| Description |
iv, 50 leaves : illustrations ; 29 cm |
| Summary |
"In acoustics the term ultrasonics is used to refer to those frequencies which are above the range of human hearing; that is, frequencies above approximately 20,000 cycles per second. Since the laws of sound which are valid for the audible range are also valid in the ultrasonic range and since the wave length of ultrasonics is much shorter than that of audible sound, ultrasonic has proved very valuable in the calculation of both the velocity and the absorption coefficient of sound in various media. This is especially notable in the case of liquids, where the velocity of sound is much higher than in air or other gases. Prior to the application of ultrasonic vibrations, the calculation of velocity of sound in liquids was beset with many difficulties, both experimental and interpretational, due to the long wave length (corresponding to a higher velocity) of sound in the liquids. Measurements of velocity of sound in water were made in large lakes or rivers where there could be no accurate value of the temperature, or of the amount of dissolved substances in the water. Any experimenter who attempted to measure the velocity of sound in a small container in the laboratory was met with many complications. Since the wave length of the sound was of the same order as the dimensions of the radiation surface, corrections must be made for the fact that these waves could not be considered plane; elastic reaction of the walls of the container introduced a complicated correction factor which was of appreciable magnitude in the audible range. Because of the above mentioned difficulties, and others, independent calculations of the velocity of audible sound in liquids, where comparable, have been characterized by their lack of consistency. Probably the best of the experiments by a resonance method in liquids at audible frequencies are those by Pooler, who has measured the Velocity of sound in distilled water as a function of temperature. Using a correction formula developed for the purpose by Gronwall, he corrected his results for the error introduced by the elastic reaction of the walls of the container. Most of the difficulties and corrections involved in the determination of the velocity of sound in liquids were eliminated by Hubbard and Loomis who applied the Pierce acoustic interferometer to liquids. In the work herein described the author has concerned himself primarily with the study of the various methods of measuring the velocity of ultrasonics in oil and in distilled water as functions of temperature using an adaptation of the ultrasonic interferometer for liquids. From the velocity thus obtained are calculated the adiabatic compressibility and the bulk modulus of distilled water"--Introduction, leaves 1-2. |
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