1. The problem statement, all variables and given/known data Hello, I have a question regarding hydrogen spectral emission. A hydrogen source is viewed with a grating spectrometer, one spectral lines occurs at 20.5 degrees in the 1st order. What angle will this line appear in 2nd order (viewed through same spectrometer) a) cannot find this angle without ruling spacing of grating b) cannot find this angle without wavelength of spectral line c) it IS possible to find this angle with the given info Please help! 2. Relevant equations d(sinθ)=mλ 3. The attempt at a solution When I think about this, do we not need the ruling spacing to find the wavelength? From there, can we not find the 2nd order angle? The problem is, there is no option for A and B. And that's assuming I'm on the right track.