ISSN:0034-6748    

DOI:10.1063/1.1751821

出版商:AIP    

年代:1934

数据来源: AIP

摘要:

A more sensitive method for observing longitudinal modes in vibrating piezoelectric plates consists in measuring the changes in the optical path presented by these plates to a beam of light. This is simply and conveniently accomplished by placing the transparent piezoelectric plate in one arm of a Michelson interferometer so that one of the interfering beams passes through the plate. Where a Michelson interferometer is not available, this may be accomplished in the case of a thin plate by means of the thick‐film fringes formed by reflecting a beam of light from the two major surfaces of the plate. Changes in the optical path are dominated by the changes in the index of refraction of the vibrating plate. The variations of the index of refraction are markedly greater for the extraordinary ray of a light beam propagated along theY‐axis of aY‐cut quartz plate in which the compressional wave trains are propagated along the X‐axis. Preliminary observations regarding the variation of the index of refraction in other crystal cuts are also presented. A brief summary is given of the longitudinal modes which have been observed in plates of quartz and tourmaline.

ISSN:0034-6748    

DOI:10.1063/1.1751822

出版商:AIP    

年代:1934

数据来源: AIP

摘要:

The apparatus and technique are described for the growth of large, strain‐free, single crystals of zinc of any desired orientation. It is shown that a gross mosaic structure may occur in the beginning of the growth of a crystal but may be eliminated by a steep temperature gradient. The data show the necessity of satisfying certain growth conditions, namely, that the ratio of the temperature gradient to the rate of growth must be near a certain favorable, but not necessarily the same, value for each orientation.

ISSN:0034-6748    

DOI:10.1063/1.1751823

出版商:AIP    

年代:1934

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751824

出版商:AIP    

年代:1934

数据来源: AIP

摘要:

During the vibration of a free reed the flow of the maintaining wind is more rapid on the low pressure side of the tongue, and consequently the reduction of pressure on that side is the greater. The inertia of the air causes the resulting pressure difference to have a component in phase with the velocity of the tongue, thus making maintenance possible. A similar explanation is given for the maintenance of Rayleigh's ``tuning fork siren.''

ISSN:0034-6748    

DOI:10.1063/1.1751825

出版商:AIP    

年代:1934

数据来源: AIP

摘要:

The requirements to be met by a cell for routine determinations of the resistivity of insulating oils are given. A guard‐ring cell meeting these requirements is described, and its application to power factor measurements discussed.

ISSN:0034-6748    

DOI:10.1063/1.1751826

出版商:AIP    

年代:1934

数据来源: AIP

摘要:

The origin of noise in vacuum tube amplifiers is discussed. An amplifier is described which can be used for the measurement of low voltages. A type 38 tube operated below ionizing voltages of the gas in the tube is found to have a low noise level. 10−8volt can be measured in the audiofrequency range.

ISSN:0034-6748    

DOI:10.1063/1.1751827

出版商:AIP    

年代:1934

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751828

出版商:AIP    

年代:1934

数据来源: AIP