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In the Classroom
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JCE DigiDemos: Tested Demonstrations
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Guitar Strings as Standing Waves: A Demonstration
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Michael Davis
Physical Science Department, Harold Washington College, Chicago, IL 60601
checked by:
Todd P. Silverstein
Department of Chemistry, Williamette University, Salem, OR 97301-3922
Dean J. Campbell
Department of Chemistry, Bradley University, Peoria, IL 61625-0208
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August 2007
Vol. 84 No. 8
p. 1287
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| Abstract |
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An undergraduate student's first exposure to modern atomic theory tends to start with Bohr's model of the atom. This familiar introduction to atomic structure also marks a general chemistry student's first foray into waves. Many popular chemistry textbooks illustrate the concept of a standing wave in the development of the modern quantum model by using the phrase “as seen on a guitar string”. In these illustrations, the wave itself is often small and difficult to discern. The same phenomenon, however, can be easily and audibly observed. This demonstration uses an acoustic guitar to produce three unique harmonic vibrations, each of which is representative of a standing wave and illustrates the concept of quantization. Manipulation of the guitar string to produce a standing wave is pervasive in popular music and is audibly recognizable. Lightly placing a finger on the 12th, 7th, or 5th fret and strumming any one or all six strings can produce an audible example of a standing wave on a guitar. This corresponds to a standing wave with 1, 2, or 3 nodes, respectively. Attempting to induce a node at other points on a guitar string does not generate a standing wave, due to destructive interference, thus no audible tone is produced.
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| More Information |
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Citation |
Davis, Michael. J. Chem. Educ. 2007, 84, 1287.
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Keywords |
Analogies / Transfer; Atomic Properties / Structure; Atomic Spectroscopy; Demonstrations; First-Year Undergraduate / General; High School / Introductory Chemistry; Physical Chemistry
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History |
Created:
Last Updated: |
6/22/2007
7/6/2007
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 Caution! | | Experiments, laboratory exercises, lecture demonstrations, and other descriptions of the use of chemicals, apparatus, instruments, computers, and computer interfaces are presented in the Journal of Chemical Education as illustrative of new or improved ideas or concepts in chemistry instruction and are directed at qualified teachers. Although every effort is made to assure and encourage safe practices and safe use of chemicals, the Journal of Chemical Education cannot assume responsibility for uses made of its published materials. Many chemicals are hazardous. Precautions for the safe use of hazardous chemicals and directions for their proper disposal are described in the Material Safety Data Sheets and on the labels. We strongly urge all those planning to use materials from our pages to make choices and to develop procedures for laboratory and classroom safety in accordance with local needs and situations. |
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