1. The problem statement, all variables and given/known data A 4-slit interference pattern is created by 4 slits spaced 2μm apart. At what approximate angle θ does the intensity go to zero the first time, if the incoming light has a wavelength of 450 nm? θ1st min = 2. Relevant equations d*sinθ = m[itex]\lambda[/itex] 3. The attempt at a solution I thought this problem was as simple as using the above equation, setting dsinθ = [itex]\lambda[/itex]/2 and solving for θ. When I did, I got 6.45 degrees; but the correct answer is supposed to be 3.22 degrees. Why would the angle I got be 2x the angle I'm looking for?