The figure below shows, in cross-section, a cylindrical metal rod surrounded by a con- centric cylindrical metal shell. The rod and shell are perpendicular to the page. The ra- dius of the rod is c. The inner radius of the shell is b, and the outer radius of the shell is a. The current through the rod is in = 2i and the current through the shell is bout = -i. That is, the currents are in opposite direc- tions, but the rod carries twice the magnitude of current. a iout iin 8 O