Question

A charge Q is distributed over a metal sphere of radius R.What is the electric field and potential at the centre?

Answer 1

electric field inside a metallic sphere is zero
and potential V=kQ/R

Answer 2

charges have nature to reside the outer surface of a conductor, so electric field inside the conductor becomes zero. and potential inside the conductor remains constant and that is, equal to potential at the surface of conductor.

here in question, A charge Q is distributed over a metal sphere (a conductor). charge distributed over the outer surface of metal sphere due to this electric field inside the metal sphere , E = 0

potential inside the metal sphere = potential at the surface of metal sphere

= KQ/R

hence, potential at the centre of metal sphere is KQ/R.