How does the resistivity of
(i) conductor
(ii) semiconductor vary with temperature?
The resistivity of conductors increases with rise in temperature. As the temperature of the conductor increases, the average speed of the electrons acting as the current carriers increases. 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 t , therefore resistivity increases.
In semiconductors, resistivity decreases with rise in temperature. As the temperature increased, the numbers of free charge carriers are increased due to breaking of more and more covalent bonds. Hence, its conductivity increases and resistivity decreases with rise in temperature.