Question

assume medium 1 is a vaccuum. medium 2 has an index of refraction n. light travels at speed v2 and (lamda)n is the wavelength in medium 2. find the relationship between the two mediums if frequency of medium 2 = (v) / (lamda)?

Answer 1

When light passes from one medium to another, its frequency does not change, but it does its wavelength. To see why this happens, consider the figure. The waves pass by an observer at point A in medium 1 with some frequency and impact on the border between medium 1 and medium 2. The frequency at which the waves pass along to an observer at the point B in between 2 must be equal to the frequency at which spend at point A. If this were not the case, the energy would accumulate or disappear at the border. Since there is no mechanism for this is present, the frequency should be constant when a ray of light passes from one medium to another. Therefore, as the correspondence must be valid in both media, and as , is that: