Soap Filem Interference, 6D30.20

Topic and Concept:

• Thin Film Interference, 6D30. Thin Films

Location:

• Cabinet: Optics (OP)

• Bay: (B4)

• Shelf: #1

Abstract:

Glycerin film in circular wire frame, oriented vertically, is illuminated by white light. The thickness of the glycerin varies in the vertical direction due to the action of gravity (thinner at top, thicker at bottom). Thin-film interference causes horizontal bands of color to appear.

Setup and Procedure:

1. If demonstration hasn't been used in a while, water may have evaporated, leaving glycerin too thick to make a film. Dilute with tap water if necessary.
2. Set up demonstration on table so that open side of box faces white board; turn on white board lights. You should see pretty horizontal bands of color.
3. Set up table top camera at same height above table as film, and project camera view onto screen.

Cautions, Warnings, or Safety Concerns:

Discussion:

Discuss the physics behind the demonstration, explaining some of the various steps of the demonstration when appropriate.

Videos:

• Lecture Demonstration's Youtube Channel

References:

• List any references

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