A perfectly conductive plate is placed in the y z-plane. An electromagnetic wave with electric field is incident on the conductor. If the wave strikes the plate at t = 0, what are the directions of the electric and magnetic fields of the reflected wave immediately after reflection?

Electric field will move in y-direction, while magnetic field will move in z-direction.

Explanation:

If we make a sketch of electromagnetic wave propagation, we will discover that, the direction of the electric field will be towards y-direction and the direction of the magnetic field will be towards z-direction.

Therefore, if electromagnetic wave with electric field is incident on the conductor, immediately after reflection, Electric field will move in y-direction, while magnetic field will move in z-direction.