Two coaxial metal cylindrical tubes, of radius a and b > a, represent a cylindrical cable. The inner conductor at a carries a linear charge λ and the outer conductor at b is grounded. Assume an arbitrary length L.
a) Determine the electric field in the region between the two conductors.
b) Determine the energy stored in the system. Recall W = ε0/2 ∫ E^2 dτ, where the integral is over all space.
c) This system also represents a cylindrical capacitor. You may recall the energy stored in a capacitor is given by W = Q^2 / (2C), where Q is the total charge and C is the capacitance. Determine the capacitance per unit length of the cable.