Code Number: 3B35.10
Demo Title: Gas Lens
Condition: Good
Principle: Focusing sound, gas lens
Area of Study: Oscillations & 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.
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.
- Daniel A. Russell, "Basketballs As Spherical Acoustic Cavities", AJP, Vol. 78, # 6, June 2010, p. 549.
- Derek C. Thomas, Kent L. Gee, R. Steven Turley, "A Balloon Lens: Acoustic Scattering From a Penetrable Sphere", AJP, Vol. 77, # 3, p. 197, March 2009.
- George M. Hopkins, "Refraction of Sound", Experimental Science, p. 164.