Barrier Penetration - Virtual Photon Machine



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 Code Number :  

7A50.10  

See also 6A44.42

Disclaimer:

Reprinted by permission of Dick Berg, University of Maryland, for use on this website.

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Condition :   Excellent  
Principle :   Photons at Boundaries  
Area of Study :  Modern Physics   
Equipment :   Light pipes, green laser pointer, C-clamps, Blackboard Optics, 2 - 1/2 circle lenses, glycerin or watch oil.

Procedure :   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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   References

M. K. Handy and D. F. Landegren, "A Closer Look at Optical Barrier Penetration", AJP, Vol. 45, # 6, June 1977, p. 574.

Jarbas C. Castro, "Optical Barrier Penetration - A Simple Experimental Arrangement", AJP, Vol. 43, # 1, Jan. 1975, p. 107.

"Optical Analog for Quantum-Mechanical Barrier Penetration", AJP, 33, # 5, May 1965, p.xviii.



Mail Questions and Comments to:  Dale Stille