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Lab #31.4
Light: Diffraction in Action
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
Download
Student Worksheet
Teacher Notes
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