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

(b) The emergent beam is white.
(c) The light inside the slab is split into different colours.

White light will split into different colours inside the glass slab because the value of refractive index is different for different wavelengths of light; thus, they suffer different deviations. But the emergent light will be white light. As the faces of the glass slide are parallel, the emerging lights of different wavelengths will reunite after refraction.