An infinite, uniform line charge with linear charge density λ = +5 µC/m is placed along the symmetry axis (z-axis) of an infinite, thick conducting cylindrical shell of inner radius a = 3 cm and outer radius b = 4 cm. The cylindrical shell has zero net charge.
The electrical potential is chosen to be zero at the outer surface of the cylindrical shell, V(b) = 0. (In this problem, it is not possible to chose the potential to be zero at infinity because the charge distribution extends to infinity.)
(c) Calculate the potential at a radial distance r = a/2.
Vp-Vref = -∫E•dl = 2kλ*ln(Rref/R)
The Attempt at a Solution
Since the point b = 0.4 is the reference point I substituted that into the equation. Here is what I did:
R = 0.03/2 = 0.015
V = 2*(8.99x10^9)*(5x10^-6)*ln(0.04/0.015) = 88176.54985V
What did I miss?