Gratings Concept

Demonstrations in Gratings

Green laser on adjustable stand with Cornell diffraction plate, producing a multiple-slit interference pattern on white paper attached to the blackboard; pattern shows a bright central spot with a few side maxima
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Multiple Slit Diffraction

A Cornell plate provides multiple-slit patterns and gratings of various densities. Students observe how increasing the number of slits sharpens the principal maxima while keeping their angular positions fixed, and …
Projected diffraction pattern in dark room: bright white zeroth-order stripe on left from projector, first-order continuous spectrum (blue through red) on right with discrete blue, green, and red laser spots visible within it
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Lasers and White Light

Compares diffraction of three individual laser wavelengths (red, green, blue) with white light from a slide projector through the same grating. Students see discrete laser spots at specific angles alongside …
Three PASCO Scientific transmission diffraction gratings in metal slide mounts, labeled 100 LINES/MM, 300 LINES/MM, and 600 LINES/MM, on a green surface
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Transmission Gratings

Demonstrates how grating line density affects angular separation of diffraction orders. Comparing 100, 300, and 600 lines/mm gratings with a laser, students directly observe that higher line density (smaller) produces …
LED tower in a dark room with all LEDs illuminated from white at top through reds, orange, yellow, greens, turquoise, blues, to violet at bottom; first-order diffraction spectra visible to the right of each LED

LED Tower

A vertical array of eleven labeled LEDs spanning the visible spectrum (400–640 nm plus white) provides a concrete reference for wavelength-color relationships. Used with a diffraction grating, students can verify …
Green laser on a lab jack with beam grazing a machinist's scale, producing a vertical column of bright diffraction spots on the wall above; a ring stand rod is visible behind the setup
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Diffraction from a Machinist's Scale

A laser beam grazes a machinist's scale at a shallow angle, and the regularly spaced rulings act as a reflection diffraction grating. Students see multiple diffraction orders and can connect …
Colorado CD mounted vertically in finger clamp on ring stand, illuminated by green laser with bright specular reflection on wall
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CD as Reflection Grating

A CD's regularly spaced tracks (~1.6 μm pitch) act as a reflection diffraction grating, producing multiple visible diffraction orders from a laser beam. Students connect microscopic periodic structure to the …
Green laser beam grazing a vinyl record on a lab jack, producing a vertical line of bright diffraction spots above the record surface
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Diffraction from a Phonograph Record

Demonstrates diffraction from a reflection grating using a vinyl record's groove structure. Students observe multiple diffraction orders and connect everyday objects to wave optics principles.
Green laser diffraction pattern from mesh showing complex multi-directional array of bright spots against dark background
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Diffraction through Mesh

Laser light through circular apertures (0.04 and 0.08 mm) and mesh screens produces Fraunhofer diffraction patterns, demonstrating light's wave nature. Students observe Airy patterns and two-dimensional grating patterns, and verify …