Volume 11, Issue 1, January 1940
Index of content:
11(1940); http://dx.doi.org/10.1063/1.1751561View Description Hide Description
The Westinghouse WL‐759 ``trigger'' tube is designed to operate small relays and yet is controlled by currents less than 10−11 amp. in the starting anode circuit. Investigation shows that this is possible because of an ``avalanche'' effect set off by the radioactivity of the cathode after the starting anode has attained the critical potential for the efficient development of the high ion density needed to bring about the complete development of a glow discharge between the cathode and the principal anode of the tube. Other electrical characteristics of the tube are also discussed.
11(1940); http://dx.doi.org/10.1063/1.1751569View Description Hide Description
A magnetic beta‐ray spectrometer of high resolution has been constructed. The theory of the resolution of this instrument has been investigated in detail and applied to the design of the slit system. The effects of scattering within the vacuum chamber have been studied and reduced to a negligible value. The corrections for the efficiency of the Geiger‐Müller counter and for the absorption in the counter window have been obtained as a function of the momentum of the incoming particles.
11(1940); http://dx.doi.org/10.1063/1.1751557View Description Hide Description
This paper is a discussion of the effects, on the use of the electrostatic energy spectrograph for charged particles, of the field distortions at the edges of the spectrograph plates and in between the plates. These effects are evaluated and shown not to be negligible in measurements of highest precision. It is shown how, by properly locating the source and detector of charged particles, to eliminate these effects to the extent of a first approximation. The discussion is carried through for only one particular form of spectrograph plates, but the modifications necessary to make it applicable to any other form of spectrograph are adequately pointed out.
11(1940); http://dx.doi.org/10.1063/1.1751559View Description Hide Description
11(1940); http://dx.doi.org/10.1063/1.1751560View Description Hide Description
The volt and ampere sensitivity of a moving coil galvanometer is treated in terms of the electrical circuit, the galvanometer design, and the time used for taking observation. Only cases where the current is constant are discussed; ballistic use is not treated. The term ``resolution of galvanometer readings'' is suggested to describe the experimentally determined change in potential difference or current that can be measured with a stated probable error in a stated measuring time under actual working conditions. The use of a galvanometer as a deflecting, partial‐deflecting and null instrument is discussed.
11(1940); http://dx.doi.org/10.1063/1.1751562View Description Hide Description
Formulas are derived for the change in e.m.f. and current that can be resolved with a given precision in a given time for taking readings. The resolving power of the underdamped state (κ=0.8) is about 10 percent more favorable than for critical damping. Considering a galvanometer as an engine for converting electrical energy into potential energy shows that its effective efficiency is about 40 percent that of an ideal engine.
11(1940); http://dx.doi.org/10.1063/1.1751563View Description Hide Description
A constant path acoustic interferometer is described, which operates by varying the pressure of the gas being studied. This variation in pressure results in the appearance of standing waves between the crystal and reflector. The resulting reaction peaks, detected by the usual methods, allow of determination of the wave‐length, and consequently the velocity, if the frequency be known. Comparison is made of the results on ethylene gas at 23.0°C and pressures between 35 to 55 atmospheres obtained with this instrument and those of a moving reflector interferometer. The two sets of data agree within the limits of error of the measurements.
11(1940); http://dx.doi.org/10.1063/1.1751564View Description Hide Description
An apparatus and procedure is described for measuring electrical frequencies from 1 to 15 kc with an accuracy of 0.001 percent. The broadcast frequency of a radio station is subdivided to give 100.000 cycles. Beats between the unknown frequency and known integral multiples of the 100 cycles are then counted.
11(1940); http://dx.doi.org/10.1063/1.1751565View Description Hide Description
A simple method for construction of an ether‐vapor thermostat is described, and a relaycontrol system for accurate temperature control of rooms is given. With this arrangement, the temperature at specified localities in a room may be kept constant to less than 0.05°C over long periods of time.
11(1940); http://dx.doi.org/10.1063/1.1751566View Description Hide Description