Question

A point charge is placed at the centre of a closed Gaussian spherical surface of radius r. Electric flux passing through the surface is φ How is the electric flux φ through the surface affected when the following changes are made in turn:

(i) The spherical surface is replaced by a cylindrical surface of the same radius?

(ii) The point charge is replaced by an electric dipole?

Justify your answer in each case.

Answer 1

(i) Since the charge inside the Gaussian surface remains the same, the electric flux through it remains unchanged.

(ii) Since the net charge inside the surface is zero, the electric flux passing through the surface also becomes zero.