6A44.57 - Submerged Light Bulbs

Code Number:
6A44.57
Demo Title:
Submerged Light Bulbs
Condition:
Good
Principle:
Lenses and Image Formation
Area of Study:
Optics
Equipment:
Frosted light bulbs or radiometers.
Procedure:

Place the frosted bulbs into a tank of water.  The glass envelope will appear to thicken and the frosted coating will appear to shrink as the bulb is submerged.

A glass radiometer can be substituted for the frosted light bulb.

References:
  • James E. Kettler, "Some Optical Effects Using a Hollow Sphere and an Aquarium", TPT, Vol. 22, #3, Mar. 1984, p. 171.
  • Van E. Neie, "Optical Effects in a Neutral Buoyancy Simulator", TPT, Vol. 19, #1, Jan. 1981, p. 53, also A Potpourri of Physics Teaching Ideas - Optics and Waves, p. 211.
  • Richard Breslow, "Optics in a Fish Tank", TPT, Vol. 14, #4, Apr. 1976, p. 234, also A Potpourri of Physics Teaching Ideas - Opics and Waves, p. 209.
  • Mark C. James, "Novel Optical Properties of a Submerged Light Bulb", AJP, Vol. 76, #9, Sept. 2008, p. 856.
  • Doug Johnson, "Future Index of Refraction Demo", Tap-L discussions, Sept. 24, 2008.

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.