bluuebunny/crossref_metadata_2025 huggingface dataset:
What you see is what you get!
Authors: Harrison David
Published: March 2005

The issue of observability and the relative roles of the senses and reason in understanding the world is reviewed. Eastern ’’mystical’’ philosophy is used as a focus in which interpretations of quantum mechanics, as well as the current bootstrap-quark controversy, can be seen in some slightly different contexts than usual.
Limiting spectra from confining potentials
Authors: Nieto Michael Martin , Simmons L. M.
Published: March 2005

For confining potentials and large quantum numbers, the bound-state energies rise more rapidly as a function of n the more rapidly the potential rises with distance. However, the spectrum can rise no faster than n2 in the nonrelativistic case, or n in the relativistic case.
Development of canonical transformations from Hamilton’s principle
Authors: Quade C. Richard
Published: March 2005

It is shown that the variations δqj and δQi cannot both be simultaneously zero at the limits of integration in application of Hamilton’s principle to the development of the theory of canonical transformations. This means that δF1 does not vanish. However, the derivation requires only that the δqj be zero at the end points. This lack of symmetry between the qj and Qi in the formulaion is noted with respect to the Lagrangian and the fundamental commutator relations of quantum mechanics. Further, what is meant by an independent variation of pj and qj (or Qi and Pi) in the formalism is discussed in the use of Hamilton’s principle in the derivation of Hamilton’s equations of motion.
Structure and vibrational behavior of interstitial atoms in metals: An air table demonstration
Authors: Lehmann Christian
Published: March 2005

Magnetic cylinders on an air table behave similarly to atoms in many face-centered metals like aluminum or copper. They qualitatively exhibit the striking properties of a split-interstitial point defect (dumbbell): the structure, the localized and resonance vibration modes of a symmetric dumbbell; its effect upon the shear modulus; and the structure of an unsymmetric (mixed) dumbbell, containing a foreign atom. All effects can be shown to a large audience by means of a transparent air table put on an overhead projector.
Group theoretical interpretation of von Neumann’s theorem on composite systems
Authors: Bergia S. , Cannata F. , Ruffo S. , Savoia M.
Published: March 2005

We show that the physical meaning of a mathematical theorem on composite systems (described quantum mechanically) established by von Neumann becomes transparent with reference to a physical example, i.e., that of a composite system in a state of definite angular momentum. In this case the theorem is shown to reproduce the Clebsch-Gordan expansion, a fact which has been universally ignored. The theorem has a more general validity, the only condition being the existence of a conservation law, or, in other terms, of an underlying group structure (at least for cases of physical interest). This circumstance, in the case of non-Abelian groups, proves essential in the discussion of the Einstein, Podolsky, Rosen paradox and related problems.
Spatial Bose-Einstein condensation
Authors: Masut Remo , Mullin William J.
Published: March 2005

Three examples of spatial Bose-Einstein condensations in which the particles macroscopically occupy the lowest localized state of an inhomogeneous external potential are analyzed. The three cases are (a) a small potential well in a large box which causes a spectrum with a gap, (b) a harmonic oscillator potential, and (c) randomly sized trapping potentials caused by ’’impurities.’’ All three cases are two dimensional so that no Bose condensation occurs without the inhomogeneous potentials. An attempt is made to keep the treatments as mathematically simple as possible. A review of much of the literature of spatial Bose condensations is provided. The special problem of the form of the thermodynamic limit in an inhomogeneous potential is discussed for case (b). Numerical examples applying to monolayer 4He adsorbed on a surface are treated.
Diffraction of a laser beam
Authors: Jodoin Ronald E.
Published: March 2005

The effect of the nonuniform irradiance across a laser beam on diffraction of the beam is investigated. Calculations of Fraunhofer diffraction by a circular aperture show the deviations which occur from the usual Airy disk for several relative spot and aperture sizes.
Oscillations of a particle attached to a heavy spring: An application of the Stieltjes integral
Authors: Weinstock Robert
Published: March 2005

The normal-mode motions of a massive particle and a spring of non-negligible mass to whose end it is attached are shown to be described by ’’nonorthogonal’’ displacement functions. Two equivalent methods of establishing an orthogonality relation — a specially defined inner product and application of the Riemann-Stieltjes integral — are introduced. The results lead to the complete solution for the general motion of the spring-plus-particle system. This solution is applied to provide rigorous justification of the intuitive method that leads to the familiar rule (’’... add one-third the mass of the spring ...’’) for obtaining the period of a particle oscillating at the end of a uniform spring whose non-negligible mass is small in comparison. It is shown that the presence/absence of gravity is irrelevant to the general conclusions reached.
Demonstration of dispersive effects
Authors: Kunhardt E. E. , Cross R. C.
Published: March 2005

A method to simulate the dispersive properties of various media is described. We have used it to demonstrate to an Electromagnetic Theory class, the dispersion of a pulsed electromagnetic wave propagating in an unbounded dielectric medium. In addition, the characteristics of the electromagnetic precursors (Sommerfeld and Brillouin) have also been demonstrated.
Two-capacitor problem: A more realistic view
Authors: Powell R. A.
Published: March 2005

A popular circuit problem encountered in introductory physics and electromagnetics texts is discussed here in a more realistic manner by considering the self-inductance of the circuit. For practical values of the circuit parameters, the model usually put forth to solve this problem, a series RC circuit, appears inappropriate.
A rolling pendulum bob: Conservation of energy and partitioning of kinetic energy
Authors: Helrich Carl , Lehman Thomas
Published: March 2005

A novel pendulum is described and analyzed; its spherical bob can roll on a track of the same arc as its swing when suspended by a cord. Comparison of the motion in the two cases shows the effect of the rotational motion in rolling. The motion is analyzed with and without the Lagrangian, and is thus appropriate to analytical mechanics or general physics courses.
Abrupt depletion layer approximation for the metal insulator semiconductor diode
Authors: Jones Kenneth
Published: March 2005

The excess surface charge carrier density, surface potential, and relative capacitance of a metal insulator semiconductor diode are determined as a function of the gate voltage using the precise equations and equations derived using the abrupt depletion layer approximation. Calculations are made for different insulator thicknesses, doping concentrations, and temperatures. The results are compared, and their differences are discussed. It is shown that the results are similar except at the accumulation-depletion and depletion-inversion transition regions.
Student experiments on parametric resonance
Authors: Falk Lars
Published: March 2005

Some experiments on parametric effects, to be constructed by the students themselves, are described together with the discussion and questions given. Parametric oscillations were produced on a string, in a resonance circuit and a spring pendulum. The importance of phase relations for excitation of the oscillations and of nonlinearities in their stabilization was emphasized. The experiments were so organized that the students would meet unknown phenomena and problems; actually we discovered an unexpected recurrence effect in the spring pendulum.
Demonstration of phase relationships in a series R
L
C circuit using a four-channel multiplexer and a single-channel oscilloscope
Authors: Clay Forrest P.
Published: March 2005

An effective demonstration of the phase relationships in a series RLC circuit, resonance and Q, is made possible by multiplexing four signals onto a single channel thereby converting a single-channel scope to four channels. With the circuit explained in the text, it is possible to present a simultaneous display of VR, VL, VC, and Vgen on a single-channel scope. When the RLC circuit is excited by a variable frequency generator, VR becomes the reference phase. The time base ramp amplitude is made independent of the generator frequency by the circuit permitting four cycles of each waveform to always be in view on the scope, even though the generator frequency is varied from approximately 800 Hz to 18 KHz.
Calculations of cascade decay processes using rudimentary probability theory
Authors: Zivitz Maury
Published: March 2005

The established system of equations describing successive decay transitions of quantum systems is rederived here with the use of elementary theorems of probability theory. This new derivation has a quantum-mechanical foundation and thus provides more insight into the system than derivations of the early investigators. The development might be more appealing to applied physicists than more recent derivations which require a knowledge of the theory of Markov chains.
Doubling your sunsets or how anyone can measure the earth’s size with wristwatch and meterstick
Authors: Rawlins Dennis
Published: March 2005

A method is described whereby, using primitive equipment, anyone can measure the size of the Earth, to an accuracy of order of magnitude 10% — by observing two sunsets in the space of a few seconds. The calculated result’s closeness to the truth is comparable to the best extant ancient estimates.
Projectile motion revisited
Authors: Lucie Pierre
Published: March 2005

The power of symmetry and simple geometrical arguments is demonstrated in this somewhat unusual treatment of projectile motion. Keeping calculus and trigonometry manipulations to a bare minimum, the motion is analyzed in its greatest generality. Direction of velocity at any point, range, time of flight, maximum height, safety parabola, and maximum range are deduced for a projectile launched upon a plane inclined at any angle with respect to the horizontal.
Dilemma of the primary colors
Authors: Edge R. D. , Howard R.
Published: March 2005

It is an enigma for students why artists use red, yellow, and blue as primary colors, whereas physicists use red, green, and blue. To answer this problem, the spectra of a series of mixtures of red, green, blue, and yellow tempera (poster paints) were obtained using a Carey spectrophotometer with an integrating sphere. Points on the chromaticity diagram were obtained from the spectra, showing that whereas the mixture of yellow and blue yielded a fairly saturated green, the path of mixtures of green and red traveled on the blue side of the white point. Hence yellow is preferable as a primary color than green for tempera.
Permutation operator: An explicit representation
Authors: Schmid G. Bruno
Published: March 2005

An explicit representation of the permutation operator in terms of coordinate and momentum operators is derived.
Exact solution of a Faraday’s law problem that includes a nonlinear term and its implication for perturbation theory
Authors: Fulcher Lewis P.
Published: March 2005

An exact solution of a Faraday’s law problem with a nonlinear term is presented. The results are compared with those obtained by the perturbation methods of Poisson and Poincaré and of Kryloff and Bogoliuboff. The reasons for the superiority of the latter method are enumerated.
Probabilistic description of radioactivity based on the good-as-new postulate
Authors: Barnett Charles S.
Published: March 2005

The good-as-new postulate applied to radioactivity says: The conditional probability that a radioactive atom will ’’live’’ past time s+t, given that it has lived past time s, is equal to the unconditional probability that it would have lived past time t, starting from time zero. This postulate leads directly to the conclusion that the decay time of a radioactive atom is an exponentially distributed random variable. Add the postulate that the decay times of individual atoms in an aggregrate of identical radioactive atoms are independent, and a complete description of the random behavior of an aggregrate can be constructed. This approach stresses from the outset the randomness inherent in the radioactive decay process and is offered as a complement to the deterministic approach that treats fluctuations about mean values. All results are exact within the context of the model and are applicable to aggregrates of any size—no assumptions about large numbers are required.
The great beer bottle experiment
Authors: Smith Gary R. , Loly P. D.
Published: March 2005

We describe a low budget experiment, using materials that are easily obtained, to measure the speed of sound with an error of less than 10%. The device consists of a Helmholtz resonator of cylindrical cross section (a standard 12-oz beer bottle). The system is analogous to a mass vibrating on a spring. The resonant frequency is determined by the mass of the air plug located in and near the bottle neck and the spring constant associated with the elasticity of the air filling the remainder of the bottle. A simple procedure involving length measurements with a vernier caliper is outlined and a discussion of the approximations made in arriving at this procedure is presented.
Cognitive repression in contemporary physics
Authors: Keller Evelyn Fox
Published: March 2005

After more than 50 years of unquestionable success as a theory, questions about the interpretation of quantum mechanics continue to plague both physicists and philosophers. It is argued here that discussions about the meaning of quantum mechanics remain stymied as a result of the failure of physicists to formulate a cognitive paradigm adequate to their theory. The conventional interpretations which they offer can be seen as inadequate in one of two ways — implicitly, they retain one or the other of the two basic tenets of classical physics, the objectivity or the knowability of nature. This, it is argued, can be viewed as a form of cognitive repression of knowledge acquired, but not yet assimilated. A psychological explanation for the persistence of classical beliefs is proposed.
Discharge time for a capacitor
Authors: Cleveland Joseph R. , Hirschi Stanley
Published: March 2005

The complete discharge of a capacitor through a real resistor is limited by thermal noise. A meaningful discharge time td is defined by equating the charge across the capacitor in a noiseless RC circuit to the rms charge fluctuation in a noisy circuit Q0(td) =[〈 (δQ)2〉t]1/2. Three derivations are reviewed for the well-known result 〈 (δQ)2〉t=kTC. One derivation shows explicitly that δQ (t) can be determined with the noise current in(t) as its source. Several examples of potential interest in the classroom are discussed.
Correlation between logical abilities and success in physics
Authors: Liberman Dov , Hudson H. T.
Published: March 2005

Sixty students in a second semester freshman physics class were administered a test of formal operational reasoning. The composite logical test score was correlated with students’ final examination grades and yielded a correlation of 0.49. Furthermore, the composite correlation distribution provided evidence that the ability to employ formal operational reasoning is a necessary, though not sufficient, condition for student success in physics. These results point to the importance of seriously considering including, within the framework of physics courses, interactions and experiences designed to develop logical reasoning.
Simulation of quantum-mechanical measurements with programmable pocket calculators
Authors: Sauer G.
Published: March 2005

A method for the illustration of the statistical nature of measurements in quantum physics by means of simulation with pocket calculators is described. The application to examples like the double-slit experiment, Mott scattering, and the demonstration of the uncertainty relation is discussed.
Variations on the hydrogen atom: The generator coordinate method
Authors: Chen Hsi-Tseng , Piza A. F. R. de Toledo
Published: March 2005

A nonorthogonal expansion applied to the hydrogen atom is proposed as a pedagogical introduction to the ideas of the generator coordinate method. It can be discussed in any introductory course on quantum mechanics and provides for good numerical approximations at very low computational cost.
Simple experiment for studying the properties of a ferromagnetic material
Authors: Sood B. R. , Kamal R. , Sikri S.
Published: March 2005

A simple experimental set up is described for studying Curie temperature TC, temperature dependence of permeability in the vicinity of TC, and Curie constant of a ferromagnetic material. The setup has been used to study these parameters for nickel. Using these parameters an estimate of the exchange field has been made.
Multiple lens experiment
Authors: Waring Richard C.
Published: March 2005

The experiment described herein makes use of a number of concepts from geometrical optics including definition of the focal length of a thin lens, reflection by a plane mirror, thin lenses in contact, and the lens maker’s equation. The experiment requires very inexpensive components and is suitable for students in elementary college physics classes.
Sound analyzer as an undergraduate laboratory tool
Authors: Nave C. R. , Garland B. D.
Published: March 2005

Several interesting laboratory experiments in acoustics can be built around a sound analyzer and a storage oscilloscope. The Tektronix 5L4N Spectrum Analyzer has been used for several experiments in a course entitled ’’The Physics of Music and Speech,’’ as well as for undergraduate research projects and some projects carried out in cooperation with local high schools. The experiments described involve the analysis of speech and musical instrument sounds and the general analysis of the frequency range of complex sounds.
Quantal tunneling through a rectangular barrier using ‖ ψ ‖2 and flux
Authors: Draper James E.
Published: March 2005

The transmission coefficient for quantal tunneling through a rectangular, one-dimensional potential barrier is analyzed. By employing continuity of ‖ ψ ‖2 and flux the results, even with an asymmetrical barrier, are obtained easily. The asymmetrical barrier has the same transmission in either direction. Considerable insight into the form of the most physical quantity, ‖ ψ(x) ‖2, is afforded with little algebra. Graphs of transmission are given for general barriers, and properties of the solutions are discussed.
A simple application of adiabatic invariance
Authors: Gleiser R. J. , Kozameh C. N.
Published: March 2005

The method of the adiabatic invariants is used to study the motion of a test particle in the field close to a self-gravitating, spherically symmetric shell of dust. It is shown that the particle behaves as if under the action of a force that tries to keep it bounded to the shell, although there is no force on the particle when it is inside the shell. This effect is analyzed from the points of view of both an inertial observer and of an observer at rest on the shell. In the latter case ’’inertial forces’’ must be taken into account and so the problem can be used to illustrate the importance of this concept in noninertial frames of reference.
Graphical approach to Fresnel’s equations for reflection and refraction of light
Authors: Doyle William T.
Published: March 2005

A coordinate-free approach to Fresnel’s equations is developed. The method applies to arbitrary transparent media, with light of either s or p polarization, at any angle of incidence. A graphical construction is described for finding the vector amplitudes of the reflected and transmitted waves. Total internal reflection and Brewster’s Law have a simple graphical interpretation.
Microwave propagation in dielectric fluids
Authors: Lonc W. P.
Published: March 2005

An undergraduate experiment designed to verify quantitatively the effect of a dielectric fluid’s dielectric constant on the observed wavelength of microwave radiation propagating through the fluid is described. The fluid is castor oil, and the results agree with the expected behavior within 5%, assuming a dielectric constant of 2.65±0.05 for castor oil at 3-cm wavelength.
Is the isotropy of the speed of light a convention?
Authors: Fung Shing-Fai , Hsieh K. C.
Published: March 2005

Some philosophers have asserted that the speed of light in any one direction cannot be measured and that Einstein’s postulate on the constancy of the speed of light remains a convention. By examining two thought experiments, we conclude that one-way speed of light can be measured and that Einstein’s postulate can be tested.
Analysis of a pseudostationary wave
Authors: Gabrielli I. , Zugna S.
Published: March 2005

The characteristics of a progressive and a stationary plane wave (of any kind) are well known, as well as the equivalence of the latter to two superposed antiparallel beams of equal amplitude. The purpose of this paper is to present the fundamental feature of a ’’pseudostationary’’ wave corresponding to the superposition of two antiparallel beams of different amplitude and to analyze the dynamic properties of such a wave.
Speed(s)
Authors: Lévy-Leblond Jean-Marc
Published: March 2005

Three simple distinct operational procedures are given for transforming the empirical notion of speed into a formal concept. While in the Galilean theory of space-time, the three quantities coincide with the customary velocity, they differ in the Einsteinian theory. In particular, it is shown that ’’rapidity’’ has a direct and natural physical meaning.
Entropic approach to Brownian movement
Authors: Neumann Richard M.
Published: March 2005

A diffusional driving force, called the radial force, which is responsible for the increase with time of the scalar separation between a fixed point and a particle undergoing three-dimensional Brownian motion, is derived using Boltzmann’s equation. The radial force is used to derive several results from the classical theory of Brownian motion, namely Einstein’s 〈x2〉 = 2Dt equation and the expression for the one-dimensional harmonic oscillator. The radial force concept is then extended to establish a thermodynamic criterion for the occurrence of a melting transition in a liquid whose particles attract one another by means of centrally symmetric forces. The theory, when applied to the alkali halide and alkaline-earth oxide molten salts, accurately predicts the observed melting temperatures. The definition of the dielectric constant used in the ionic salt fusion theory also provides a basis for understanding molten salt surface tensions. Finally, the radial force is used to demonstrate that an ideal rubber network is not prone to collapse into a state having zero volume.
Experiment on the vibration of a plate
Authors: Kautz Allan D.
Published: March 2005

An experimental setup is described which will allow one to study the resonance characteristics of a vibrating plate. One can determine the resonance frequency, damping coefficient, and quality factor, obtain the resonance curve, measure the vibration amplitude, and demonstrate nonlinear behavior. The methods are demonstrated using a small, circular steel plate clamped around its periphery. Much of the output is obtained graphically, which should enable the student to gain a more thorough understanding of the phenomena.
Linear programming applied to a simple circuit
Authors: Boyd J. N. , Raychowdhury P. N.
Published: March 2005

There exist few applications of linear programming in physics, particularly on the instructional level. Therefore we provide a discussion suitable for the physics classroom. Basic ideas in linear programming are presented and illustrated with simple examples. The techniques of linear programming are applied to the analysis of a circuit designed to charge batteries connected in parallel. Lastly, the simplex method for the solution of linear programs is briefly discussed.
Euler’s three-body problem
Authors: Wild Walter J.
Published: March 2005

The simplest three-body problem that attracts physical interest is the one first studied by Euler. In Euler’s problem, a primary and secondary mass are fixed in space, a given distance apart, and a test mass is allowed to move unrestricted in their superimposed gravitational fields. The equations of motion are derived and solved via a simple numerical procedure. The algorithm is adaptable to a small programmable calculator and should help to stimulate interest in the classroom. Several examples of motion are discussed and graphically presented.
Pocket calculator program for least-square fitting of data with variable precision
Authors: Picot A.
Published: March 2005

Computation of a line by the least-square-fitting method is possible with many pocket calculators. But it is generally not realized that commerically available programs do not take into account with the precision of the experimental points and consequently the line obtained is not correct. We present the calculation including this factor in the most general case. The method is exemplified with a classical student experiment: the optimization with an HP25 calculator of the decay period of 110Ag.
Deceptively simple harmonic motion: A mass on a spiral spring
Authors: McDonald F. Alan
Published: March 2005

The oscillatory motion of a mass on a spiral (nonhelical) spring is shown to have a closed-form solution in terms of Bessel functions of order 2/3. The lowest eigenfrequency and the associated effective spring mass are calculated for a range of values of the attached mass. Analytic and numerical comparisons are made to the helical spring problem.
Self-paced freshman physics laboratory and student assessment
Authors: Patterson J. R. , Prescott J. R.
Published: March 2005

Laboratory work is included as an essential part of any physics course because it teaches the student aspects of physics that are distinct from lecture material and that can be learned in no other way. For the same reason it presents its own problems in assessment, particularly in large first-year university classes. For the last five years we have been putting into practice a form of self-paced laboratory experience and assessment. The laboratory is design oriented. The grade for the course is determined by the aggregation of point values for a variable number of experiments completed in a fixed period of time to a satisfactory standard. The marks feature a degree of discrimination comparable to written theory examinations. Within the limits imposed by class size, the student has a fair degree of freedom of choice.
Resource letter NP-1: New particles
Authors: Rosner Jonathan L.
Published: March 2005

The growth in the number of ’’elementary’’ particles since the discovery of the J/ψ in November of 1974 is reviewed. An attempt is made to combine references to initial discoveries, to reviews of theory and experiment, and to elementary discussions in a way that may be useful at a wide variety of levels. Accordingly references are marked E (Elementary), I (intermediate), and A (advanced). Articles selected for incorporation in a reprint volume (to be published separately by the American Association of Physics Teachers) are marked (‡). For a shorter list of particularly helpful elementary and intermediate references, the reader may consult those marked with an asterisk (*).
Image-space method for a classroom analysis of the diffraction patterns
Authors: De Micheli R.
Published: March 2005

A simple method is described: to form on a large fixed screen the succession of the diffraction patterns on the different planes of the diffracted field, from the aperture to infinity. The method is based on the packing effect of a lens which images the entire diffracted field in a few centimeters. A theoretical analysis of the diffraction field in an image space is given, together with some illustrative pictures.
Experience with a professionally oriented astronomy laboratory for nonscience majors
Authors: Annett Clarence H.
Published: March 2005

The laboratory to accompany a one-semester descriptive astronomy course has been redesigned. Standard topics are retained, but the orientation is changed to introduce the nonscience major to the work of the professional astronomer. Student needs are met by building the laboratory around a solid foundation of astronomical observation. Several semesters of use indicate good success as measured by increased enrollment and positive student feedback.
Goals, aspirations, and attitudes of MIT undergraduate physics students
Authors: Senator Ted E.
Published: March 2005

A survey of undergraduate physics students at the Massachusetts Institute of Technology was conducted in order to ascertain their career goals, their perceptions of the manpower situation in physics, and their reasons for choosing to study physics. Most of these students intend to receive a Ph.D. in physics and would prefer a career in a traditional employment sector for physicists, namely, research and teaching in a university, or research in an industrial or government laboratory. They believe that everyone who desires employment as a physicist will not be able to attain his goal. They are studying physics because they find it interesting, not because they expect it to be valuable in their future employment. A significant fraction are studying physics as a preparation for further study and/or a career in another field.
Comment on ’’Ballistics of the modern-working recurve bow and arrow’’
Authors: Marlow W. C.
Published: March 2005

The author makes a comment on the evaluation of the kinetic energy of a bow string for the recurve bow.(AIP)
Zero-point term in cavity radiation
Authors: Jiménez José Luis , de la Peña L. , Brody T. A.
Published: March 2005

We show that if one accepts the reality of a zero-point term (1/2)h/ω per normal mode in the spectral distribution of cavity radiation, then the Planck law can be derived with no further nonclassical assumptions; we do this in two different ways, both based on Einstein’s work at the beginning of the century. The argument is intuitive and clarifies some conceptual difficulties; we point out where more elaborate theoretical work is required. A related derivation of the Planck law due to Boyer is examined.
If Maxwell had worked between Ampère and Faraday: An historical fable with a pedagogical moral
Authors: Jammer Max , Stachel John
Published: March 2005

If one drops the Faraday induction term from Maxwell’s equations, they become exactly Galilei invariant. This suggests that if Maxwell had worked between Ampère and Faraday, he could have developed this Galilei-invariant electromagnetic theory so that Faraday’s discovery would have confronted physicists with the dilemma: give up the Galileian relativity principle for electromagnetism (ether hypothesis), or modify it (special relativity). This suggests a new pedagogical approach to electromagnetic theory, in which the displacement current and the Galileian relativity principle are introduced before the induction term is discussed.
Interaction of a charge and an electric dipole in one dimension
Authors: Lapidus I. Richard
Published: March 2005

The quantum-mechanical interaction of an electric charge and an electric dipole in one dimension is investigated using the delta-function potential to represent the interaction between charges. It is found that there is a single bound state. The problem of scattering of a charge from an electric dipole is solved exactly and in Born approximation. Because the potential is not symmetric, a phase shift analysis does not yield the correct cross section.
Integrated applied programs in physical sciences
Authors: Byrd J. William
Published: March 2005

The high degree of specialization prevalent in the traditional education of contemporary physicists has worked to the detriment of the profession on occasion in recent history. Many careers have been salvaged by switching fields and adapting basic training already acquired to fruitful pursuits in other areas. Such broadening might well be a part of the educational process, but it will require alternative structures in curriculum programming. Data gathered in a national survey are presented which support the case for a physical scientist broadly educated in applied areas. The paper argues that physical scientists should compete for a larger share of the industrial job market; however, the competition will require flexibility in program packaging and some shifting of the types of educational experiences made available to students.
Some nonexplanations of bicycle stability
Authors: Kirshner Daniel
Published: March 2005

In this paper we attempt to verify a nongyroscopic theory of bicycle stability, and fail.
Contour plots using a moiré technique
Authors: Marsh James S.
Published: March 2005

A simple method utilizing a moiré technique for producing contour plots is described and applied to the rendering of calculated Fraunhofer diffraction patterns.
Spectroscopy with supersonic jets
Authors: Skinner Anne R. , Chandler Dean W.
Published: March 2005

Supersonic jet spectroscopy presents a way of studying extremely cold gas phase molecules without cryogenic apparatus. The spectra of cold molecules are generally easier to interpret than those of the same molecules at room temperature, thus facilitating the determination of molecular structure. Cooling also makes it possible to study weakly bound species such as van der Waals complexes. In addition, this technique is an interesting example of applications of gas kinetic theory. The paper discusses both the theory of supersonic jets and a typical experimental example.
A problem and its solution involving Maxwell’s equations and an inhomogeneous medium
Authors: Williamson W.
Published: March 2005

Maxwell’s equation are solved for an inhomogeneous medium which has a coordinate-dependent dielectric function. The problem and its solution are given in a format which should make it useful as an intermediate or advanced level problem in an electrodynamics course.
Electrostatic image problems with plane boundaries
Authors: Terras Riho , Swanson Robert A.
Published: March 2005

We consider the electrostatic problem of a point charge in a domain bounded by conducting planes. We list all such domains for which a solution by images exists, describe the image charge arrays in familiar crystallographic terms, and give an illustrative example. We also give an account of the methods used to arrive at the allowed domains and their corresponding solutions.
Interference colors with ’’hidden’’ polarizers
Authors: Silverman Mark P.
Published: March 2005

The author demonstrates the importance of polarizers when investigating interference colors in birefringence by considering a special case of cellophane placed on a smooth kitchen table illuminated from behind by an open window.(AIP)
Response by the Oersted medalist: Autonomy and input
Authors: Karplus Robert
Published: March 2005

I believe that people become vitally interested in their studies and learn best when direction and guidance from a source of authority are combined with ample opportunities for the students to direct and control their own learning. The former may be called instructional input, the latter student autonomy. Hence the phrase ’’autonomy and input’’ characterizes a teaching program that balances these two factors. Yet one must also consider the relation between these two elements. They may be uncoordinated as in a physics course with lectures (input) and concurrent but independent open laboratories (student autonomy). Alternatively, the course might provide for more interaction between the two elements when the lectures (input) respond to questions or issues raised during previous investigations (autonomy) and follow-up investigations provide for applications of the new material.
Gauge invariance and hidden symmetries
Authors: Moriyasu K.
Published: March 2005

We present a simple introduction to the basic physical ideas involved in the flux quantization number carried by systems such as magnetic monopoles and vortices. By using simple geometrical arguments, we see that the flux number is associated with a hidden symmetry in gauge theory that is topological in origin.
The pendulum reborn: Time measurements in the teaching laboratory
Authors: Bazin Maurice , Lucie Pierre
Published: March 2005

To oppose the trend towards a formal, purely theoretical teaching of physics we present our first practical step at creating a lively laboratory practice at the first-year university physics level in Brazil. Two pendula are used simultaneously as the system under study and the time measuring reference instrument. We describe how we integrate historical and cultural references within our laboratory practice.
Hydrogenlike atom in the potential V = r2(a+b cos2θ): Second-order perturbation theory
Authors: Dasgupta Basab B.
Published: March 2005

We report a calculation of the ground-state energy of a hydrogenlike atom in an external potential given by V = r2(a+b cos2ϑ), using the second-order perturbation theory. The matrix elements, involving both the bound-state and continuum-state eigenfunctions, are explicitly evaluated. Implication of the result in the magnetic study of quasi-two-dimensional electron layers on a liquid-helium surface is discussed.
Surface properties of Kerr–Newman black holes
Authors: Doughty Noel A.
Published: March 2005

The magnitude of the proper acceleration of a stationary observer in the exterior Kerr–Newman geometry is used to determine an elementary property of the event horizon of a rotating charged black hole and to give a simple physical interpretation of its ’’surface gravity’’ as used in descriptions of the Hawking radiation. The global (nonlocal) nature of a black hole event horizon is also simply illustrated. The Kerr–Newman metric and the calculations based on it are presented in SI equations for the benefit of the many students and teachers in physics who rarely use any other system. To minimize the mathematical tools required we carry out the calculations in the well-understood Boyer–Lindquist coordinates.
Hall effect in a plasma
Authors: Kunkel W. B.
Published: March 2005

In low-density plasmas, such as the positive columns of glow discharges, the Hall effect is very large and easily observable. An elementary analysis, reproduced here, shows that the Hall voltage between opposite sides of such a column measures only half of that expected ideally in a conductor with the same carrier density. The reduction is caused by ambipolar diffusion of the carriers whose density distribution is distorted in the presence of a transverse magnetic field. A simple experimental arrangement is described in which the Hall voltage across a helium discharge column is determined as a function of magnetic field, discharge current, and gas pressure. Thus electron drift velocity and density are inferred. A simultaneous measurement of the resistivity then permits evaluation of the collision frequency. If the collision cross section for scattering of electrons by helium atoms is given, the electron temperature can be estimated. Variation of the parameters thus permits a study of the scaling laws for the glow discharge column. The experiment is found to be a very rewarding educational experience.
Illustrating gauge invariance in quantum mechanics through the free electron in a uniform time-varying electric field
Authors: Leubner C.
Published: March 2005

The nature of gauge transformations and gauge invariance in quantum mechanics about which there exists so much confusion in the literature is simply and pedagogically illuminated by first carefully investigating in various gauges the elementary problem of a free electron subject to a spatially uniform time-dependent electric field, and by then utilizing the findings from this particular example to clarify some general misconceptions.
Introduction to sampling theory via low-cost transient recorder
Authors: Basano L. , Ottonello P.
Published: March 2005

An application of solid-state memories in a laboratory course is described which can achieve a two-fold goal. First, it enables students to build devices that are commercially sold at much higher prices; second, it offers an opportunity to introduce the fundamentals of analog-to-digital conversion and sampling theory in a very practical way. Both aspects are discussed.
Model bandstructure calculations
Authors: Bahurmuz A. A. , Loly P. D.
Published: March 2005

Simple method for bandstructure calculations is presented to bridge the gap between textbook treatments and research calculations. The method is based on the multiple scattering of electrons in periodic potentials and can be applied in a straighforward way to obtain the essential features of electronic bandstructures in one, two, and three dimensions. In the one-dimensional case the method is applied to the Kronig–Penney model and the results compared with other methods. Extensions to two and three dimensions are also presented.
Note on the analogy between inertial and electromagnetic forces
Authors: Semon Mark D. , Schmieg Glenn M.
Published: March 2005

The authors point out that the inertial force F3 = −mω×r is completely analogous to the force associated with an induced emf. (AIP)
Negative acceleration components for a relativistic particle
Authors: Lock J. A.
Published: March 2005

Newtonian acceleration is considered in the light of special relativity theory with the result that the component of acceleration in the direction of an arbitrary applied force is always positive.(AIP)
Comment on ’’Detonation in miniature’’
Authors: Zinman Walter G.
Published: March 2005

The ZND model of the steady detonation waves as outlined by Fickett is refuted on the grounds that it does not represent a complete picture of reality.(AIP)
Astronomical precession: A good and a bad first-order approximation
Authors: Haisch Bernhard M.
Published: March 2005

The problem of calculating the precession of the equinoxes due to the torque of the sun and moon on the Earth is often cited in mechanics texts as a classic example of the behavior of a heavy symmetrical top. Unfortunately this problem is often alluded to but seldom solved. A simple equatorial band model for the Earth and smeared out mass distributions for the sun and moon are used herein to solve this problem. It is found that one intuitively apparent approximation for the gravitational force on the band results in a precession period that is too long by a factor of 3/2, whereas a slightly more sophisticated approach provides an answer good to better than one percent.
Psychophysical basis for consonant musical intervals
Authors: Resnick L.
Published: March 2005

A suggestion is made to explain the acceptance of certain musical intervals as consonant and others as dissonant. The proposed explanation involves the relation between the time required to perceive a definite pitch and the period of a complex tone. If the former time is greater than the latter, the tone is consonant; otherwise it is dissonant. A quantitative examination leads to agreement with empirical data.
Gauge-invariant classical Hamiltonian formulation of the electrodynamics of nonrelativistic particles
Authors: Kobe Donald H.
Published: March 2005

The Hamiltonian formalism for nonrelativistic charged particles in an electromagnetic field is shown to be manifestly gauge invariant. The Hamiltonian for the subsystem consisting of the interacting particles is shown to be form invariant under gauge transformation, but numerically dependent on the choice of gauge. The energy, which is numerically the same in all gauges, is obtained by subtracting the scalar potential of the time-dependent radiation field from the Hamiltonian. The time rate of change of the energy of the particles is equal to the Joule power, which is the power lost by the field, so that energy of the entire isolated system consisting of particles and radiation field is conserved. In the quasistatic approximation, the energy of the longitudinal electric field gives the instantaneous Coulomb interaction energy, which can be associated with the particles.
Momentum-space derivation of the Runge–Lenz vector
Authors: Patera Russell P.
Published: March 2005

Momentum-space theory is used to derive the Runge–Lenz vector. This very simple derivation unites the Runge–Lenz vector theory and the momentum-space theory.
Domestic fire and its improvement: Some qualitative insights
Authors: Cranberg Lawrence
Published: March 2005

The author is concerned with a qualitative formulation in terms of the general principles of heat transfer, and the roles played by conduction, convection, and radiation seperately and by interaction with each other in the context of the domestic wood fire. (AIP)
Experimental ’’paradox’’ in electrodynamics
Authors: Klein W.
Published: March 2005

The formulation and solution of a problem in electromagnetic theory is presented.(AIP)
Reversible energy converter
Authors: Barford N. C.
Published: March 2005

A device for illustrating the reversible conversion of thermal energy to mechanical work is discussed theoretically and quantitative design parameters are given for constructing a laboratory scale model. Preliminary results show that avoidance of frictional forces does enable operation of the device closely to approach reversibility. Suggestions are made for further exploitation of the principles involved.
Towards an impressionist picture of the history of astronomy
Authors: Celnikier L. M.
Published: March 2005

A description and short extract are given of a tabulated history of astronomy, in which particular emphasis is placed on the interaction of astronomy with various discilplines.
Listening to the Doppler shift of visible light
Authors: Crandall R. E. , Wishnow E. H.
Published: March 2005

Doppler shift of light can be reproduced audibly with minimal apparatus: a commercial He–Ne laser, two mirrors, a photodetector, and a stereo amplifier with speakers. A dual-trace oscilloscope and signal generator can be added to obtain a numerical value for the laser wavelength. The method can be extended to display optical spectra directly on an audio spectrum analyzer.
Teaching kinematics with electronic equipment
Authors: Fernández J. Maria Vega , Bernal J. José Peña , Bueno M. Angeles Rossell , Delgado Manuel Gálvez , Balsera Benito Mahedero
Published: March 2005

A method is presented for teaching some topics of kinematics. It involves the use of electronic equipment, which allows active student participation, the systematic analysis and solution of problems, and the use of a quick feedback loop for training.
Some remarks on a generalized heat conduction equation
Authors: Agarwal V. K.
Published: March 2005

The author makes some remars on the theory of heat conducted in solids.. (AIP)