Volume 2, Issue 6, 01 June 1932
Index of content:
2(1932); http://dx.doi.org/10.1063/1.1745068View Description Hide Description
A physical picture of the phenomena during the electronic oscillation in the magnetostatic oscillator is given. The notion of a critical radius for plate voltages varying between a larger and a smaller value than the critical voltage for a given constant magnetic field is developed. The value of the critical radius is calculated as a function of the voltage differences and the potential distribution. The flying time of the electrons is discussed in its relation to the voltage distribution, and the falling angle is expressed in a simple way.
2(1932); http://dx.doi.org/10.1063/1.1745069View Description Hide Description
Y‐cut piezoelectricquartz plates were studied with respect to the charges developed on the plates when oscillating near their resonant frequencies. The attractive force between crystal and electrodes was measured. Two methods for determining the piezoelectric voltage developed across the crystal are suggested. It is concluded from a study of crystal breakage that fracture is due to intense mechanical vibration.
2(1932); http://dx.doi.org/10.1063/1.1745070View Description Hide Description
In electrical measurements and research work it is frequently necessary to have available a source of e.m.f. having a sine wave form. It is also desirable to be able to produce electrical wave forms having special contours. Existing means for producing special e.m.f. wave forms have serious limitations. By utilizing a continuously varying capacitance, means are developed whereby a pure sine wave, as well as special forms, may be produced. Filtering is not required. The theory underlying the production of any desired wave form is outlined. Factors which tend to modify the resultant wave form are pointed out.
2(1932); http://dx.doi.org/10.1063/1.1745071View Description Hide Description
Bubbles of gas when released in a liquid, at depths great compared to their diameters, on reaching the surface burst and eject droplets of the fluid into the air. Each bubble whose diameter is less than the critical value, on bursting simultaneously ejects many droplets. As many as seven droplets were observed for pure freshly‐surfaced water at 21°C for bubbles less than 0.12 cm in diameter, for benzene as many as four at 22°C when bubble diameters were less than 0.15 cm. For the same diameters maximum heights of 14.0 cm and 9.0 cm were found for water and benzene. Bubbles having diameters less than 0.10 cm eject droplets to heights which are proportional to the three‐halves power of the radius. Bubbles having greater diameters than those mentioned as critical, burst with less regularity, but always project larger droplets to lesser heights as the diameter increases. This irregularity is attributed to instability of the rising bubble. The height distribution h of the droplets at any single explosion is found to vary with the number n so that log h decreases proportionally as n increases. If a large number of droplets at a given height is examined for variation in distribution it is found that a sharp lower boundary exists but a more straggling distribution for the larger values of height. An analysis shows this to be approximately a Maxwellian distribution. The bursting bubble is accompanied by a gas vortex ring ejection, which assists in raising a liquid jet and stretching it beyond its stable configuration until it breaks into the exponentially distributed droplets mentioned above. After integrating this exponential drop distribution with respect to the integral number of drops observable it was found that the reconstructed jet had the form hx 2=constant. Because of the microscopic form of the jet no quantitative measurements could be made so that the converse case was considered, namely the jet produced by the reaction of a falling drop on a liquid surface, as presented by the photographic results obtained by Worthington. His jets when analysed as to volume gave the same mathematical expression as the one found from the data cited above. This reconstructed picture is offered as the solution of the mechanics of effervescence.
2(1932); http://dx.doi.org/10.1063/1.1745072View Description Hide Description
An apparatus for the microscopic measurement of fog particles is described. The particles were collected on a slightly greased glass slide and viewed with the aid of dark‐field illumination. The particle sizes were measured either visually with an eyepiece micrometer or, more usually, by the subsequent measurement of photomicrographs. With the aid of this apparatus a series of fog particle size distribution curves were obtained. These curves are characterized by a single maximum which always occurs at a particle diameter which is an integral multiple of 3.1 microns. The curves approach the axis asymptotically for large particle diameters but have a definite minimum. An explanation for this minimum on the basis of certain properties of the nuclei of condensation is offered.