Gas Lens



content.gif (1503 bytes)
 Code Number :   3B35.10

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.

Further information regarding legal liability in use of demonstrations and labs will be found on the web site Injuries in School/College Laboratories in USA.

The University of Iowa Disclaimers:  University of Iowa Disclaimer All Rights Reserved..

Condition :   Good  
Principle :   Focusing sound, gas lens.
Area of Study :  Acoustics   
Equipment :   Balloons, gases that are lighter or heavier than air.
Procedure :   Fill the balloon with air or some other gas.  Hold the balloon close to your ear and you should be able to find a spot where the balloon acts like a lens and focuses the sound.  Gases of different densities will give some interesting effects to the focused sound.
conbot.gif (53 bytes)


   References

Pietro Ferraro, "Optics with Balloons", TPT, Vol. 34, # 5, May 1996, p. 274.

T. R. Sandin, "Viscosity Won't Curve It", TPT, Vol. 24, # 2, Feb. 1986, p. 70.

Thomas B. Greenslade, Jr., "The Acoustic Lens", TPT, Vol. 16, # 2, p. 100, Feb. 1978

Richard Reis, "A Sound Lens", TPT, Vol. 6, # 1, Jan. 1968, p. 40.



Mail Questions and Comments to:  Dale Stille