1. The problem statement, all variables and given/known data Im having a bit trouble with diffraction gratings lately, with sums like this: A parallel beam of light of wavelength 450 nm falls normally on a diffraction grating which has 300 lines /mm. What is the total number of transmitted maxima? A 7 B 8 C 14 D 15 2. Relevant equations dsin∅=nλ 3. The attempt at a solution Well, my answer has no reasoning, so you might as well not read it: I took d as 3.33X10^-6, lambda as 450 X 10^-9, and ∅as 90(to be honest I don't really know why I took it as 90!) Can anyone redirect me to a good diffraction grating video/website if they know of any? I really neeed to understand how to plug in units into the formulae.