A hollow metal cylinder has inner radius a, outer radius b, length L, and conductivity . The

A hollow metal cylinder has inner radius a, outer radius b, length L, and conductivity σ. The current I is radially outward from the inner surface to the outer surface.
a. Find an expression for the electric field strength inside the metal as a function of the radius r from the cylinder’s axis.
b. Evaluate the electric field strength at the inner and outer surfaces of an iron cylinder if a = 1.0 cm, b = 2.5 cm, L = 10 cm, and I = 25 A.