Monochromatic light of wavelength 600 nm is incident from air on to water surface. The frequency of refracted light is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \( 5\times10^{14}\,\mathrm{Hz} \)
The frequency of light is set by the source and does not change when the light passes from one medium into another; only the speed and the wavelength change. So the frequency in water equals the frequency in air, which follows from the wavelength in air.
\( \displaystyle \nu = \frac{c}{\lambda} = \frac{3\times10^{8}\,\mathrm{m\,s^{-1}}}{600\times10^{-9}\,\mathrm{m}} = 5\times10^{14}\,\mathrm{Hz} \)
Note: NTA picked this question from an NCERT (2026-27) exercise and changed the figures. Do not ignore NCERT while practising numericals.
NCERT (2026-27):
Exercises – …
