1. The problem statement, all variables and given/known data A thin 1.00x10^-5 cm-thick film of MgF2 (n=1.38) is used to coat a camera lens. Are there any wavelengths in visible spectrum intensified in reflected light? 2. Relevant equations thickness = wavelength/4n (n is refraction index) ????? 3. The attempt at a solution I am guessing that the incoming light in the material reflects inside the material to cause constructive interference at certain wavelengths (which will be multiples of the thickness of the MgF2). My main question is, how do I relate possible wavelengths to thickness of the material?