In a simple periscope, each plane mirror is fixed at 45∘ to the vertical axis. A beam of light travels horizontally towards the upper mirror.
(a) Calculate the angle of incidence at the upper mirror.
(b) Find the angle that the reflected ray makes with the mirror surface at the upper mirror.
(c) Show that after two successive reflections (one at each mirror) the emergent ray is parallel to the original incident beam.