A metallic spherical shell has an inner radius `R_1 `and outer radius `R_2`. A charge Q is placed at the center of the spherical cavity. What will be the surface charge density on the inner surface ?

A metallic spherical shell has an inner radius R_1 and outer radius R_2. A charge Q is placed at the center of the spherical cavity. What will be the surface charge density on the outer surface ?

A thin metallic spherical shell contains a charge Q on its surface. A point charge q_1 , is placed at the center of the shell, and another charge q_2 is placed outside the shell. All the three charges are positive. Then the force on charge q, is

Two combining spheres A and B of radius a and b respectively are at the same potential. The ratio of the surface charge densities of A and B is ________.

The magnitude of the electric field on the surface of a sphere of redius r having a uniform surface charge density sigma is

A spherical charged conductor has sigma as the surface charge density. The electricfield on its surface is E. The radius of the sphere is doubled keeping the surface charge density unchanged. Then the electric field on the surface of the new sphere is,