[SOLVED] Optics - Diffraction Hi. I was given an extra credit problem in class to derive equations related to multiple slit diffraction. I was wondering if someone wouldn't mind looking over what I have so far, and pointing me in the next direction. Thank you! 1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution For (a), I'm mostly worried about how to take into account the sum in the integral. I just sort of made up a way that I thought made sense. Having a sum and an integral in the same equation just feels strangely redundant. And, also for the second part of (b), I'm not sure how to go about the justification that it asks for. Thank you again!