Question

A narrow beam of white light goes through a slab having parallel faces

• 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 light inside the slab is split into different colours
C the emergent beam is white

Refraction of light of different wavelength is shown in the figure.The light inside slab clearly splits up into different colors. The emergent ray from a single white ray is a beam of different colors, parallel to the incident ray. However the emergent beam is white, because the white rays adjacent to the incident white ray above also split into different colors that add up to these wavelengths to produce a white beam of light parallel to the incident white beam.