A linearly polarised electromagnetic wave given as `E=E_(0) hati " cos "(kz - omegat)` is incident normally on a perfectly reflecting infinite wall at z =a. Assuming that the material of the wall is optically inactive the reflected wave will be given as

Options

A. `E_(r) = E_(0)hati(kz - omegat)`
B. `E_(r) = E_(0)hati cos(kz + omegat)`
C. `E_(r) = -E_(0)hati cos(kz + omegat)`
D. `E_(r) = E_(0)hati sin (kz - omegat)`

Answer

B

Explanation

When a wave is reflected from denser medium, then the type of wave does not change but only its phase changes by `180^(@)` or `pi` radian.
Thus, for the reflected wave `hatz = -hatz, hati = - hati` and additional phase of `pi` in the incident wave.