1. The problem statement, all variables and given/known data A single slit is illuminated with 660 nm and the resulting diffraction pattern is viewed on a screen 2.3 m away. a. If the linear distance between the 1st and 2nd dark fringes of the pattern is 12 cm. What is the width of the slit? 2. Relevant equations W(X/L) = m(lambda) 3. The attempt at a solution W(.012m/.0023m = 1(660x 10^-9) W = 1.27 x 10^-7 Someone else tells me thats wrong and that I have to divide the linear distance by two to get 6 cm instead of 12. Is this true? And if so why? I really don't understand why we would have to do that.