- Level: AS and A Level
- Subject: Science
- Word count: 2530
Finding the Resistivity of a Wire
Extracts from this document...
Introduction
PLANNING | |||||||||||||||||||||||||||||||||||||
Finding the Resistivity of a Wire | |||||||||||||||||||||||||||||||||||||
This is the circuit diagram for the practical part of my investigation.
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First I will cut a strip of the Nichrome wire approximately 1.20 m long and measure its diameter using the micrometer six times: at three evenly spaced points on the wire, rotating the micrometer by 90° to ensure that the diameter is the same throughout the wire and roughly cylindrical. Next I will fix the wire to the ruler. I will start by tightly fixing one end of the wire to one end of the ruler using sticky tape. Then I will ensure the wire is straight and tight before fixing it at a point approximately 0.35m down the ruler. I will repeat this at 0.65m and at the end of the metre ruler. Subsequently, I will connect the circuit as shown in the diagram, with the wire connected between 1.00m and 0.00m. Then I will begin to take measurements. I will turn on the power; adjust the supply from the power pack so the ammeter reads 0.50A. I will note down the reading on the voltmeter and then turn off the power. I will repeat this two more times with the wire at this length, turning off the power between each reading. Once the readings at this length are complete, I will turn off the power and alter the wire so that it is connected between 0.00m and 0.90m. I will then follow the same steps to take reading at this length. I will continue to do this until all 0.10m intervals between 1.00m and 0.10m are complete. |
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To prevent the wire from getting too hot, thus being a burn hazard, I will keep the current constant at a relatively low value of 0.50A. I will also turn off the equipment when I am not taking measurements. |
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Finding the Resistivity of a Wire | ||||||||||||||||
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Middle
0.01)Repeat 1
Repeat 2
Repeat 3
Repeat 1
Repeat 2
Repeat 3
1.000
0.50
0.51
0.50
0.88
0.90
0.88
0.900
0.50
0.50
0.50
0.79
0.80
0.79
0.800
0.50
0.50
0.50
0.71
0.71
0.71
0.700
0.50
0.50
0.50
0.63
0.63
0.62
0.600
0.50
0.50
0.50
0.54
0.54
0.54
0.500
0.50
0.50
0.50
0.45
0.45
0.45
0.400
0.50
0.50
0.50
0.36
0.36
0.36
0.300
0.50
0.50
0.50
0.27
0.27
0.27
0.200
0.50
0.50
0.50
0.19
0.18
0.19
0.100
0.50
0.50
0.50
0.12
0.13
0.13
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During the practical part of the investigation, I took several steps to minimise errors:
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Conclusion
I believe that my conclusion is reliable due to the quality of the line of best fit. It is a straight line that passes through zero, which is the type of line that I expected. All the points pass very close to the line, with only one slightly anomalous result. Furthermore, the gradient of my line gave me a value of resistivity close to that which I expected.
I think there is very little I could do to improve the practical set-up for my investigation. I could possibly have used a variable resistor to be more accurate in taking voltage and current measurements, but my results were accurate enough.
To further improve the reliability of my investigation, I could look at Nichrome wire of varying diameter, to see if they had a consistent value for resistivity. To do this, I would use the same set-up for the investigation, but take measurements using about five wires of different diameters. I could use the same calculations for resistivity for each wire. To continue the investigation, I could compare Nichrome wire with other materials, such as Constantan.
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This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.
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