rockey07
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Posted on 04-11-09 3:38 AM     Reply [Subscribe]
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I just came across one physics problem. It looks like a simple problem but i'm not getting any where near to the convising answer. The question goes as follow;


At what temperature will tungsten have a resistivity 5 times that of copper. Assume that the copper is at 20 degree centigrate.


Please somebody help me on this.


 
Posted on 04-11-09 5:55 AM     Reply [Subscribe]
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There must be more information. Is there a table of reference where you can look up resistivities and such?

There's this formula for resistance but you also need alpha (temperature coefficient of resistance) for the metal:
R = Ro [ 1 + alpha (T - To)]

Ro = Resistance of Tungsten at 20 C
Given same dimensions, R of Tungsten = 5*R of Copper at 20 C
To = 20 C
alpha = temperature coefficient of resistance of Tungsten
T =?

This is my initial thought though, given you have these values which should be in the back of most physics textbooks. I might have missed something crucial here though, I'm not sure.
Last edited: 11-Apr-09 05:55 AM

 
Posted on 04-11-09 10:30 AM     Reply [Subscribe]
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Thanks a lot "bored" you made my day. Finally its making some sens now. Thanks again :-)
 
Posted on 04-11-09 10:45 AM     Reply [Subscribe]
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Rockey bhai, get your question right first. Resistivity of a material is a constant. Resistance depends on the temperature and physical attributes of the material.
 
Posted on 04-11-09 11:31 PM     Reply [Subscribe]
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pret_atma, resistivity might be a constant, but it is only constant under certain conditions. Resistivity of a material can change with temperature, dictated in part by the material's temperature coefficient. So I don't see why you think Rockey's question is invalid.

 


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