Question

If a red light is sent into water it does not change its color, while its wavelength changes Why?

Answer 1

1. Wavelength is the length between two identical points in the adjacent cycles of a waveform.
2. The wavelength of the light changes because when the speed of light changes, the ratio of these remains constant, which is the frequency of the light wave.
3. Colour is the direct result of the frequency of a wave, not its wavelength.

So even if the wavelength changes but the color does not change because its frequency remains unchanged.