Why wavelength of light changes while its frequancy remains the same in refraction?

Claude Bile

Nature requires that the phase of an EM wave must remain continuous across a boundary. In order for the phase to be continuous for all time the frequency must be constant.

Therefore, it is the wavelength that must change upon a change in velocity.

Claude.

Claude Bile Recognitions: Science Advisor	Why wavelength of light changes while its frequancy remains the same in refraction? Nature requires that the phase of an EM wave must remain continuous across a boundary. In order for the phase to be continuous for all time the frequency must be constant. Therefore, it is the wavelength that must change upon a change in velocity. Claude.