# Angle of Refraction

A light beam passes from medium 1 to medium 2 with the latter being a thick slab of material whose index of refraction is n2. Show that the emerging beam is parallel to incident beam.

Am I correct in assuming that the only way this is possible is to have the incident beam making an angle that is 90 degrees with medium 2? Can someone confirm my thinking.

$$\mu sinx=k$$ where k is a constant, so for sinx1=sinx2, n1=n2. Since n1 & n2 arent the same, the only angle for which the equality holds is 0, which means that the ray falls normally on surface 2.