Synopsis
This book details the continued work to improve acoustical thermometry and explains how inconsistencies in previous measurements led to a redefinition of the NBS P2-20 (1965) scale. The author describes how an examination of the Helmholtz-Kirchhoff equation was made, and the maintenance of the P2-20 (1965) scale is presented. The book also includes a description of a new calibration apparatus that was constructed to accommodate more germanium thermometers, thus reducing the calibration cost per thermometer during a calibration run. Of particular note, in order to obtain values of the speed of sound as a function of pressure, the author determined the wavelength and the frequency. They did this by creating standing waves in a gas by means of an apparatus with a fixed frequency and a variable path. A quartz crystal, operating at its resonant frequency, radiates through helium gas to a reflector surface that is parallel to the quartz crystal; radiation is reflected back through the gas to the quartz crystal. If the spacing between the crystal and the reflecting surface is an integral number of half wavelengths, the helium gas will be in resonance and a peak voltage will be measured across the quartz crystal. The reflecting surface is displaced through detected integral numbers of half wavelengths and its displacement measured. Thus, the wavelength is determined, the frequency of the quartz crystal is measured and, consequently, the speed of sound can be calculated.
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Low Temperature Thermometry: Interim Report (Classic Reprint)
impression à la demandeVendeur : Forgotten Books, London, Royaume-Uni
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Paperback. Etat : New. Print on Demand. This book details the continued work to improve acoustical thermometry and explains how inconsistencies in previous measurements led to a redefinition of the NBS P2-20 (1965) scale. The author describes how an examination of the Helmholtz-Kirchhoff equation was made, and the maintenance of the P2-20 (1965) scale is presented. The book also includes a description of a new calibration apparatus that was constructed to accommodate more germanium thermometers, thus reducing the calibration cost per thermometer during a calibration run. Of particular note, in order to obtain values of the speed of sound as a function of pressure, the author determined the wavelength and the frequency. They did this by creating standing waves in a gas by means of an apparatus with a fixed frequency and a variable path. A quartz crystal, operating at its resonant frequency, radiates through helium gas to a reflector surface that is parallel to the quartz crystal; radiation is reflected back through the gas to the quartz crystal. If the spacing between the crystal and the reflecting surface is an integral number of half wavelengths, the helium gas will be in resonance and a peak voltage will be measured across the quartz crystal. The reflecting surface is displaced through detected integral numbers of half wavelengths and its displacement measured. Thus, the wavelength is determined, the frequency of the quartz crystal is measured and, consequently, the speed of sound can be calculated. This book is a reproduction of an important historical work, digitally reconstructed using state-of-the-art technology to preserve the original format. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in the book. print-on-demand item. N° de réf. du vendeur 9780428103194_0
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