Hi Everbody, I am having a bit of trouble with an AS Physics question regarding diffraction gratings. I have managed to solve the problem that I have been facing, although I am not completely sure that I got to it through the correct means, and also why the answer is such. 1. The problem statement, all variables and given/known data “1. Blue and red light with wavelengths 450nm and 650nm respectively, is inident normally on a diffraction grating which has 4.0 * 105 lines per meter b) Calculate the angle between the second-order maxima for these wavelengths.” 2. Relevant equations nλ = d sin θ n=2 λ = 6.5 * 10-6 and 4.0 * 10-6 d=1/2.5*10-6 3. The attempt at a solution I attempted the solution two different ways with the first, and to me most intuitive method, failing. 1. sin-1 (2*4.5*10-6)/(2.5*10-6) =θ θ=21.1° This was incorrect. However, the following corresponded to the answer at the back of the book. sin-1 (4.5*10-6)/(2.5*10-6) =θ θ=10.37° Now the answer at the back of the book was 10.2°, but I assume that it isn’t the result of sheer chance. Thank you very much for your time.