inside a spherical shell........d field is zero but not potential...
thts d best example
if electric field is zero then is it necessary that potential is zero
never
just remember
E=-dV/dr
the electric potential may or may not be zero!!!!!!!!!!!
nothing could be definitely said!!!!!!!!!
Think of a charge at the centre of a square....all force counter balance each other...
but potential not zero...
inside a spherical shell........d field is zero but not potential...
thts d best example