Question

An achromatic combination of lenses produces :

• A. image in black and white
• B. coloured images
• C. image unaffected by variation of refractive index with wavelength
• D. highly enlarged images

Answer 1

Answer: (C)

image unaffected by variation of refractive index with wavelength

A proper combination of a convex and a concave lens may result in no change in focal length of the lens system for different lights. It is known as achromatic combination of lenses. So, in this combination image is unaffected by variation of refractive index with wave length.