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Vol. 6, No. 2 (1946)

1946-01-20
Topics
CONTENT
EFFECT OF SPACE CHARGE ON THE FREQUENCY OF OSCILLATION IN POSITIVE-GRID OSCILLATORS
Chai Yeh
1946, 6 (2): 1-7. doi: 10.7498/aps.6.1
Abstract +
In estimating the frequency of oscillation of a positive-grid oscillator, it isusually assumed that the space charge effect is negligible. Under this assumption, the potential distribution in the space between the plane-parallel electrodes is linear. Thus the electric field in the space is uniform and the average velocity of electrpn flight can be used to evaluate the frequency of oscillation. The presence of space charge affects the potential distribution in space so that the electric field in this region is no more constant. Hence more exact formula must be used to compute the frequency of oscillation. The calculation is further complicated by the fact that the anode potential is usually made slightly negative with respect to the cathode. In this case, the location of the virtual cathode at which the electrons turn back does not coincide with that if a straight line potential distribution were assumed. The predicated trequency of oscillation is about 10-20 percent lower than that if space charge were neglected.
ON THE HERMITEAN OPERATORS IN QUANTUM MECHANICS
H. C. Lee
1946, 6 (2): 8-21. doi: 10.7498/aps.6.8
Abstract +
The main purpose of this paper is, after making some necessary preliminaries on the theory ot linear differential operators in one real variable, to obtain the explicit condition that such an operator of any order be a Hermitean operator, and as application of the result point out various quantum-mechanical instances.
A PROBLEM IN THERMODYNAMICS
J. S. Wang
1946, 6 (2): 22-29. doi: 10.7498/aps.6.22
Abstract +
A simple problem in thermodynamics is considered with a view to emphasizing that the application of the adiabatic law pVγ=const, for a gas is permissible only when the process is quasistatic.
A NOTE ON THE NUMBER OF ISOTOPES
Yan Der Haw
1946, 6 (2): 30-33. doi: 10.7498/aps.6.30
Abstract +