What is the resistivity of nichrome? Watch

minnie
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#1
Report Thread starter 12 years ago
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Hi,

I have done an experiment using a nichrome wire and found that its resistivity is 1.22 x 10-6. Can this be right? I did my experiment with normal conditions, the room was probably slightly above room temperature. When I look at other values for the resistivity of nichrome it is supposed to be 1.1 x 10-6 . Is it right that my value is that different from this numberor have I done something wrong?

Cheers for any help.
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Eau
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Report 12 years ago
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It's supposed to be 110 × 10-8 ohm.meters

Source: http://www.8886.co.uk/ref/resistivity_values.htm

But according to you, the real value and experimental values are so close, that it's amazingly close for an experiment. No worries, allow for experimental error, e.g. uneven width of wire etc.
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Morbo
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Report 12 years ago
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Something that immediately springs to mind is whether you took into account the resistance of any other connecting wires you used.

Also, when you start passing current through the wire (if that's what you were doing), its temperature increases, which increases the resistivity.

Other things might be that you did not take enough readings, or drew a graph a bit wonky.

Would need more info on the method before I could provide any more help...

EDIT: In response to your post, Wildfire, 110x10-8 is 1.1x10-6! And on the contrary, a 10% experimental error is not acceptable. Something is wrong. If she used a micrometer, then this is not the source of a 10% error, and she should have taken 5 or 6 readings of diameter along the length of the wire and averaged them. Maybe some equipment was not calibrated properly, or it's a different composition to 'standard' nichrome which we're getting these values for. There are many things that could be the problem.
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DARTHCHESS
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Report 8 years ago
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Hey all, yeah, I just did a similar experiment, I got 109 x 10^-8 using normal crappy school equipment, it is possible to attain good readings!
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Stonebridge
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Report 8 years ago
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(Original post by minnie)
Hi,

I have done an experiment using a nichrome wire and found that its resistivity is 1.22 x 10-6. Can this be right? I did my experiment with normal conditions, the room was probably slightly above room temperature. When I look at other values for the resistivity of nichrome it is supposed to be 1.1 x 10-6 . Is it right that my value is that different from this numberor have I done something wrong?

Cheers for any help.
The whole point of working out experimental errors when you do an experiment like this, is to be able to say whether the result you get lies within or outside that margin. Until you give a value for your estimated error, you can't say whether or not your result is "right" or "wrong".
A 10% error in a school lab experiment isn't unusual, though it would be better if it were lower.
Did you plot a graph of V against I for the wire to measure its resistance? That reduces the final experimental error. You can use the graph to estimate the uncertainty in that final result by drawing best and worst gradients.
What was the uncertainty in the voltage and current measurements?
As another poster stated, did you take an average value of the diameter of the wire?
Over to you...
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