written by Karen Williams

This experiment demonstrates the Debye-Sears Effect by using it to measure the velocity of sound in liquids or the wavelength of light for a medium with a known sound velocity. An ultrasound transducer produces sound waves downward into a liquid medium. The transducer creates rarefactions and compressions in the liquid. The medium becomes a liquid diffraction grating for laser light shone perpendicularly through it. The grating constant is half the wavelength of the ultrasound wave.

The Debye Sears Effect is first used to measure the wavelength of light in water. It is then used to measure the velocity of sound in cooking oil. The temperature of the fluids are considered in the experiment. The velocity of sound in liquids is an important value to measure as it is used to calculate the acoustic impedance and other physical properties of liquids.

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Last Modified July 19, 2019