Refraction - Twinkling Planets and Stars

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 Code Number :   6A40.47

Disclaimer:

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

The demonstrations contained and referenced herein are listed for the purposes of cataloging and describing physics demonstrations which should be conducted only under the direction of a trained instructional support professional or physicist. These demonstrations are not presented for the purpose of being conducted by persons unconnected to this Facility and/or persons not consulting with or being supervised by the recognized instructional support professional or physicist and his/her staff. The University is responsible only for those demonstrations carried out using its own equipment using established safety and scheduling policies, and bears no responsibility for those choosing to use this source material for their own purposes. All demonstrations described and contained herein are public domain, and can also be found in reference materials in libraries, bookstores, and electronic sources.

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Condition :   Excellent   
Principle :   Change of Refractive Index with Temperature 
Area of Study :  Optics  
Equipment :   Laser, hot plate or grill lighter, screen.
Procedure :   Shine the laser on a distant wall or screen.  Place a hot plate or the grill lighter directly under the beam and close to the laser.  The image of the spot on the wall will be be steady until heat is applied after which it will appear to move, shimmer, and twinkle.  This is due to the change in refractive index of the air through which the beam moves.  The same effect takes place when viewing stars through the atmosphere.
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   References

C.L. Enloe et al.,  "Laser Deflection Through a Spark,"  Am. J. Phys., 400, Vol. 58, No. 4, (April 1990).

 

O-225:  "Star Twinkle with Hot Plate,"  DICK and RAE Physics Demo Notebook.

0-226: "Laser Dance Across Hot Plate", DICK and RAE Physics Demo Notebook.

 

"Twinkling of Stars,"  PIRA News, Vol. 9, No. 3, p. 22.

Janice VanCleave's Astronomy for Every Kid, "73, Twinkling Star", p. 158.

Janice VanCleave's 202 Oozing, Bubbling and Bouncing Experiments, "23, Twinkling Star", p. 15.



Mail Questions and Comments to:  Dale Stille