Purpose
In this activity, students will investigate the splitting of a light beam that occurs when the beam passes through a diffraction grating. You will determine the role of wavelength and line spacing in the resulting pattern.
Discussion
When light passes through a pair of thin slits, an interference pattern reveals the wave nature of light. A diffraction grating is a film with thousands of slits. Light waves passing through a diffraction grating also produce an interference pattern. The geometry of the pattern depends on the spacing of the slits and the wavelength of the light.
Required Equipment
Light beam viewing tank (or equivalent), access to water, access to scattering agent (Mop-N-Glo™, Pine-Sol™, powdered milk, or equivalent), stirring rod, long-wavelength laser pointer (red), short-wavelength laser pointer (green), low-density diffraction grating (500±100 lines/millimeter), high-density diffraction grating (1000±100 lines/millimeter), access to adhesive tape
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Student Worksheet Teacher Notes
