A diffraction grating containing $500$ lines per $\text{mm}$ is used to study diffraction of monochromatic light of wavelength $600\,\text{nm}$. The light is made to pass through a narrow slit, and the grating is positioned so that its lines are parallel to the slit. Light then travels through the slit and on through the grating. An observer looks at the slit through the grating at different angles, moving his head from X, parallel to the grating, through Y, opposite the slit, to Z, parallel to the grating on the other side. How many images of the slit are visible to him?
Physics 9702 · AS & A Level · The diffraction grating