A beam of monochromatic red light with wavelength 650nm in air travels in water. What is the wavelength in water?
Does a swimmer underwater see the light as red, or a different colour?
- NCSLv 72 months agoFavorite Answer
The frequency at the boundary must remain constant; since the velocity slows in the (optically) denser medium, it must be that the wavelength shortens. So the new wavelength is
λ = 650nm / 1.33 = 489 nm ◄
Color perception is based on frequency, not wavelength; the swimmer perceives the same color -- red. ◄