Does resistance go up or down with an increase in temperature?

[Femme_physics]

I had 2 people telling me 2 different things...so I don't know the real answer. Does resistance go up or down with an increase in temperature?

 

[uart]

Yes it can go up or down. It depends on the material.

 

[Femme_physics]

Can it stay constant, too?

 

[uart]

Can it stay constant, too?

Yes, at least approximately constant. That would be called a low temperature coefficient material.

Materials in which resistance increases with temperature are referred to as having a positive temperature coefficient. Most metals are in this category.

Materials in which resistance decreases with temperature are referred to as having a negative temperature coefficient. Most semiconductors are in this category.

 

[lorenb]

In most metals, the resistance goes up with temperature. In semiconductors, the resistance actually decreases as temperature rises. I think resistivity will always change depending on temperature. But for some materials the change might be relatively small.

Actually Manganin is an alloy, which has a coefficient of resistivity of .000002. This is used for resistors because its change in resistivity due to temperature is very close to 0.

 

[gnurf]

http://en.wikipedia.org/wiki/Electrical_resistance_and_conductance#Temperature_dependence

 

[Femme_physics]

The problem with wiki is that it tends to provide more than the needed information which often confuses the reader (i.e. me)... those answers here helped me though..thanks :)