Question

what is the relation between temperature vs. conductivity? and this relation will effect when material changes?

Answer 1

i'm talking abt metals and semiconductors ....

Answer 2

with the increase in temperature, conductivity decreases..

I know the relation between temperature and resistivity in case of metals: It's \(R=R_0(1+\alpha_r\Delta\theta)\) where R is resistance at higher temperature \(R_0\) is resistance at lower temperature. \(\alpha_r\) is temperature coefficient of resistance.

In case of semi-conductors the increase in temperature supplies more energy to electrons in valence band and excites them. Hence Forbidden gap (gap between valence band and conductance band) decreases and the conductivity increases.

Answer 3

means metals and semiconductors gave different behaviour with temperature?

Answer 4

and how about very low temperature? about superconductivity?

Answer 5

yeah in metals, conductivity decreases with rise in temperature. And it is just opposite in case of semi-conductor.

At low temperature, the kinetic energy of atoms/molecules in a matter decreases and "the opposition" for the flow of current (or resistance) also decreases. And thus, the material offers very low/negligible or no resistance (but that again depends on other characteristics of material).

Answer 6

so u mean EVERY MATERIAL(no maters if its conductor or semiconductor) shows the superconducting behaviour at very low temperature?

Answer 7

I am not pretty sure when it comes to superconductors but my explanation for superconductivity is correct in case of metals.
For further info and details this one might be better. http://en.wikipedia.org/wiki/Superconductivity

Answer 8

I confirm ujjwal's first comment: metals and semiconductors behave in opposite ways.