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Q & A: Copper vs. Nichrome

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Most recent answer: 10/22/2007
Q:
which one permits less current copper or nichrome? why?
- Anonymous
A:
I think what you mean is: if you put the same voltage on a wire of each material, which one let's more current through? The voltage is the "push" on the electrons, and their flow is the current. If you have a nichrome wire and a copper wire the same size and shape, with the same voltage on them, much more current will flow through the copper. We say that the copper has higher 'conductivity'
or lower 'resistivity'.

The biggest single reason why it's harder for the current to flow through the nichrome is that it's an alloy of two metals, nickel and chromium, which are not too similar to each other. Instead of
flowing smoothly through the material, the electrons frequently bounce off the unevenness that the mixed-up nickel and chromium atoms make.

You can picture this by thinking of waves travelling in a shallow pond. If the bottom is even, the wave will travel smoothly. If the bottom is lumpy, the wave will scatter off in different directions. It sounds like I'm saying something weird- that to understand how electrons move in a wire you have to think of them as waves. That really is what I'm saying!

There are other things too that make nickel and chromium happen to have more resistivity than copper, even if the nickel and chromium are separate. But those things also involve thinking about the electrons as waves, and I've probably said enough weird stuff for
today.

Mike

(published on 10/22/2007)

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