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Dec 1992

Volume 60, Issue 12, pp. 1065-1159

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The de Broglie relationship—Fact and fiction

Joan A. Henry

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1065

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03.65.Ta Foundations of quantum mechanics; measurement theory
01.65.+g History of science

Publications on military doctrine

Arthur A. Broyles

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1065

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01.75.+m Science and society
28.70.+y Nuclear explosions
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Editorial: Cold fusion

Robert H. Romer

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1067

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Abstract Unavailable
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01.30.-y Physics literature and publications
25.45.-z 2H-induced reactions
82.45.-h Electrochemistry and electrophoresis
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‘‘Frames of Reference’’ revisited

Alistair Steyn‐Ross and Donald G. Ivey

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1069 | Cited 1 time

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The PSSC teaching film, ‘‘Frames of Reference,’’ was made in 1960, and was one of the first audio‐visual attempts at showing how your physical ‘‘point of view,’’ or frame of reference, necessarily alters both your perceptions and your observations of motion. The gentle humor and original demonstrations made a lasting impact on many audiences, and with its recent re‐release as part of the AAPT Cinema Classics videodisc it is timely that we should review both the message and the methods of the film. An annotated script and photographs from the film are presented, followed by extension material on rotating frames which teachers may find appropriate for use in their classrooms: constructions, demonstrations, an example, and theory.    
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01.50.F- Audio and visual aids
45.05.+x General theory of classical mechanics of discrete systems

Does quantum mechanics obey the correspondence principle? Is it complete?

Joseph Ford and Giorgio Mantica

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1086 | Cited 13 times

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This elementary review paper presents the compelling evidence which supports the notion that quantum mechanics is much too simple a theory to adequately describe a complex world. Rigorous arguments based on algorithmic complexity theory are used to show that both the quantum Arnol’d cat and a broad category of finite, bounded, undriven, quantum systems do not obey the correspondence principle, implying that quantum mechanics is also not complete. An experiment, well within current laboratory capability, is proposed which can expose the inability of quantum mechanics to adequately describe macroscopic chaos. In its final section, this paper describes a theoretical framework that provides a proper setting for interpreting these surprising results.
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03.65.Ta Foundations of quantum mechanics; measurement theory
03.65.Ca Formalism

A narrow‐band tunable diode laser system with grating feedback, and a saturated absorption spectrometer for Cs and Rb

K. B. MacAdam, A. Steinbach, and C. Wieman

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1098 | Cited 87 times

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Detailed instructions for the construction and operation of a diode laser system with optical feedback are presented. This system uses feedback from a diffraction grating to provide a narrow‐band continuously tuneable source of light at red or near‐IR wavelengths. These instructions include machine drawings for the parts to be constructed, electronic circuit diagrams, and prices and vendors of the items to be purchased. It is also explained how to align the system and how to use it to observe saturated absorption spectra of atomic cesium or rubidium.
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42.60.By Design of specific laser systems
42.62.Fi Laser spectroscopy
42.25.Fx Diffraction and scattering

Railgun recoil, ampere tension, and the laws of electrodynamics

A. E. Robson and J. D. Sethian

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1111 | Cited 3 times

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There has recently been a revival of an old controversy over whether Ampere’s original law of force between current elements is to be preferred over the more familiar and universally used Biot–Savart–Lorentz law. Although it is agreed that the two laws give identical results when used to calculate the force between two circuits, it has been claimed that if Ampere’s law is applied to the action of a circuit upon part of itself it predicts internal longitudinal forces that are excluded by Biot–Savart–Lorentz. The existence of longitudinal forces has been inferred from observations of the buckling of the rails in a railgun, attributed to compressive stress, and the fracture of long wires subjected to pulsed currents, attributed to ‘‘Ampere tension.’’ An experiment has been performed that should provide an unambiguous demonstration of this longitudinal force, if it exists. The apparatus consisted of a rigid coaxial circuit in which an unsymmetrical section of the center conductor was free to move in the axial direction under the influence of the longitudinal force. Pulsed currents of up to 100 kA were passed through the circuit but no evidence of a longitudinal force was found. It is shown that this result is consistent with Ampere’s force law, and that claims that the law predicts longitudinal forces are based on the incomplete application of the law.
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41.20.-q Applied classical electromagnetism
75.80.+q Magnetomechanical effects, magnetostriction

Relativistic transformation of group velocity via spatial filtering

G. E. Stedman

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1117

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The group velocity of any wave transforms under Lorentz boosts as a particle velocity, and so by the Einstein velocity addition relations. This is expected for the velocity of energy transport in spite of the presence of a medium and so a preferred frame. The phase velocity has the same transformation property only when the group and phase velocities are parallel and the product of their magnitudes is equal to c2. A proof is given of the relativistic group velocity transformation which is simple and novel, and which uses spatial filtering concepts to derive the formula for group aberration as a consequence of that for phase aberration. This gives some physical insight into the previous proofs based on a four‐vector analysis.
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41.20.Jb Electromagnetic wave propagation; radiowave propagation
03.30.+p Special relativity

Thermodynamic properties of an anharmonic fermionic oscillator

S. M. de Souza, S. Moss de Oliveira, and M. T. Thomaz

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1122

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An exactly soluble fermionic system (anharmonic oscillator) is presented. Exact expressions for average quantities such as the number of particles, energy, and magnetization of an ensemble of quantum systems in equilibrium with a reservoir of particles and heat are derived. Critical curves of the average magnetization as a function of temperature are obtained for a lattice of interacting anharmonic oscillators within the mean field approximation. To clarify the role played by the parameters of the present model, the Ising model is studied as a limiting case.  
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03.65.Ge Solutions of wave equations: bound states
05.30.Fk Fermion systems and electron gas
05.50.+q Lattice theory and statistics (Ising, Potts, etc.)

Path integral approach to the small polaron model in the atomic limit

Miguel G. Cruz

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1127

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The formalism of functional integration in the holomorphic representation is illustrated by calculating the partition function for the small polaron Hamiltonian in the atomic limit. As an introduction, the standard construction of the functional integral representation of the partition function for a coupled fermion‐boson system is reviewed.
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71.38.-k Polarons and electron-phonon interactions
03.65.Ca Formalism
05.30.Ch Quantum ensemble theory

A note on energy minimization and the quantum‐mechanical virial theorem for the class of potentials V(x)=A‖x‖n

Harry A. Mavromatis

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1131

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It is pointed out that for the class of potentials V(x)=A‖x‖n, the quantum‐mechanical virial theorem 〈ϕm‖T‖ϕm〉=(n/2)〈ϕm‖V‖ϕm〉 is in fact valid for any multiparameter trial wave function ψt=(1/√b)ϕt (x/b,a0,a1,...ar), where a0,a1,...ar, are dimensionless parameters, provided b is chosen to minimize 〈ψt‖T+V‖ψt〉, i.e., one requires (∂/∂b)[〈ψt‖T+V‖ψt〉]=0. A particular trial wave function of this type is used to illustrate this result.
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03.65.Ge Solutions of wave equations: bound states

Magnetic dipole interactions on an air track

H. G. Lukefahr

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1134 | Cited 4 times

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General Physics Laboratory exercises which use permanent magnets and an air track to illustrate dipole–dipole interactions and mechanical stability are reported. These experiments, which use an apparatus reported previously, can be set up using equipment which is available in most physics departments. The experiments are particularly suitable for the transition from the study of classical mechanics to electricity and magnetism.  
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01.50.My Demonstration experiments and apparatus
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems
07.55.Db Generation of magnetic fields; magnets
85.70.-w Magnetic devices

Relativistic constitutive relations, differential forms, and the p‐compound

D. B. Nguyen

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1137

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This article introduces the reader to the physical applications of the concept of the p‐compound of a linear transformation L. The computation of p‐compounds requires nothing more than the computation of p‐order determinants and, therefore, has a simple geometric interpretation. While L acts on vectors, the p‐compound of L acts on geometric objects made up of p vectors: the two‐compound acts on parallelograms, the three‐compound acts on parallelopipeds, and so on. The physics is introduced by identifying the electromagnetic field quantities with parallelograms and parallelopipeds in space‐time; the p‐compound of the Lorentz transformation then yields their (algebraically complicated) relativistic transformations after one matrix multiplication. The relativistic electromagnetic properties of a medium are obtained by two matrix multiplications. In this way, one obtains the expression for the relativistic Biot–Savart law, an explanation for the experimental results of Röntgen and Wilson, an explanation for the null result of Michelson and Morley, and the Cerenkov condition for a charged particle to radiate while moving through a dielectric medium.
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03.30.+p Special relativity
03.50.De Classical electromagnetism, Maxwell equations
41.60.Bq Cherenkov radiation

Plücker’s relations and the electromagnetic field

D. B. Nguyen

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1145

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Every two‐dimensional parallelogram in three dimensions casts three parallelogram‐shaped shadows onto the three coordinate planes; the signed areas of these shadows are real numbers. Conversely, every set of three real numbers can always be identified with the signed areas of parallelogram‐shaped shadows of some one parallelogram. It is never necessary in three dimensions to invoke more than one parallelogram for this purpose. In higher dimensions, however, this converse is not true; to be the signed volumes of the p‐dimensional shadows of some one p‐dimensional parallelopiped in n dimensions, a set of numbers must satisfy several quadratic equations known collectively as Plücker’s relations. When the six electromagnetic field components (three electric, three magnetic) are viewed as signed areas of the shadows of a parallelogram in space time, all inertial observers must agree on the number of parallelogram. Plücker’s relations applied to these six numbers must, therefore, produce relativistic invariants.
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03.30.+p Special relativity
03.50.De Classical electromagnetism, Maxwell equations
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The parabolic envelope of constant initial speed trajectories

Denis Donnelly

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1149 | Cited 1 time

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Abstract Unavailable
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45.05.+x General theory of classical mechanics of discrete systems

How entropy got its name

Ralph Baierlein

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1151 | Cited 1 time

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01.65.+g History of science
05.70.Ce Thermodynamic functions and equations of state

Display of real‐space scattering in the Ewald construction

Richard L. Liboff

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1152 | Cited 1 time

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61.05.cc Theories of x-ray diffraction and scattering
81.10.Aj Theory and models of crystal growth; physics and chemistry of crystal growth, crystal morphology, and orientation
01.50.Kw Techniques of testing
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A high‐speed demonstration motor with superconducting bearings

Christopher Gabrys, John R. Hull, and Thomas M. Mulcahy

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1153 | Cited 1 time

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Abstract Unavailable
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84.71.Ba Superconducting magnets; magnetic levitation devices
07.55.Db Generation of magnetic fields; magnets
85.70.-w Magnetic devices
01.50.My Demonstration experiments and apparatus
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Why Do Authors Keep On Doing It?

Ralph Baierlein, Author

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1155

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Abstract Unavailable
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01.30.mp Textbooks for undergraduates
01.40.G- Curricula and evaluation

Surface Science: An Introduction

John B. Hudson, Author and Renee D. Diehl

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1155

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01.30.mp Textbooks for undergraduates
01.30.mm Textbooks for graduates and researchers
73.20.-r Electron states at surfaces and interfaces
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics

History of the Principle of Interference of Light

Nahum Kipnis, Author and Henry Steffens

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1156

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Abstract Unavailable
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01.30.Ee Monographs and collections
01.65.+g History of science
42.25.Hz Interference

POST‐USE REVIEW.Mathematica: A Practical Approach

Nancy Blachman, Author and William M. MacDonald

American Journal of Physics -- December 1992 -- Volume 60, Issue 12, pp. 1157

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Abstract Unavailable
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01.50.ht Instructional computer use
02.70.-c Computational techniques; simulations
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