5.(10%) A right-hand circularly polarized wave represented by the phasor is incident normally from air onto a perfect conductor at z = 0. Find the induced current on the conducting wall.

(a) At any point (x0, y0, z0) in the domain of a scalar function V(x, y, z), we take a path ae along V= c, where c is a constant, or take a path an along ∇V. Tell me about the main characteristic(主要特徴) of these two paths a: and an, and also what is, the dot product of at and an?