- Sections
- A. General Materials & Mathematics
- B. Statics
- C. Kinematics & Dynamics
- D. Rotational Mechanics
- E. Gravitation & Astronomy
- F. Fluid Mechanics
- G. Vibrations & Mechanical Waves
- H. Sound
- I. Thermodynamics
- J. Electrostatics & Magnetostatics
- K. Electromagnetic Principles
- L. Geometrical Optics
- M. Wave Optics
- N. Spectra & Color
- O. Vision
- P. Modern Physics
H2-11. Sound Lens
Purpose
To demonstrate focusing of sound by refraction in a sound lens.
Equipment
Oscilloscope, oscillator, loudspeaker, microphone, and balloon with carbon dioxide.
Setup Time
10 min.
Images
Description
A balloon filled with carbon dioxide acts as a focusing sound lens, due to its convex shape and the smaller velocity of sound in the carbon dioxide. When the lens is inserted between the loudspeaker and the microphone, the sound wave is focused, increasing the sound level at the microphone, as seen on the oscilloscope. The source is either a small chunk of dry ice in a flask or a cylinder of carbon dioxide. For comparison, air (very little focusing) and helium (defocusing) balloons can also be used.
References
Haym Kruglak and Charles C. Kruse, A Visual Method For Demonstrating Refraction of Sound, AJP 8, 260-261, (1940).
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See pagesh1. nature of sound
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See pagesh2. wave properties of sound
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See pagesh3. standing sound waves
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See pagesh4. music
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See pagesh5. the ear
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See pagesh6. the voice
-
See pagesh1. nature of sound
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See pagesh2. wave properties of sound
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See pagesh3. standing sound waves
-
See pagesh4. music
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See pagesh5. the ear
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See pagesh6. the voice