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*******Physics Help***********

Original Post

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.

rockey07
Apr 11, 2009 3:38 AM · 5,316 views
4 Replies
_bored Apr 11, 2009 5:55 AM
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
rockey07 Apr 11, 2009 10:30 AM
Thanks a lot "bored" you made my day. Finally its making some sens now. Thanks again :-)
pret aatma Apr 11, 2009 10:45 AM
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.
_bored Apr 11, 2009 11:31 PM
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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