1. The problem statement, all variables and given/known data A diffraction grating has slit width 0.83 micrometres. When light of 430 nanometres is used, diffracted beams are observed at 14 degrees 55 minutes and at 50 degrees 40 minutes to the zero order. The first beam is assumed to be the first order and the other one can be calculated to be the third order. Why is the second order missing? 2. Relevant equations d Sin (theta) = n x Lamda 3. The attempt at a solution I know that the slit width has something to do with this. Does the width of the slit cause a single slit effect which counteracts the diffraction effects for the 2nd order only but allows the first and third order to be visible?