Question

a beam of light in air is incident at an angle of 35 degrees to the surface of a rectangular block of clear plastic (n = 1.49). the light beam first passes through the block and reemerges from the opposite side into air , calculate at what angle to the normal to that surface.

Answer 1

It'll emerge with the same angle as the angle of incidence on a rectangular slab =the angle of emergence from the same rectangular slab.                                         This is because the light ray emerges parallel to the incident ray.