A metal ball of radius a is located at a distance 1 from an
infinite ideally conducting plane. The space around the ball is filled
with a homogeneous poorly conducting medium with resistivity p.
In the case of a <1 find:
(a) the current density at the conducting plane as a function of
distance r from the ball if the potential difference between the ball
and the plane is equal to V;
(b) the electric resistance of the medium between the ball and
the plane.