Question

A narrow beam of white light goes through slab having parallel faces.Then:

• A. the light never splits in different colours.
• B. the emergent beam is white.
• C. the light inside the slab is split into different colours.
• D. the light inside the slab is white.

Answer 1

Answer: (B), (C)

The correct options are
B the emergent beam is white.
C the light inside the slab is split into different colours.

Due to dispersion , light at the violet end of the spectrum exhibits a larger angle of refraction on entering the glass than light at the red end . This causes splitting of all colours inside the slab . All the colours of light return to their original direction of propagation as they refract back out into the air . As a result , the outgoing beam is white .