Question

Why coductivity decreases of conductor upon incresing temp?

Answer 1

conductivity of any material is dependent on two things:

i. Motion of free electrons

ii. Molecular vibrations

For metals, As the temperature increases, the molecular vibrations increase (in turn decreasing the mean free path of molecules in turn decreases the flow of free electrons). thus reducing the conductivity.

In case of non metals, there are no free electrons. So, only the molecular vibrations are responsible for conduction of heat and hence for non metals the conductivity increases with increase in temperature.