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resistivity if a nichrome wire

Extracts from this document...

Introduction

Aim: Throughout this experiment I aim to find out the resistivity of a nichrome wire. To do this I will measure the resistance of the nichrome wire at different lengths and from this I will be able to work out the resistance using the equation: Apparatus Apparatus Range Accuracy Purpose Quantity Nichrome wire N/A N/A This is the wire that I will be calculating the resistivity for. It's the subject of the investigation. 1 Power pack 2V-12V � 1 V The power pack is used, as it's a supply of the initial voltage. It also creates a potential difference in order for the flow of electrons to occur (current to flow). 1 Crocodile clips n/a N/A I will be using these to hold them to the nichrome wire and to the voltmeter. I will use two to connect the wire to the voltmeter and the other end attached to 0m on the wire. The other two will be used to move along the different length on the wire, from 0.100m to 1.00m. 4 Micro screw Gauge 0-25mm � 0.01mm This will help me measure the diameter of the nichrome wire. For this I can then be able to work out the cross sectional area of the wire by using the following equation: ?r2 1 Ruler stick 0m-1m � 0.001m This is to measure the different length of the nichrome wire. 1 Wires N/A N/A They are connectors in the circuit. They connect the wire to the power supply, the ammeter and to the voltmeter. 4 Ammeter 0-10 A � 0.01 A This is used to measure the flow of electric current in a circuit. 1 Voltmeter 0-20 V � 0.01 V This instrument is used to measure the potential difference between two points in the circuit. Hence, the voltage across the wire. 1 Nails N/A N/A I will use these to hold the nichrome wire to the meter stick. ...read more.

Middle

To overcome this problem I allowed the wire to cool down, by allowing 30 second intervals between each reading, as it allowed the wire to return back to room temperature, and minimising the amount of heat in the wire. - Kinks: The thickness of the wire differed along the wire. The wire may was therefore not uniformly thick. This caused a change in the cross sectional area of the wire. To overcome this problem, I used an plier to even out the thickness of the wire Implementation Table of results I have taken the average by simply adding all the 3 voltage readings together and dividing them by 3. For example the fist reading (0.100m) was done as follows: 0.39 + 0.36 + 0.37 3 = 0.37 volts Working out the resistance. I used the equation V= IR to work out the resistance at each length. I rearranged this equation to R = V/I. The voltage value I used was the average voltage as it's the most reliable. For the first length: 0.37 / 0.24 = 1.54 Length (m) V1 (Volts) V2 (Volts) V3 (Volts) Average voltage (Volts) Current (Amps) Resistance (ohms) R=V/I 0.100 0.39 0.36 0.37 0.37 0.24 1.54 0.200 0.75 0.74 0.76 0.75 0.24 3.13 0.300 1.23 1.22 1.25 1.23 0.24 5.13 0.400 1.63 1.59 1.57 1.59 0.24 6.63 0.500 2.00 1.96 2.04 2.00 0.24 8.33 0.600 2.34 2.32 2.33 2.33 0.24 9.71 0.700 2.68 2.72 2.74 2.71 0.24 11.2 0.800 3.12 3.11 3.11 3.11 0.24 12.9 0.900 3.50 3.51 3.52 3.51 0.24 14.6 1.00 3.94 3.93 3.91 3.92 0.24 16.3 (A table to show the voltmeter readings, their average ammeter readings) Diameter of the wire Length Diameter 1 (m) Average (m) 0.200 0.3 x 10-3 0.3 x 10-3 0.500 0.3 x 10-3 0.800 0.3 x 10-3 I plotted a graph with length against the resistance. This is because it will help me to work out the resistivity. ...read more.

Conclusion

This can be caused my many sources of errors in my investigation. However, the results were close together for each repeat, this suggests that they were precise and were accurate enough and the method used was appropriate. There were no anomalous results in my readings this therefore suggests that the experiment was carried out with precision, and that the method used was appropriate. It allowed me to tabulate the results on an understandable table which could then be analysed. Improvements I believe that the technique I used to find out the resistivity of the nichrome wire was not the best as I could have went through another set of procedures and methods that would have aided me to find out the resisitvity more acutely. There were many limitations in the method which caused this investigation not to be 100% accurate. If I was to do this investigation another time, I would have made many changes to the method and even the technique used to find out the resistivity of the nichrome wire. - Data loggers/ computer software - I would have used data loggers as they would calculate the cross sectional area of the wire accurately and also would have given me an accurately plotted graph. It would also have worked out the gradient and therefore the resistance. - Ohm meter - this devise would directly measure the resistivity without any long calculations. - Different equipment - I would change the equipment used, such as the screw gauge and used electronic ones that would display readings digitally. This would decrease any systematic errors in the calculations. Throughout my experiment there were no significant errors. All my readings had a positive correlation and there were no significant anomalous results. My graph showed length of the wire being directly proportional to the resistance in the wire, with no discrepancies in the points plotted. This suggests that my investigation was carried out with precision, and that my method was appropriate. ?? ?? ?? ?? Resistivity of Nichrome Wire Candidate number: Centre number: Page 1 of 13 Fatima Osman 12.1 Dr Pithia ...read more.

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