The Wavelenght can change in a refraction?

[PrinceDhampir]

The Wavelenght of a wave can change when it cross to another Medium, for example when the wave pass of air to water? and what is the relation with the index of refraction of the medium?

[Fu-Kwun Hwang]

wavespeed= wavelength * frequency

Frequency is not changed when wave cross to another medium.
For light, the wave speed= (wave speed in vacuum)/(refraction index).
You should be able to calculate the wavelength, now.