摘要:

A novel formulation of classical dynamics in terms of differential operators is presented. The basis for this formulation is the direct application of the unfolding theorem for arbitrary times. The solution of a mechanical problem is given by the operator method as a Taylor series about the initial point. The classical operator formalism has similarities with quantum mechanics. It is shown that classical scattering can be described in terms of a classicalS-matrix operator. Examples are given.

ISSN:0002-9505    

DOI:10.1119/1.1974357

出版商:American Association of Physics Teachers    

年代:1968

数据来源: AIP

摘要:

The experiment of F. T. Trouton and H. R. Noble to detect the motion of the earth through the ether by means of electromagnetic torque on a charged, suspended, parallel-plate capacitor is reexamined. No previous explanation of the null result appears to be satisfactory because, as is shown herein, conventional relativistic electrodynamics predicts that the total electromagnetic field energy of the capacitor is different in the two orientations. Therefore, this combination predicts that the result shouldnotbe null. A new explanation of the null result is offered, based on a new equation for the energy densitydU/dVin the electricEand magneticHfields of a classical macroscopic charged body with a uniform speedβin units of the speed of light. This new equationdU/dV = (E2−H2)/8π(1−β2), in Gaussian unitsin vacuo, predicts that the total electromagnetic field energy of the capacitor is independent of its orientation in agreement with the null result of Trouton and Noble.

ISSN:0002-9505    

DOI:10.1119/1.1974358

出版商:American Association of Physics Teachers    

年代:1968

数据来源: AIP

摘要:

The exact solution of the two-spin Heisenberg model with an external field is obtained by means of a Green function technique. The results are compared with an approximate solution of Patterson and Southwell in which a Tyablikov decoupling approximation is used. The special problem associated with the calculation of the zero-frequency component of the correlation function is also discussed.

ISSN:0002-9505    

DOI:10.1119/1.1974359

出版商:American Association of Physics Teachers    

年代:1968

数据来源: AIP

摘要:

Approximate solutions, valid near the junction or distant from the junction, are derived for several simple junction semiconductor devices. These solutions are useful for quick calculations of trends. Several simple numerical examples are given.

ISSN:0002-9505    

DOI:10.1119/1.1974360

出版商:American Association of Physics Teachers    

年代:1968

数据来源: AIP

摘要:

A simple maser model consisting of a single-mode field coupled toNidentical two-level atoms is presented. The assumption of negligible statistical correlation between the atoms and the field, permits the Heisenberg equations of motion to be replaced by a self-consistent set of ordinary nonlinear differential equations. Relaxation terms and an energy source are introduced phenomenologically. The resulting equations exhibit a threshold, stable and unstable steady states, relaxation oscillations and, sometimes, spiking. The dynamic equations for the hydrogen maser and the rate equations of laser theory are derived as special cases. Also discussed are the maser amplifier, locking of a maser to an external signal, and the effects of cavity thermal noise.

ISSN:0002-9505    

DOI:10.1119/1.1974361

出版商:American Association of Physics Teachers    

年代:1968

数据来源: AIP

摘要:

Many contemporary lecture halls have been designed in conventional ways that tend to maximize the seating capacity but that overlook serious operational problems. A design is presented which, it is hoped, will overcome many of these problems.

ISSN:0002-9505    

DOI:10.1119/1.1974362

出版商:American Association of Physics Teachers    

年代:1968

数据来源: AIP

摘要:

This paper describes a simple, yet accurate, vacuum-tube electrometer that has proved very useful in the teaching laboratory for measuring the small currents involved in various modern physics experiments. Details of the circuit design and construction are given. In addition, an electrometer test setup is described and the results obtained with the electrometer here considered are presented. The results indicate that this unit has an over-all precision of better than 4% on its10−10 Afull-scale range and a response time (including the recorder) of less than12sec for full-scale travel following application of a step function input. A simple modification allowing measurement of resistances up to1011 Ωis also indicated.

ISSN:0002-9505    

DOI:10.1119/1.1974363

出版商:American Association of Physics Teachers    

年代:1968

数据来源: AIP

摘要:

In order to reduce the confusion associated with many of the introductory treatments of photometry, it is suggested that initially the concepts of radiation transfer be introduced in terms of the more familiar units of radiometry. The conversion to photometric units can then be accomplished by a straightforward integration. The approach is illustrated with five of the basic quantities of radiometry.

ISSN:0002-9505    

DOI:10.1119/1.1974364

出版商:American Association of Physics Teachers    

年代:1968

数据来源: AIP

摘要:

Lecture demonstrations and/or possible undergraduate laboratory experiments which underline the importance of the time-dependent motions in rotating fluids for geophysical and astrophysical problems are presented here. The secondary flows which occur when the container of a fluid in rigid-body rotation changes velocity, which lead to such well-known effects as the teacup flow and river meanders, and which have a profound influence on large scale natural fluid flow, are considered following the theoretical treatment of Greenspan and Howard. The demonstrations of this “spin-up” problem illustrate (a) the difference in spin-up times due to boundaries parallel and perpendicular to the rotation axis, (b) frictional boundary layer formation and induced secondary horizontal flow, and (c) the vertical velocities induced by flat bottom boundary velocity changes.

ISSN:0002-9505    

DOI:10.1119/1.1974365

出版商:American Association of Physics Teachers    

年代:1968

数据来源: AIP

摘要:

Experiments utilizing a low-energy accelerator and ancillary equipment are described. The experiments are suitable for use in physics laboratory courses.

ISSN:0002-9505    

DOI:10.1119/1.1974366

出版商:American Association of Physics Teachers    

年代:1968

数据来源: AIP