1. The problem statement, all variables and given/known data When a monochromatic light of wavelength 600 nm is viewed 2 m away through a diffraction grating, two similar lamps are observed, one on each side of it, and each 0.30 m away from it. Calculate the number of lines in the grating 2. Relevant equations sinθ = (n*λ)/d 3. The attempt at a solution I don't even know how to sketch the diagram ! From what i understand d=0.3 m but we don't know n !