Code Number: 6C10.20

Demo Title: Diffraction - Fingers and Squinting

Condition: Good

Principle: Diffraction of Waves

Area of Study: Optics, Astronomy

Equipment:

A distant or pinpoint light source, your fingers.

Procedure:

Look at a distant light source through a gap in your fingers that are just far enough apart to see through. You should see a diffraction pattern that changes as you increase or decrease your finger gap.

References:

Robert Ehrlich, "Q.9, Squinting at an Unfrosted Bulb", Turning the World Inside Out, p. 201.
Borislaw Bilash II, David Maiullo, "Two-Finger Diffraction", A Demo a Day: A Year of Physics Demonstrations, p. 350.

Disclaimer

These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist. The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose. The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources. Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks. These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage. Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.

Instructional Resources and Lecture Demonstrations

6C10.20 - Diffraction - Fingers and Squinting

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