The figure below shows a portion of an infinitely long, concentric cable in cross section. The inner conductor has a linear charge density of λ = 6.10 nC/m and the outer conductor has no net charge.
(a) Find the electric field for all values of R, where R is the perpendicular distance from the common axis of the cylindrical system. (Use R as necessary.)
1.50 cm R 4.50 cm
R 6.50 cm
(b) What are the surface charge densities on the inside and the outside surfaces of the outer conductor?
∫EdA = Qinside/ɛo
The Attempt at a Solution
Using the above equation I would get E(2pi*r^2*h) = Qenclosed/ɛo, but it is infinite in length and therefore no height is given. Any help appreciated.