Okay so I've got a question. If we allow a monochromatic light, say the color green to pass from air to water, what color would the refracted light be? This thought came to me because I was reading that light, when passed through an optically denser medium, would travel slower. Since the frequency of light remains constant on refraction, speed should be proportional to wavelength. So wavelength decreases as a consequence. Should the light be green or a different color?