In Example 3-5 we obtained the electric field intensity around an infinitely long line charge of a uniform charge density in a very simple manner by applying Gauss's law. Since JEJ is a function of r only, any coaxial cylinder around the infinite line charge is an equipotential surface. In practice, all conductors are of finite length. A firute line charge carrying a constant charge density pl along the axis, however, does not produce a constant potential on a concentric cylindrical surface. Given the finite line charge pl of length L in Fig., find the potential on the cylindrical surface of radius b as a function of x and plot it. Figure: A finite line charge (Hnt: Find dV at P due to charge pldx' and integrate.)