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Dec 1978

Volume 46, Issue 12, pp. 1209-1292

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Editorial: Creativity lost

John S. Rigden, Editor

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1209

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Abstract Unavailable
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01.40.Di Course design and evaluation
01.40.G- Curricula and evaluation
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Uniqueness of Maxwell’s equations

Jack Cohn

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1210

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As a consequence of two feasible assumptions and close attention being given to the definitions of charge and the fields E and B, it is shown that the lowest‐order equations that these fields must satisfy are Maxwell’s equations.
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03.50.De Classical electromagnetism, Maxwell equations

The ball bearing as a motor

H. Gruenberg)

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1213 | Cited 9 times

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When a current is passed through a ball bearing it can act as a motor. This curious effect was pointed out by Milroy. The present paper gives a theoretical analysis of this effect. The motor can run in either direction on both dc and ac. It can be self‐starting on dc. Some experimental results are presented in support of the theory.
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84.30.-r Electronic circuits
03.50.De Classical electromagnetism, Maxwell equations

Experiment with the individualized laboratory system

E. Lagendijk, P. T. M. Niesten, W. van Willigen, and W. Wolthers

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1220

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A comparative experiment was carried out with two teaching forms of an introductory laboratory course for freshmen in physics. The results indicate that an individualized version of the course is more effective than a traditional version. The individualized version turns out to be more efficient in learning time but less efficient in teaching time per student. On the average, the students do not differ in their opinion about the attractiveness of the two versions, but the students of the individualized version think that they have spent their time more usefully than the students of the traditional version. There is some indication that the traditional version reinforces an existing positive attitude towards physics experimentation more than the individualized version does. Observations of students doing experiments in the traditional version of the course suggest that these experiments emphasize concrete aspects of experimentation, which may hamper the development of formal skills necessary for good experimental work.
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01.50.Qb Laboratory course design, organization, and evaluation

Calculation of the displacement current using the integral form of Ampere’s law

A. J. Dahm

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1227

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The magnetic field as a function of position between two capacitor plates during discharge is derived with the use of the integral form of Ampere’s law and real currents only. The displacement current must be included to obtain the same result for arbitrary choices of contours.
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03.50.De Classical electromagnetism, Maxwell equations

Examination of Eulerian and Lagrangian coordinate systems

Wilfred J. Remillard

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1228

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The relationship between Eulerian and Lagrangian coordinate systems is studied with the help of computer plots. A universal curve relating the spatial derivatives of particle displacement in the two systems acts as a basis for identifying such phenomena as shock and cavitation. Examples are given which illustrate the differences in the shape of a traveling wave as seen by observers in the two systems.
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01.50.ht Instructional computer use
83.10.Ff Continuum mechanics

A simple discrete model of scattering in a fluctuating inhomogeneous medium

Bruce J. West

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1236

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The intractibility of most scattering problems in continuous media is discussed and a simple discrete model for scalar wave scattering from inhomogeneities on a lattice is presented. The ’’exact’’ scattered wave solution is given in terms of the ratio of determinants. The amplitude of the average field scattered from a point reflector is related to the characteristic function of the fluctuations in the scatterer’s motion.
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42.25.Dd Wave propagation in random media
03.50.De Classical electromagnetism, Maxwell equations
41.20.Jb Electromagnetic wave propagation; radiowave propagation

Critique of the treatment of work

S. G. Canagaratna

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1241 | Cited 3 times

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The difficulties in the treatment of work are discussed. It is shown that it is useful to distinguish between the work done by the work source and the work received by the system. The former is in general greater than the latter. This inequality should be carefully distinguished from the inequality that compares the work received by the system in a change carried out quasistatically with the corresponding quantity for the same change carried out nonstatically. The conditions under which these two quantities may be compared are carefully examined. It is shown that in the general nonstatic case the work cannot be calculated in mechanical terms alone; we have to use the first law of thermodynamics.
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05.70.-a Thermodynamics
45.05.+x General theory of classical mechanics of discrete systems

String‐coupled pendulum oscillators: Theory and experiment

Michael J. Moloney

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1245 | Cited 2 times

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A coupled‐oscillator system is given which is readily set up using only household materials. The normal‐mode analysis of this system is worked out, and an experiment or demonstration is recommended in which one verifies the theory by measuring two times and four lengths.
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01.50.Pa Laboratory experiments and apparatus
45.05.+x General theory of classical mechanics of discrete systems

Note on the time‐dependent damped and forced harmonic oscillator

P. G. L. Leach

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1247 | Cited 4 times

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A Hamiltonian for the time‐dependent damped and forced harmonic oscillator is derived. A simple time‐dependent linear canonical transformation transforms the Hamiltonian to one whose solution is readily obtained. The wave function for the corresponding quantum mechanical problem is given.
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45.05.+x General theory of classical mechanics of discrete systems

Real variable inversion of Laplace transforms: An application in plasma physics

C. L. Bohn and R. W. Flynn

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1250 | Cited 3 times

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Laplace transform techniques are applicable to a wide variety of problems. The Bromwich inversion employing contour integration on the complex s plane is commonly used to invert untabulated transforms. Most physicists believe Laplace inversion must necessarily involve operations on the complex plane. This is not so. An alternative, the Widder inversion, uses real variables exclusively. We have applied Widder’s method to the problem of Landau damping, a notoriously difficult inversion, to illustrate the power of the techique.
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02.30.-f Function theory, analysis
52.25.-b Plasma properties

Aharonov‐Bohm effect in perturbation theory

Kay M. Purcell and Walter C. Henneberger

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1255 | Cited 8 times

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The Aharonov‐Bohm effect is obtained in first‐order perturbation theory. It is shown that the effect occurs only when the initial state is a superposition of eigenstates of Lz corresponding to eigenvalues having opposite sign. This corresponds to the two paths separated by the magnetic flux that are considered in usual discussions of the effect.
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03.65.-w Quantum mechanics

Velocity of energy flow

E. T. Newman

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1257

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We point out and discuss a frequently misunderstood, overlooked, or disregarded relationship between the energy‐momentum tensor and the velocity of energy flow.
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01.55.+b General physics
02.30.-f Function theory, analysis

Teaching relativity with a different philosophy

J. A. P. Angotti, I. L. Caldas, D. Delizoicov, Neto, E. Rüdinger, and M. M. C. A. Pernambuco

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1258 | Cited 3 times

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A teaching module on special relativity is described in which priority is given to attitudinal objectives as opposed to objectives of content. The implications of this for the methodology and the structure of the course are described. The functioning of the course material in practice is discussed together with some conclusions drawn from evaluations of the module.
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01.40.Di Course design and evaluation
03.30.+p Special relativity

The Physical Sciences Building at Washington State University

Miles J. Dresser and Alfred B. Butler

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1263

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The Physical Sciences Building at Washington State University is a 16‐story structure that cost 8.5 million dollars. It was completed in January 1974 and is occupied by the Departments of Physics and Geology. Features in the lecture halls include overhead projection for the major presentation format with at least two used in each room, regular slide or movie projection from the rear, student seating on individual pedestal chairs with a continuous table for each row, and demonstrations that are changed by rolling tables from the front exit of the lecture hall directly to the preparation area. The research and teaching labs were designed principally from the viewpoint of flexibility for changing needs. A review of the success of these designs is made from the vantage point of three years of occupancy.
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01.52.+r National and international laboratory facilities
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The brachistochrone for a material point with arbitrary initial velocity

T. M. Atanackovic

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1274

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Abstract Unavailable
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45.05.+x General theory of classical mechanics of discrete systems
02.40.-k Geometry, differential geometry, and topology

Comment on ’’The Hall effect in a flowing electrolyte’’

H. S. T. Driver

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1275 | Cited 1 time

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Abstract Unavailable
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03.50.De Classical electromagnetism, Maxwell equations
01.50.Pa Laboratory experiments and apparatus

Behavior of a single Langmuir probe in a magnetic field

J. T. Pytlinski, H. J. Donnert, and I. Alexeff

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1276 | Cited 1 time

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Abstract Unavailable
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01.50.Pa Laboratory experiments and apparatus
52.25.-b Plasma properties
52.40.-w Plasma interactions (nonlaser)

Charge induced by displacement of an ion

John J. Spokas

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1278

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Abstract Unavailable
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85.90.+h Other topics in electronic and magnetic devices and microelectronics (restricted to new topics in section 85)
41.90.+e Other topics in electromagnetism; electron and ion optics (restricted to new topics in section 41)

Calibration of prismatic spectra by means of Edser‐Butler bands

S. George and M. Voelker

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1280

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Abstract Unavailable
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42.79.-e Optical elements, devices, and systems
01.50.Pa Laboratory experiments and apparatus

Two‐parameter variational calculation for one‐dimensional two‐electron systems

I. Richard Lapidus

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1281 | Cited 2 times

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Abstract Unavailable
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03.65.-w Quantum mechanics
31.15.-p Calculations and mathematical techniques in atomic and molecular physics

Looking at projectile motion from a different angle

F. D. Medina

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1282

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Abstract Unavailable
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45.05.+x General theory of classical mechanics of discrete systems
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Atomic Nuclei and Their Particles

E. J. Burge, Author and Douglas S. Fielder, Reviewer

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1284

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Abstract Unavailable
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01.30.Ee Monographs and collections
21.10.-k Properties of nuclei; nuclear energy levels
21.60.-n Nuclear structure models and methods

The Properties of Nuclei

G. A. Jones, Author and Douglas S. Fielder, Reviewer

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1284

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Abstract Unavailable
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01.30.Ee Monographs and collections
21.10.-k Properties of nuclei; nuclear energy levels
21.60.-n Nuclear structure models and methods

Space and Time in the Modern Universe

P. C. W. Davies, Author and William B. Jones, Reviewer

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1284

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Abstract Unavailable
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01.30.mp Textbooks for undergraduates
98.80.-k Cosmology

A Practical Introduction to Electronic Circuits

Martin Hartley Jones, Author and Haven E. Bergeson, Reviewer

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1285

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Abstract Unavailable
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01.30.mp Textbooks for undergraduates
84.30.-r Electronic circuits

Fields and Particles

Francis Bitter, Author, Heinrich A. Medicus, Author, and Arthur R. Quinton, Reviewer

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1286

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Abstract Unavailable
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01.30.mp Textbooks for undergraduates
03.50.-z Classical field theories

Medical Physics

John R. Cameron, Author, James G. Skofronick, Author, and Russell K. Hobbie, Reviewer

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1287

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Abstract Unavailable
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01.30.mp Textbooks for undergraduates
87.50.-a Effects of electromagnetic and acoustic fields on biological systems
87.50.C- Static and low-frequency electric and magnetic fields effects
87.85.-d Biomedical engineering
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A Place to Live

Fred James, Producer and John Dowling, Reviewer

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1290

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Abstract Unavailable
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89.30.-g Fossil fuels and nuclear power
01.75.+m Science and society
01.50.F- Audio and visual aids

Solar Frontier

Melenco Productions Producer and John Dowling, Reviewer

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1290

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Abstract Unavailable
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89.30.-g Fossil fuels and nuclear power
01.75.+m Science and society
01.50.F- Audio and visual aids

The Empty Frame

Cliff Hoelscher, Producer, Jean Hoelscher, Producer, and Richard Mason, Reviewer

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1290

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Abstract Unavailable
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01.50.F- Audio and visual aids
01.60.+q Biographies, tributes, personal notes, and obituaries
94.80.+g Instrumentation for space plasma physics, ionosphere, and magnetosphere

Mars: Chemistry Looks for Life

Chemical Education Materials Study Producer and Jay M. Pasachoff, Reviewer

American Journal of Physics -- December 1978 -- Volume 46, Issue 12, pp. 1291

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Abstract Unavailable
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01.50.F- Audio and visual aids
96.30.Gc Mars
96.50.-e Interplanetary physics
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