Once these excess electrons establish a uniform distribution on the outer surface of
the sphere, there will be no net electric field within the sphere. Why not? Since
there is no additional excess charge inside the conductor, there are no excess
charges to serve as a source or sink of an electric field line cutting down into the
sphere because field lines begin or end on excess charges.
There can be no electric field within the body of a conductor.In fact, you can shield yourself from electric fields simply by surrounding yourself