Acoustic and microwave resonances applied to measuring the gas constant and the thermodynamic temperature

Certain experimental and theoretical developments in acoustic and microwave techniques are reviewed, along with the progress in combining them to accurately measure u/c, the ratio of the speed of sound in a gas to the speed of light. Measurements of u/c in dilute monatomic gases can be used to determine the temperature of fixed points with unprecedented accuracy and to interpolate between them. This work also refers to the application of acoustic techniques to the redetermination of the universal gas constant.<
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