7A50.10 - Frustrated Total Internal Reflection - Barrier Penetration - Virtual Photon Machine

Code Number:
Demo Title:
Frustrated Total Internal Reflection - Barrier Penetration - Virtual Photon Machine
Photons at Boundaries
Area of Study:
Modern Physics
Light Pipes, Green Laser Pointer, C-Clamps, Blackboard Optics, 2 - 1/2 Circle Lenses, and Glycerin or Watch Oil.

See also 6A44.42 in Optics.

The object of the experiment is to show that there are virtual photons at a boundary layer, such as the edge of the light pipes or the straight edge of one of the 1/2 circle lenses.

Press the light pipes together with a C-clamp where the light beam bounces off the edge in one and the beam will be directed into the other pipe.  Or point the laser into one of the lenses when it is set at an angle and show the total internal reflection.  Smear a little glycerin or watch oil onto the flat edge of the other lens.  Bring this lens up to the other lens to form a full circle and the laser ray will jump the boundary layers of the two lenses and become a straight line.  You can also use glycerin with the light pipes if you want to dispense with the C-clamps.  Since we are using very crude optics and methods this is obviously not a perfect demonstration but it will still get the point across in a dramatic fashion.

NOTE: The watch oil that we have is fairly old and as it breaks down has a fairly unpleasant odor.  Glycerin is more environmentally friendly.

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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.