1. The problem statement, all variables and given/known data A parallel beam of monochromatic light of wavelength 580nm is incidentally normal on a diffraction grating. The separation between successive lines on the grating is 0.7μm as shown in the figure. please refer to the photo , i am having problem with part (a) 2. Relevant equations 3. The attempt at a solution my working is d sin θ = λ sin θ = λ /d , where d is the seperation between slits.. by plug in value of λ = 580x10^-9 and d = 1/ (5000x10^2) , i have my θ = 47 ° , the ans given is 56° why am i wrong?