Thin Films Concept

Demonstrations in Thin Films

Newton's rings apparatus viewed through the lens, showing small concentric colored interference fringes in the upper-right area of the circular field
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Newton's Rings

Projects circular interference fringes formed by the air wedge between a plano-convex lens and a flat glass plate. Students observe that the central spot is dark (due to the phase …
Projected soap film showing colorful interference bands of magenta, green, cyan, yellow, and blue swirling across the film against a dark background

Interference in a Soap Film

Students observe thin film interference as colored bands form in a soap film and evolve over time. The projected image shows how constructive and destructive interference between reflections from the …
Four views of a spinning soap film in a black cup under white light, showing evolution from small concentric rainbow rings at center, to expanded blue central region, to blue-purple field, to large gold and magenta interference pattern
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Spinning Soap Film

Demonstrates thin-film interference in a rotating soap film. Centrifugal force creates a parabolic thickness profile, producing concentric colored rings that evolve as the film thins. Students observe the connection between …
Projected interference pattern showing concentric green and purple rings on a dark background, with a bright horizontal line from the mercury lamp slit across the center
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Pohl's Plate

Light from a mercury lamp reflects off both surfaces of a thin mica sheet, creating two coherent virtual sources that produce circular interference fringes on a distant screen. Students observe …