A cable is made from two coaxial cylindrical shells. The outer shell has radius b and charge per unit length λ, and carries a longitudinal current I. The inner cylinder has radius a < b and charge per unit length − λ, and carries the current I back in the opposite direction.

(a) Integrate the Poynting vector to find the rate at which energy flows through a cross section of the cable.
(b) Show that a resistor R connected between the cylinders dissipates the power calculated in (a).

Transcribed Image Text:

/R 1 → 2 -^ ... Z