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?

1 Answer

  • NCS
    Lv 7
    1 month ago
    Favourite 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. ◄

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