A long round conductor of cross-sectional area S is made of material whose resistivity depends only on

Question:

A long round conductor of cross-sectional area S is made of material whose resistivity depends only on a distance r from the axis of the conductor as p = az/r2, where a is a constant. Find:
(a) The resistance per unit length of such a conductor;
(b) The electric field strength in the conductor due to which a current I flows through it.