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Resistance of a Wire

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Introduction

"Resistance of a Wire SC1" PLAN With a given energy source, such as a battery, the size of current that flows is decided by the resistance of the circuit. All conductors resist the flow of electric charge to some extent, but some are better than others. The bigger the resistance of a conductor the harder it is for electric charge to flow through it. That is the definition of resistance. For my Physics coursework, I will be investigating the factors that affect the Resistance of a circuit. There are many factors, which could affect the resistance of a circuit and below are these factors: � Temperature - This affects the investigation because the hotter the metal the harder it is for the electrons to get through, the cooler the metal then the easier it is for the electrons to pass through. This is because the hotter particles are vibrating more than the cold particle making the electron work faster to get through this is illustrated below. When Cool When Hot � Length of Conductor - the length of the conductor will affect the investigation because the longer the wire the more difficult it is for the electrons to pass as the longer the wire the more energy the electrons have to use. ...read more.

Middle

I will also be carrying out some preliminary work to see which voltage is the best to use and at what distance I should start the readings. We will keep the voltage at 0.4 because if it was any higher the needle would go off the scale and the power supply would keep cutting out because the voltage was to high and the trip blown. Also for my preliminary work I constructed a circuit like that shown in Fig 1a only I replaced the test piece with a light bulb. I changed the volts but kept everying else the same and these are my results: Potental Difference (Volts) Current Flow (Amps) Resistance (Ohms) 1 0.15 6.67 2 0.14 14.29 3 0.18 16.67 4 0.20 20 5 0.21 23.81 6 0.22 27.27 7 0.24 29.17 8 0.26 30.77 9 0.29 31.03 10 0.30 33.34 This is what the graph looks like: From this graph I can see that the greater the potential difference, the more the resistance levels off, if it obeyed ohms law then it would be a staight line graph. TABLE OF RESULTS These are the results from the final experiment: Length (Cm) Current Flow (Amps) Resistance (Ohms) Increase Length Decrease Length Average 10 4.60 4.50 4.55 0.09 20 2.20 2.20 2.20 0.18 30 1.50 1.60 1.55 0.26 40 1.20 1.30 1.25 ...read more.

Conclusion

From this I can draw the conclusion that the length of wire does affect the rate of resistance because when you double the lenghth of wire the resistance goes up but current flow goes down! EVALUATION I feeel that my groups experiment went well, there were no real problems were took our time and measured as accuratly as we could, making our result satisfactory. We had some anomolous results, which could be down to many things like: � The Crocodile clips not put on straight instead they could have been placed on the wonk as show below, this could mean that the distances inbetween the clips was incorrect � We could have read the instruments incorrectly. � The crocodie clips could have been slightly rusty � There could have been some Parallax error, where we did not read the instruments straight on. I think that if I was to do the experiment again then I would be even more careful with the crocodile clips, I could also use electronic gauges to give me more accurate results and the other main thing would be to not rush as much because the second experiment was slightly rushed because we ran out of time. Overall I am pleased with my effort and am happy that I have supported my theory that when you double the length of the wire the resistance goes up and the current flow halves. ...read more.

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