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Resistivity and Temperature

  • Thread starter langenase
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  • #1
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Homework Statement



I'm supposed to estimate at what temp. copper will have the same resistivity as tungsten at 20 deg. C.

Homework Equations



The only equation I think is relevant is
p=p0[1+alpha(T-T0)]


The Attempt at a Solution



I know the resistivity of both copper and tungsten at 20 degrees C. I just don't know what I should do about the resistivity, p0, at temperature, T0 since I don't know either of those quantities.
I cant cancel those variables out when I set p(tungsten)=p(copper) so I'm not sure what to do.
 
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Answers and Replies

  • #2
dynamicsolo
Homework Helper
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4

Homework Equations



The only equation I think is relevant is
p=p0[1+alpha(T-T0)]


The Attempt at a Solution



I know the resistivity of both copper and tungsten at 20 degrees C. I just don't know what I should do about the resistivity, p0, at temperature, T0 since I don't know either of those quantities.
I cant cancel those variables out when I set p(tungsten)=p(copper) so I'm not sure what to do.
T0 is whatever temperature you want to use as a reference. Since you have resistivities for these metals at 20º C., that will be your T0. You want to find the temperature at which copper has the same resistivity as tungsten at 20ºC., so which resistivity goes where in the equation you gave?

The only real issue now is: what value are you supposed to use for alpha, which is the coefficient for the rate at which resistivity changes with temperature (it would have units of ohm-m/C (or K)? Are you working from tables in a text?
 

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