An Experimental Determination of Ultrasonic Absorption and Reflection Coefficients in Air and in Carbon Dioxide

Abstract

Ultrasonic absorption coefficients in air and in carbon dioxide have been measured, as well as the coefficients of reflection in these gases at a solid boundary. In the frequency range between 88 and 1000 kc/sec. the absorption in air was found to increase with the square of the wave-length as required by classical theory, but for C${\mathrm{O}}_{2}$ the absorption constant of the classical theory rises to a sharp maximum at about 98 kc/sec. The reflection coefficient (brass reflector) was found to decrease with increasing frequency for both gases, the decrease being of the order of twenty percent at the higher frequencies. Measurements on an impure sample of helium are included.