E is zero, v is non zero.
Bro Gauss Law.
E zero is a consequence of Gauss law.
The field inside any conducting surface is zero, as chatge is always present on the surface.
Field, being zero, potential is calculated as in case of hollow sphere, and its value is same as that on centre.
Not center, surface. The potential anywhere inside a hollow sphere equals the potential at the surface of that sphere.