1. A ray of light is incident onto the interface between material 1 and material 2. There is a figure, which is a standard figure of a ray in medium of n1 striking an interface where medium2 (with n2) meets medium1. As is typical, some of the light is reflected and some is refracted. The question asks: Given the indices of refraction n1 and n2 of material 1 and material 2, respectively, rank these scenarios on the basis of the phase shift in the refracted ray. And then goes on to list different scenarios (e.g n1=1.33, n2=1.46 vs n1=1.33 n2=1.0). The second part is the same, but asks to rank based on the phase shift in the REFLECTED ray. 2. This question is a lot different from standard ray optics questions, and I wonder why there is any phase shift at all, unless the refracted ray meets another interface where it can reflect/refract and thenTHAT reflected ray would have a phase shift from the first refracted ray, because it has traveled a different distance through medium 2. But how can you compare the phase shifts of two different refracted rays? I feel like I am missing something. Any suggestions? Thanks.