1. The problem statement, all variables and given/known data With regard to Young’s Experiment, derive a general expression for the shift in the vertical position of the mth maximum as a result of placing a thin parallel sheet of glass of index n and thickness d directly over one of the slits. Identify your assumptions. 2. Relevant equations 3. The attempt at a solution Sorry if this is very simple, I am having a brain fart or sorts. I've found the number of wavelengths that will travel though a plane of thickness d: N = dn/lamda_0 and with that tried to form a triangle to find the difference, delta y, however the answer's units don't make sense. I know this should be of a similar form to delta y = a/s * lambda Thanks for the help.