The magnitude of the electric field just outside the surface

The magnitude of the electric field just outside the surface of a solid metal sphere centered at the origin is 2 V/m. The sphere has a 1cm radius, and is sitting in a vacuum. The magnitude of the electric field at r = 0.5 cm is: 2 V/m 0V/m 4 V/m Unknown because it is inside a solid and nobody can get in there

Solution

0 V/m is the correct answer

in vaccume, magnitude of electric field of solid metal sphere is zero. in any other medium magnitude of electric field of solid metal sphere is uniformly increases from the center with the radius