Derive expression to find the density of earth.

Derive an expression for energy density of a parallel plate capacitor.

Derive an expression for kinetic energy of rotation.

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.

Derive an expression for the coefficient of self-induction of a long solenoid.

Find the expression for escape velocity of earth.

Derive the expression for internal resistance of a cell.