1. The problem statement, all variables and given/known data A triple-slit experiment consists of three narrow slits, equally spaced by distance d and illuminated by light of wavelength λ. Each slit alone produces intensity I1 on the viewing screen at distance L. Consider a point on the distant viewing screen such that the path-length difference between any two adjacent slits is λ. What is the intensity at this point? Express your answer in terms of I1 What is the intensity at a point where the path-length difference between any two adjacent slits is λ/2? Express your answer in terms of I1. 2. Relevant equations I have no idea what applies to this. 3. The attempt at a solution I have no idea how to solve this. I know that the answers are 9I for the first question and I for the second. I found it in a list of problems to know for my final exam, but i have no clue how to start.