Why do light spit up when passed through a diffraction grating?
The light going through a diffraction grating does NOT bend as it goes through the grating. And the different colours of light ( the different frequencies of white light ) do not bend by different amounts. The light DIFFRACTS as it passes through opening in the grating which are of a similar size to the wavelength of the light. Diffraction happens to all waves as they go though openings and is the fanning out of the waves as they get clear of the opening. The diffraction grating has many ( about 500 per mm ) opening from each of which spray fans of spreading out light. These fans of light interfere with each other and generally have the effect of canceling each other out – we should see darkness on the far side of a diffraction grating but… in certain highly specific directions all of the (say ) blue frequency fans will be in step with each other and constructively interfere forming a sharp bright blue “fringe”. Every other frequency ( red , green, yellow, etc. ) will destructively i
