Question

When the light passes through the achromatic combination of prisms, then what is observed
A. Only deviation
B. Only dispersion
C. deviation and dispersion
D. None of the above

Answer 1

Hint: To answer this question first we must have a concept of what is achromatic combination. And we know achromatic combination is that combination in which the two lenses are of different nature and of different focal lengths. Achromatic lenses are those which are free from chromatic aberrations.

Complete answer:
When white light goes through a prism, it splits into seven distinct bands. When two prisms are joined in such a way that the total of the angular dispersions of the crown and flint glass prisms is zero, the result is an achromatic prism combination. When the white light passes through the combination of achromatic prism, the internally scattered components of white light from the crown glass prism refract and then meet at the outer surface edge of the flint glass prism, transforming the refracted light back into white light with deviation and without any dispersion.

Hence, the correct option is A.

Note: In optics, a prism is a clear piece of glass or other transparent material with precise angles and plane faces that can be used to analyse and reflect light. A simple triangular prism can separate white light into its component colours, which is known as a spectrum.