Shown in the figure is a shell made of a conductor. It has inner radius a and outer radius b, and carries charge. Q at its centre is a dipole `vecp` shown in this case:

Options

A. Surface charge density on the inner surface of the shell is zero everywhere.
B. Electric field outside the shell is the same as that of a point charge at the centre of the shell.
C. Surface charge density on the inner surface is uniform and equal to `"(Q/2)"/(4pia^2)`
D. Surface charge density on the outer surface depends on `|vecP|`

Answer

B

Explanation

We know that net charge on electric dipole is zero hence charge induced on the outer surface due to dipole is zero and due to non-uniform electric field of electric dipole, charge induced on the inner surface is non-uniform. For observer outside the shell, electric field is only due to charge Q uniformly distributed on the outer surface of shell. This is equivalent to point charge placed at the center.