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Oct 1991

Volume 59, Issue 10, pp. 871-959

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Remember the consumer

Robert N. Varney

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 871

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Abstract Unavailable
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01.40.-d Education
01.75.+m Science and society

In defense of Marie Curie

T. M. Semkow and K. W. Semkow

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 871

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01.60.+q Biographies, tributes, personal notes, and obituaries
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Guest Comment: Military applications of technology—A new turn

Edward Teller

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 873

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01.75.+m Science and society
89.20.Bb Industrial and technological research and development
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Resource Letter LS‐1: Laser spectroscopy

R. Gupta

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 874

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This Resource Letter provides a guide to literature on laser spectroscopy. Emphasis has been placed on various spectroscopic techniques rather than the results obtained by the laser spectroscopy. The letter E after an item indicates elementary level or material of general interest. The letter I, for intermediate level, indicates material of somewhat more specialized nature; and the letter A indicates rather specialized or advanced material. An asterisk (∗) indicates articles to be included in an accompanying Reprint Book.
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01.30.Rr Surveys and tutorial papers; resource letters
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.60.Rd Visible and ultraviolet spectrometers
07.77.-n Atomic, molecular, and charged-particle sources and detectors
37.20.+j Atomic and molecular beam sources and techniques
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Rotating coordinates and the Ramsey separated oscillating‐field resonance method

Michèle Glass‐Maujean and H. Henry Stroke

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 886

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Norman Ramsey has recently been awarded the Nobel Prize for the ‘‘molecular beam resonance method with separated oscillating fields’’ [Phys. Rev. 78, 695–699 (1950)]. It is shown explicitly, for pedagogical purposes, how the use of rotating‐coordinate systems, introduced by Rabi et al. [Rev. Mod. Phys. 26, 167–171 (1954)] for the solution of magnetic‐resonance problems can be extended to the case of Ramsey’s method with separated oscillating fields.
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07.77.-n Atomic, molecular, and charged-particle sources and detectors
37.20.+j Atomic and molecular beam sources and techniques
33.25.+k Nuclear resonance and relaxation

Learning to think like a physicist: A review of research‐based instructional strategies

Alan Van Heuvelen

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 891 | Cited 24 times

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Many studies in physics education indicate that our conventional instruction fails to achieve objectives we desire for our students. Students leave introductory courses unable to reason qualitatively about physical processes. They use primitive formula‐centered problem‐solving techniques. Their minds contain a small number of facts and equations that are accessible only by random searches. In recent years, research by scientists interested in cognition and pedagogy has shown that we can do much better. This paper reviews this research and the instructional strategies that are suggested by it. The following paper reports the preliminary results of using these strategies in introductory physics courses that emphasize problem solving.
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01.40.G- Curricula and evaluation
01.55.+b General physics

Overview, Case Study Physics

Alan Van Heuvelen

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 898 | Cited 14 times

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Overview, Case Study (OCS) Physics is an effort to integrate recent results from physics education research into instruction for introductory university physics courses that emphasize problem solving. Students actively construct a knowledge hierarchy on a foundation of qualitative understanding. They analyze physical processes and problems using methods similar to those used by experienced scientists. Students receive repeated exposure to concepts in a variety of contexts over an extended time interval. Preliminary trials of OCS Physics have produced promising gains in student qualitative understanding, in their ability to solve problems, and in their ability to form and access a knowledge hierarchy.
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01.40.G- Curricula and evaluation
01.55.+b General physics

Dynamical symmetry breaking and chaos in Duffing’s equation

Collin L. Olson and M. G. Olsson

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 907 | Cited 2 times

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In certain frequency ranges a nonlinear damped and driven oscillator will respond asymmetri‐cally even though the potential energy is a single symmetric well. This dynamical symmetry breaking heralds the onset of a period doubling transition to chaos.
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05.45.-a Nonlinear dynamics and chaos
45.05.+x General theory of classical mechanics of discrete systems

Classroom exercises with the Terrell effect

John Robert Burke and Frank J. Strode

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 912 | Cited 2 times

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Because of the finite speed of light, the photographic appearance of a relativistic body would not simply show a Lorentz contraction. In its simplest version, this effect provides exercises, accessible to undergraduates, that illustrate concepts of simultaneity and use of the Lorentz transformation. Transformation of light intensity also provides useful exercises and interesting results.
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03.30.+p Special relativity

Externally excited semi‐infinite one‐dimensional models

Sergio A. Cannas and Domingo Prato

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 915

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The problem of a semi‐infinite harmonic chain with the first mass subject to a forced periodic motion is solved exactly. The scattering of a quantum particle by a semi‐infinite Kronig–Penney chain is analyzed analytically. The behavior of extended and localized solutions is analyzed in both problems and many analogies are found between them. Special attention is paid to the asymptotic behavior of localized solutions near the band edges.
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68.35.Ja Surface and interface dynamics and vibrations

A didactical approach to nontrivial dispersion relations

R. Delellis and F. Minotti

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 920

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A first approach to nontrivial dispersion relations is presented. Some properties of these relations corresponding to dispersive and/or dissipative phenomena are analyzed by studying the surface waves in a viscous liquid of infinite depth.
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41.20.Jb Electromagnetic wave propagation; radiowave propagation
47.35.-i Hydrodynamic waves

The quantum bouncer by the path integral method

D. A. Goodings and T. Szeredi

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 924 | Cited 3 times

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The path integral formulation of quantum mechanics in the semiclassical or WKB approximation provides a physically intuitive way of relating a classical system to its quantum analog. A fruitful way of studying quantum chaos is based upon applying the Gutzwiller periodic orbit sum rule, a result derived by the path integral method in the WKB approximation. This provides some motivation for learning about path integral techniques. In this paper a pedagogical example of the path integral formalism is presented in the hope of conveying the basic physical and mathematical concepts. The ‘‘quantum bouncer’’ is studied—the quantum version of a particle moving in one dimension above a perfectly reflecting surface while subject to a constant force directed toward the surface. The classical counterpart of this system is a ball bouncing on a floor in a constant gravitational field, collisions with the floor being assumed to be elastic. Path integration is used to derive the energy eigenvalues and eigenfunctions of the quantum bouncer in the WKB or semiclassical approximation. The results are shown to be the same as those obtained by solving the Schrödinger equation in the same approximation.
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03.65.Db Functional analytical methods

On the use of direct variational methods to study confined quantum systems

J. L. Marin and S. A. Cruz

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 931 | Cited 2 times

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The direct variational method is used to study two simple confined systems, namely, the hydrogen atom and the harmonic oscillator within impenetrable spherical boxes. The trial wave functions have been assumed as the product of the ‘‘free’’ solutions of the corresponding Schrödinger equation and a simple function that satisfies the respective boundary conditions. The energy levels obtained in this way are extremely close to the exact ones, thus proving the utility of the proposed method. This might constitute a complementary exercise for undergraduate students since usual quantum mechanics textbooks do not explore the use of the variational method to study confined systems.
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03.65.Db Functional analytical methods
03.65.Ge Solutions of wave equations: bound states

An analytical example of renormalization in two‐dimensional quantum mechanics

Lawrence R. Mead and John Godines

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 935 | Cited 12 times

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As a concrete example of the idea of renormalization, quantum mechanical scattering of particles by a two‐dimensional delta‐function potential is considered. The renormalization of the scattering cross section is carried out exactly and analytically. The calculation, free from obscuring mathematical details required for realistic field theories, may aid in making the idea of renormalization more accessible.
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03.65.Nk Scattering theory
03.65.Db Functional analytical methods

Boundary effects in quantum mechanics

David H. Berman

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 937 | Cited 4 times

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A simple formula is presented for the change in energy of a quantum system in a box when the box is infinitesimally deformed. The result is applied to rederive a formula given by Barton et al., [Am. J. Phys. 58, 751–755 (1990)] for the difference in energy of a bound state calculated with and without box boundary conditions. The formula can also be used to discuss pressure in a quantum system. A generalization of the result has been used for calculating scattering amplitudes for waves scattered by a rough extended surface. Here, a similar manifestly reciprocal result is derived for scattering by bounded objects.
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03.65.Ge Solutions of wave equations: bound states
03.65.Nk Scattering theory
03.65.Db Functional analytical methods

A pedagogical approach to the radiation fields

Allan Walstad

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 941

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A pedagogical approach to the emission of electromagnetic radiation is outlined in which Maxwell’s equations are solved directly for E and B without making use of the vector and scalar potentials.
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03.50.De Classical electromagnetism, Maxwell equations

Finite eigenfunctions in the WKB approximation

U. Sukhatme and A. Pagnamenta

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 944

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A long‐standing problem and major shortcoming of semiclassical (WKB) bound‐state wave functions is their divergence at the classical turning points. Presently available regularization schemes are accurate but rather complicated. It is shown how finite wave functions can be simply obtained by reorganizing the WKB perturbation expansion in powers of ℏ and retaining appropriate higher‐order terms. The wave functions obtained by this method are compared with exactly known ones for the harmonic‐oscillator and Morse potentials.
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03.65.Ge Solutions of wave equations: bound states
03.65.Sq Semiclassical theories and applications
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Comment on ‘‘Are sound waves isothermal or adiabatic?’’ by Junru Wu [Am. J. Phys. 58, 694–696 (1990)]

Pieter B. Visscher

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 948 | Cited 1 time

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43.20.Bi Mathematical theory of wave propagation
51.40.+p Acoustical properties
51.30.+i Thermodynamic properties, equations of state

The radial field of the Helmholtz pair

P. N. Murgatroyd

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 949 | Cited 2 times

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Abstract Unavailable
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41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems
84.32.Hh Inductors and coils; wiring

A surprising mechanics demonstration

A. R. Marlow

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 951 | Cited 1 time

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Abstract Unavailable
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01.50.My Demonstration experiments and apparatus
45.05.+x General theory of classical mechanics of discrete systems

Benford’s law and physical constants: The distribution of initial digits

John Burke and Eric Kincanon

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 952

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Abstract Unavailable
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02.10.De Algebraic structures and number theory
06.20.Jr Determination of fundamental constants

Relativistic transformation of the spectrum of radiation

Adam Kujawski

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 953

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Abstract Unavailable
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03.30.+p Special relativity

Gravitational field strength inside the Earth

Laurent Hodges

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 954

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Abstract Unavailable
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91.35.-x Earth's interior structure and properties
91.10.-v Geodesy and gravity

Erratum: The quantum mechanical Hamiltonian in curvilinear coordinates: A simple derivation [Am. J. Phys. 58, 344–347 (1990)]

Henrik Grum Kjaergaard and Ole Sonnich Mortensen

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 956

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Abstract Unavailable
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03.65.Ca Formalism
99.10.Cd Errata
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A new tube for Richardson–Dushman experiments

Thomas B. Greenslade, Jr.

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 957 | Cited 1 time

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Abstract Unavailable
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01.50.Pa Laboratory experiments and apparatus
84.47.+w Vacuum tubes
79.40.+z Thermionic emission
73.30.+y Surface double layers, Schottky barriers, and work functions
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The Physics of Musical Instruments

Neville H. Fletcher, Author, Thomas D. Rossing, Author, and Robert M. Williamson

American Journal of Physics -- October 1991 -- Volume 59, Issue 10, pp. 959

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Abstract Unavailable
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01.30.Rr Surveys and tutorial papers; resource letters
43.10.Hj Books and book reviews
43.75.-z Music and musical instruments
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