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ERIC Number: EJ1000730
Record Type: Journal
Publication Date: 2012-Nov
Pages: 3
Abstractor: As Provided
ISSN: ISSN-0031-921X
Bubbles That Change the Speed of Sound
Planinsic, Gorazd; Etkina, Eugenia
Physics Teacher, v50 n8 p458-460 Nov 2012
The influence of bubbles on sound has long attracted the attention of physicists. In his 1920 book Sir William Bragg described sound absorption caused by foam in a glass of beer tapped by a spoon. Frank S. Crawford described and analyzed the change in the pitch of sound in a similar experiment and named the phenomenon the "hot chocolate effect." In this paper we describe a simple and robust experiment that allows an easy audio and visual demonstration of the same effect (unfortunately without the chocolate) and offers several possibilities for student investigations. In addition to the demonstration of the above effect, the experiments described below provide an excellent opportunity for students to devise and test explanations with simple equipment. (Contains 1 table and 3 figures.)
American Association of Physics Teachers. One Physics Ellipse, College Park, MD 20740. Tel: 301-209-3300; Fax: 301-209-0845; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Descriptive
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A