Question

A beam of light composed of red and green rays is incident obliquely at a point on the face of a rectangular glass slab. When coming out on the opposite parallel face, the red and green rays emerge from

• A. two points propagating in two different non-parallel directions
• B. two points propagating in two different parallel directions
• C. one point propagating in two different directions
• D. one point propagating in the same direction

Answer 1

Answer: (B)

two points propagating in two different parallel directions

Answer 2

In any medium other than air or vacuum, the velocities of different colours are different. Therefore, both red and green colours are refracted at different angles of refractions. Hence, after emerging from glass slab through opposite parallel face, they appear at two different points and move in the two different parallel directions.