A) Find the diffraction order from the grating that has an angle of incidence of 40 degrees and a diffraction angle of 20 degrees. The wavelength of incident light is 500nm and the spacing between the grooves on the grating are 5 micrometers B) If I want to selectively emit 500 nm wavelength from the grating, what is the actual range of wavelengths that would be diffracted if the grating had 6500 grooves. I was able to answer part A easily but I can figure out part B. This is for a chemistry class and I cant find any relevant formula. The only ones from the book are snells law and n(Lambda)=d(Sin(theta)+sin(Phi)) and that's no use. What is/are the relevant formula(s)?