1. The problem statement, all variables and given/known data A thin film of MgF2 with n = 1.38 coats a piece of glass. Constructive interference is observed for the reflection of light with wavelengths of 500 nm and 625 nm. Part A - What is the thinnest film for which this can occur? 2. Relevant equations t = lambda/2n *(m + .5) and/or lambda=(2*n*t)/(m+.5) 3. The attempt at a solution Not sure what I am supposed to do, because of the two wavelengths. I know what to do for a single wavelength... So this is my work for solving the problem with each wavelength m=0,1,2,3,... 500 = 2(1.38)(t)/(m+.5) 500(0+.5) = 2.76(t) t = 90.6 and 625(0+.5) = 2.76(t) t = 113 Now that I have done this, I am not sure how to proceed. Any help is appreciated.