When a sound wave travel from one medium to another its frequency remains unchanged while its wavelength changes. But we know wavelength is indirectly proportional to frequency. So, how could wavelength change but not frequency?
Combining the above expression for velocity with the definition of index of refraction, we find a relationship between the wavelength l = v/f in a medium and the wavelength l 0 = c/f in vacuum:
You have rated this answer /10