November 2018 Issue, Volume 86, No. 11AJP November 2018


Visualizing sound waves with schlieren optics

Using schlieren optics as a tool to see the invisible, we describe a technique of visualizing traveling ultrasonic (28?kHz) sound waves in real time. Suitable for lecture demonstration purposes or as an instructional laboratory experiment, our setup can readily demonstrate the reflection of sound waves from surfaces, diffraction effects around objects, interference, and standing waves. Additionally, the incorporation of color filters provides information such as gradient directions and sound wave phase differences not obtainable with just a white light source. As an example, acoustic standing waves are analyzed.



Resource Letter PB-1: The Physics of the Brain by Christian G. Fink. DOI: /10.1119/1.5054288

Experimental verification of the adiabatic transfer in Wilberforce pendulum normal modes by M. Hübner, and J. Kröger. DOI: 10.1119/1.5051179

Relativistic description of the photoelectric effect by Julio Güémez, and Manuel Fiolhais. DOI: 10.1119/1.5052359

A hybrid approach for using programming exercises in introductory physics by C. M. Orban, R. M. Teeling-Smith, J. R. H. Smith, and C. D. Porter. DOI: 10.1119/1.5058449

Self-torque and angular momentum balance for a spinning charged sphere by Béatrice Bonga, Eric Poisson, and Huan Yang. DOI: 10.1119/1.5054590

Kepler's equation and some of its pearls by SFrancisco G. M. Orlando, C. Farina, Carlos A. D. Zarro, and P. Terra. DOI: /10.1119/1.5055760

Back of the Envelope

The exponential benefits of logarithmic thinking by Sanjoy Mahajan. DOI: 10.1119/1.5058771

Physics Education Research

Transforming the content, pedagogy and structure of an introductory physics course for life sciences majors by David P. Smith, Laurie E. McNeil, David T. Guynn, Alice D. Churukian, Duane L. Deardorff, and Colin S. Wallace. DOI: 10.1119/1.5058685

Apparatus and Demonstration Notes

Visualizing sound waves with schlieren optics by Allen Crockett, and Wolfgang Rueckner. DOI: 10.1119/1.5042245

Book Reviews

The Man Who Saw Tomorrow: The Life and Inventions of Stanford Ovshinsky by Brian Schwartz. DOI: 10.1119/1.5052429

The Great Silence: The Science and Philosophy of Fermi's Paradox by G. David Brin. DOI: 10.1119/1.5053112

Books Received

American Journal of Physics 86, 880 (2018); DOI:


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