1. The problem statement, all variables and given/known data A grating with 349 lines/mm is illuminated with light of wavelength 412 nm What is the angular separation between the two lines formed in order m=2? 2. Relevant equations [tex]\vartheta[/tex] = m[tex]\lambda[/tex]/d 3. The attempt at a solution I did not know how to use this equation successfully since I did not have d. I do not know what the 349 lines/mm has to do with anything, so that is obviously what I'm missing. Help!