1. The problem statement, all variables and given/known data The figure shows a portion of an infinitely long, concentric cable in cross section. The inner conductor carries a charge of 6 nC/m and the outer conductor is uncharged. (part 5 of 6) What is the surface charge density inside the hollow cylinder? Answer in units of nC/m^2. Knowns: Central solid conducting cylinder of radius 0.013 m and charge 6 nC/m. Inner radius of cylindrical shell = 0.0475 m Outer radius of cylindrical shell = 0.067 m Charge of shell = 0 nC/m Qenc = Q1 + Qin 2. Relevant equations (sigma) = Q/A A=2(pi)rL Flux = EA = Qenc/E0 3. The attempt at a solution I constructed a Gaussian Cylinder between the outer and inner parts of the shell. I know that E inside the shell is zero (since it is a conductor), so Qenc/E0 = 0, which means Qenc = 0. However, Qenc = Q1 + Qin, where Qin is the charge on the inside surface of the shell. The charge density (sigma) relies on Qin, and (sigma) = Qin/A However, A = 2(pi)rL, and L is not given; rather, L is infinite! I know r = 0.0475 m. Help!