1. The problem statement, all variables and given/known data Two waves travel next to each other for 100cm. Wave A passes through a glass container containing liquid. The thickness of the glass in total is 1cm and the width of the liquid is 10cm. The glass has n = 1.52 and the liquid has n=1.33. Wave B passes through a vacuum and has wavelength 500nm. Both waves start out in phase. Find the relative phase differences at the finishing line (after 100cm). 2. Relevant equations c/n = λv (?) 3. The attempt at a solution I'm not sure where to start. I was thinking that the phase difference will be proportional to the difference in time it takes to get to the finish line. Δφ = Δt But I have no idea how to find the difference in the time it takes for each wave to get to the end.