Derive an expression for drift velocity of electrons in a conductor. Hence deduce ohm's law.

The drift velocity of electrons is given by

(i) Derive an expression for drift velocity of free electrons. (ii) How many drift velocity of electrons in a metallic conductor vary with increase in temperature ? Explain.

Derive the expression for drift velocity of free electron in terms of relaxation time and electric field applied across a conductor.

Write a relation between current and drift velocity of electrons in a conductor. Use this relaxation to explain how the resistance of a conductor change with the rise in temperature.