Question

The wavelength of light diminishes n times ( n= 1.33 for water) in a medium.A driver from inside water looks at an object whose natural colour is green .He sees the object as
(1) green
(2) blue
(3) yellow
(4) red

Answer 1

Colour of light is determined by its frequency and as frequency does not change, colour will also not change and will remains green.
If the color of the light was dependent upon its wavelength, then its color would change when it enters a medium with a different index of refraction. But it does not.

Answer: (1) green.