4 2.11 2.19 2.15 1.86 24 4 1.98 2.04 2.01 1.99 26 4 1.88 1.93 1.91 2.01 28 4 1.78 1.82 1.80 2.22 30 4 1.68 1.67 1.68 2.39 32 4 1.56 1.57 1.57 2.56 34 4 1.45 1.54 1.50 2.67 36 4 1.40 1.48 1.44 2.78 38 4 1.35 1.40 1.38 2.91 40 4 1.33 1.40 1.37 2.93 42 4 1.24 1.25 1.25 3.21 44 4 1.22 1.20 1.21 3.31 46 4 1.16 1.17 1.17 3.43 48 4 1.12 1.13 1.13 3.56 50 4 1.09 1.10 1.10 3.65 52 4 1.05 1.05 1.05 3.81 54 4 1.03 1.04 1.04 3.87 56 4 0.99 1.00 1.00 4.02 58 4 0.96 0.95 0.96 4.19 60 4 0.90 0.89 0.90 4.47 62 4 0.89 0.89 0.89 4.49 64 4 0.85 0.86 0.86 4.68 66 4 0.85 0.85 0.85 4.71 68 4 0.84 0.84 0.84 4.76 70 4 0.80 0.81 0.81 4.97 72 4 0.79 0.80 0.80 5.03 74 4 0.78 0.78 0.78 5.13 76 4 0.76 0.74 0.75 5.33 78 4 0.74 0.71 0.73 5.52 80 4 0.71 0.71 0.71 5.63 82 4 0.70 0.69 0.70 5.76 84 4 0.68 0.67 0.68 5.93 86 4 0.67 0.65 0.66 6.06 88 4 0.65 0.66 0.67 6.11 90 4 0.62 0.64 0.63 6.35 92 4 0.62 0.64 0.63 6.35 94 4 0.61 0.61 0.61 6.56 96 4 0.60 0.60 0.60 6.67 98 4 0.59 0.58 0.59 6.84 100 4 0.58 0.57 0.58 6.96 22 S.W.G Length Voltage Current (Amperes) ...read more.

Conclusion

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. ...read more.

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