Express electrical conductivity in terms of charge, mass, number density and relaxation time.

Using the concept of free electrons in a conductor, derive the expression for the conductivity of a wire in terms of number density and relaxation time. Hence obtain the relation between current density and the applied electric field E.

What do you understand by electrical resistivity and give its relation in mass, charge, number density and relaxation time.

Define the term resistivity and write its S.I. unit. Derive the expression for the resistivity in terms of number density of free electrons and relaxation time.

Define the terms : Mass number

Write the mathematical relation for the resistivity of a material in terms of relaxation time, number density, mass and charge carries in it. Explain using this relation, why the resistivity of a metal increases and that of semiconductor decreases with rise in temperature.

Derive an expression for drift velocity of free electrons in a conductor in terms of relaxation time.

Explain how does resistivity of a conductor depend upon number density n of free electron relaxation time tau ?

What is electric potential enerrgy due to a system of charges? Derive an expression for it.

What is electric potential enerrgy due to a system of charges? Derive an expression for it.

Define average relaxation time. Find the expression of drift velocity in terms of average relaxation time?