1. The problem statement, all variables and given/known data Light from a He-Ne laser ([itex]\lambda[/itex] = 632.8nm) strikes a pair of slits at normal incidence, forming a double-slit interference pattern on a screen located 1.50 from the slits. The figure shows the interference pattern observed on the screen What is the slit separation? 2. Relevant equations d*sin([itex]\theta[/itex]) = m*sin([itex]\lambda[/itex]) y = L*sin([itex]\theta[/itex]) 3. The attempt at a solution I know i can solve this problem if i just find sin([itex]\theta[/itex]) but this is where i'm getting stuck. Also, does the diagram tell me anything important? i thought maybe by dividing the 23mm by 4, i could get y (the distance between each bright fringe) but that proved to be fruitless when i tried solving for sinθ using 0.023/4 = 1.5sinθ but that didn't give me the correct answer for d. nevermind. i figured this out.