Question

How does one explain increase in resistivity of a metal with increase in temperature?

Answer 1

Answer:

The resistivity of conductors increases with rise in temperature. ... This in result increases the number of collisions and the average time of collisions decreases with temperature. Since the resistivity is inversely proportional to the average time , therefore resistivity increases.

hope this helps you

Answer 2

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With increase in temperature, the relaxation time ( average time between successive collisions) decreases and hence resistivity increases

OR

In metals there are free electrons at normal temperature so when we increase temperature it resistivity gets increases,so conductivity decreases,while in semiconductor the electrons are not free so when we increase the temperature the covalent bonds begin to break and the electron becomes free so conductivity get increases.