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Factors affecting the resistance of a wire.

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Introduction

Factors affecting the resistance of a wire Prediction I will investigate how different lengths of wire will affect the resistance. I believe that the longer the wire, the higher the resistance. This is because the longer the wire, the more nuclei stand in the way of electrons, restricting the space in which they have to move through. This causes the wire to heat and the current to go down. Electrons are not lost, but they take longer to get through the wire. I have sketched a graph to show my prediction. As you can see, as the length increases so does the resistance. Ohm's law shows that my theory is correct: Voltage (v) = current (A) x resistance ( ) Also shown in the diagram: "If you increase the resistance by making the wire gradually longe, then less current will flow if the voltage remains constant. If you increase the voltage then more current will flow." ...read more.

Middle

I then measured an 100cm long piece of nychrome wire and placed it between 2 crocodile clips 3) I turn the voltmeter and ammeter on and finally the power pack. 4) I took the readings and recorded them (see next page) 5) I rearranged the crocodile clips to form lengths of wire 90cm, 80cm etc long and repeated the experiment for each length making sure the wire was accurately measured. Results Length (cm) Volts Amps Resistance 100 4.78 0.3 16.0 90 4.77 0.33 14.5 80 4.69 0.36 13.0 70 4.60 0.40 11.5 60 4.50 0.47 9.6 50 4.39 0.54 8.2 40 4.20 0.66 6.4 30 4.00 0.80 5.0 20 3.70 1.05 3.5 10 2.80 1.74 1.7 Length (cm) Volts Amps Resistance 100 4.74 0.28 16.9 90 4.67 0.33 14.2 80 4.62 0.37 12.5 70 4.53 0.41 11.0 60 4.44 0.47 9.5 50 4.33 0.54 8.0 40 4.17 0.66 6.3 30 3.91 0.85 4.6 20 3.56 1.14 3.2 10 2.68 1.90 1.4 Length (cm) ...read more.

Conclusion

were as short as possible to make sure there was no major resistance through them. This would provide me with more accurate results and a more reliable experiment. I would also record my results in two or three decimal places to make sure that if, when rounded up and two or more numbers were the same, I would keep more decimal places and would therefore have a more accurate resistivity result. I could also increase the number of different lengths, which would then create more results giving me a more accurate graph and line of best fit. I would also allow myself more time so I can do the experiment more times and therefore have more results, so I could end up with a more accurate line of best fit. The crocodile clips I would use would be sturdier as they clipped onto the wires very loosely, making them dangerous and prone to falling off. Although using the same length of wire ensures a fair test, it could be damaged from previous circuits and lengths. ...read more.

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