bluuebunny/crossref_metadata_2025 huggingface dataset:
Motion of a Relativistic Particle Acted Upon by a Constant Force and a Uniform Gravitational Field
Authors: Lapidus I. Richard
Published: August 2005

The complete two-dimensional solutions for the relativistic motion of a particle acted upon by a constant force and a uniform gravitational field are obtained. The gravitational force is velocity dependent as a consequence of the equivalence of inertial and gravitational mass. The solution for the special case of one-dimensional vertical motion is also obtained.
Percentage Contour Maps of Electron Densities in Atoms
Authors: Gerhold George A. , McMurchie Larry , Tye Timothy
Published: August 2005

Monte Carlo calculations are used to generate contour maps of atomic orbitals in which the contours enclose specified percentages of the total electron density. Maps for the most common atomic orbitals are presented, and recommendations for the presentation of atomic orbitals are made.
Confocal Conic Sections as Interference Patterns
Authors: Andrews C. L. , Carpenter C. R.
Published: August 2005

A uniform treatment of the basic interference patterns as conic sections is presented by construction methods. In the course of this treatment two general theorems were evolved: (1) If two traveling waves are superposed to form an interference pattern and if the direction of travel of one of the waves is reversed, the new interference pattern is orthogonal to the first. (2) The shortest distance between two maxima of irradiance in any interference pattern is a half-wavelength. The methods of producing these two-dimensional patterns and related three-dimensional patterns are indicated.
The Early History of the Titius-Bode Law
Authors: Jaki Stanley L.
Published: August 2005

In its original form the Titius-Bode law appeared under Bonnet's name in 1766. In 1772 Titius identified himself as the author of the law, but in the same year Bode borrowed under his own name Titius' formulation of the law. Titius attributed the law, wholly arbitrarily, to Bonnet, Lambert, and Wolff. From 1772 until 1787 Bode was practically alone among astronomers to mention the law in its primitive, sequential form, in his various writings. The algebraic, functional form of the law was given by Wurm in 1787. The distance of Uranus, discovered in 1781, fitted well into the law which inspired the search for the missing planet between Mars and Jupiter. The discovery of Ceres in 1801 was a triumph of the law only until the discovery of Pallas in 1802, which produced the opposite effect. Most leading astronomers of the period considered the law as a mere game with numbers.
Propagation of a General Disturbance along a Semi-Infinite Linear Chain
Authors: Lee K. H.
Published: August 2005

Propagation of a general longitudinal disturbance along a semi-infinite linear chain made of identical particles and identical massless springs is studied. Initially, all the particles except the end particle are at rest, and all the springs except the first one are at equilibrium length. The Laplace transform method is used to express the subsequent motion of all the particles when the displacement of the end particle is given as an arbitrary function of time. The external force to be applied on the end particle to achieve such a motion is also expressed in terms of the displacement of the end particle. The present results include the results obtained and discussed by Morse and Ingard, Weinstock, and Baroody and Drauglis for a uniform motion of the end particle as a special case.
Physics in Undergraduate Engineering Education— Report of a Survey
Authors: Alley Reuben E.
Published: August 2005

A questionnaire addressed to physics department chairmen and engineering deans in the 213 accredited engineering colleges in the United States and Canada brought replies from 132 institutions. These provided factual information about course requirements and content, and statements of opinion regarding such subjects as the effectiveness of the physics courses and laboratories, the existence of unnecessary duplication in the engineering curriculum, and problems of communication between physics and engineering departments. Replies from selected junior colleges provided information on course content and relations with senior colleges.
Fourier Transform Spectroscopy Using a Michelson Interferometer
Authors: Albergotti J. C.
Published: August 2005

The use of the Michelson interferometer as a Fourier transform spectrometer is described. Fringe visibility curves are obtained with an electron photomultiplier or silicon photocell, and Fourier transforms of the visibility curves are taken with the aid of a digital computer. Application of the technique is made to the axial mode structure and phenomenon of “hole burning” in He-Ne lasers, to the shape of the mercury green line and sodium yellow lines, and to the Zeeman spectrum of the mercury green line Δmj = 0 transitions.
Analysis of Low-Temperature Heat Capacity Data
Authors: Weir R. D.
Published: August 2005

This paper is tutorial and discusses how analysis of low-temperature heat capacity data for simpler crystalline solids can be carried out. The lattice heat capacity is considered in relation to the vibrational properties of the solid. Emphasis is given to the physical interpretation of the various derived quantities and to the meaningful limits to which the data can be extended.
The Copenhagen Interpretation
Authors: Stapp Henry Pierce
Published: August 2005

An attempt is made to give a coherent account of the logical essence of the Copenhagen interpretation of quantum theory. The central point is that quantum theory is fundamentally pragmatic, but nonetheless complete. The principal difficulty in understanding quantum theory lies in the fact that its completeness is incompatible with external existence of the space-time continuum of classical physics.
On the Doppler Effect
Authors: Ram B.
Published: August 2005

Expressions for the Doppler effect are derived without employing any assumption about the phase of a plane wave. It is shown that the invariance of this phase under both the Galilean and the Lorentz transformations is a trivial consequence of the mathematics and, is independent of its association with any physical process.
A Physicist's Introduction to Bayesian Statistics. II
Authors: Raeside D. E.
Published: August 2005

This sequel to an earlier paper applies Bayesian estimation theory to several probability distributions of importance in physics [Poisson, Maxwell, Rayleigh, exponential, Druyvesteyn, and Gauss (zero mean) distributions]. A single tractable and physically interesting loss function (the square of the relative estimation error) is utilized. Bayes estimates are obtained by using a single conjugate prior distribution (the gamma distribution) and the vague prior limit is taken. The estimates obtained tend to the mean values of the respective posterior distributions for large sample sizes. A practical aspect of the theory is demonstrated by obtaining an optimal estimate of the most probable speed for a Maxwell distribution of speeds.
Percolation Processes and Cooperative Phenomena
Authors: Scott H. L.
Published: August 2005

A random lattice may be defined by constructing an empty grid, and then placing particles on the sites (or bonds) randomly, with some definite concentration p. Under certain conditions, a process called percolation may take place in such systems. In this article we wish to acquaint the readers of this Journal with percolation theory, and to show that such processes provide a qualitative mechanism for the onset of order in a cooperative system.
The Bohr-Sommerfeld Theory and the Uncertainty Principle
Authors: Beers Yardley
Published: August 2005

It is suggested that, if the Wilson-Sommerfeld quantization postulate is modified such that phase integrals for nonignorable coordinates are placed equal to half-integers times Planck's constant while those for ignorable coordinates are placed equal to integers times Planck's constant, eigenvalues that are in much better agreement with quantum mechanics are obtained. Also there results a picture of the radiation process that is conceptually consistant with classical theory. It avoids the picture of an electron making many revolutions in a closed orbit without radiating. Some of the discussion is based upon developments in classical theory that have evolved since the Bohr-Sommerfeld theory was formulated. In addition, some of the effects of the uncertainty principle are made more apparent.
Nuclear Quadrupole Resonance in Solid Nitrogen— An Exercise in Quantum Mechanics
Authors: McEnnan M. M. , Scott T. A.
Published: August 2005

The field of nuclear quadrupole resonance (NQR) in molecular solids provides a rich new source of instructive, easily varied, workable problems in quantum mechanics. Examples which cover the subject areas of spin, identical versus distinguishable particles, degenerate bound-state perturbation theory, symmetry properties of operators and wavefunctions, and selection rules are presented in an integrated discussion of a current research problem involving NQR of N (I = 1)14 in solid α-N2 enriched in the N15 isotope (I = 12). In this solid, the nuclear quadrupole moments interact with an axially symmetric electric field gradient (EFG), and, to an excellent approximation, each diatomic molecule can be treated as a separate two-spin system in which the nuclear quadrupole energy levels are perturbed by a coupling between the magnetic moments of the nuclei. Spectra obtained from first-order perturbation theory applied to both N14-N14 and N14-N15 molecules are compared with the results of an exact calculation and with experiment. In addition, it is demonstrated simply that in the presence of an asymmetric EFG the dipolar interaction of a spin-1 nucleus with a spin-12 nucleus is completely quenched to first order, while some splitting remains for the spin-1-spin-1 case.
Signal Averaging at Modest Cost
Authors: Hudgings Daniel W. , Dragt Alex J.
Published: August 2005

We describe how to perform signal averaging using a multichannel analyzer without internal modification. It thus becomes possible to average signals with the aid of “borrowed” equipment. Required equipment, in addition to a multichannel analyzer, consists of approximately $100 worth of transistor circuitry and a voltage to frequency converter.
A Simple Approach for the Calculation of Energy Levels of Light Atoms
Authors: Woodyard Jack R.
Published: August 2005

Considerable insight into elementary atomic theory is generated by constraining the atomic Hamiltonian of atoms with few electrons by demanding that the electrons be as far apart as possible. This and other simplifying assumptions allow us to separate Schrödinger's equation by reducing the problem to a geometrical analog. The analogous problem is to locate dots symmetrically on the surfaces of concentric spheres consistently with the Pauli principle and with the dots as far apart as possible. The resulting equations permit calculation of effective nuclear charges which are used to find the total energy of the system from a hydrogenlike energy formula. The energies so determined are compared to experimental values, and derived screening terms are compared to those of Slater's rules. Our energies are consistently lower than experimental values. Several unanswered questions opened by this technique are proposed as possible further research on a level suitable for an undergraduate paper.
The Resistive Net and Finite-Difference Equations
Authors: Lavatelli Leo
Published: August 2005

The application of finite-difference equations in the solution of repetitive multiloop resistive circuits in one-and two-dimensional configurations is discussed in both finite and infinite cases. The technique of solution involves only ordinary algebra and trigonometry. Yet one can see the emergence of simple orthogonal functions and the finite-difference approximations of the Cauchy-Riemann equations and Laplace's equation. Boundary-value problems can be presented and understood at a simple level of physics and mathematics. Such repetitive structures can serve as discrete approximative models for various physical properties of continuous media. The implications for the teaching of boundary-value problems in electricity are brought out.
Energy Quantization and the Simple Harmonic Oscillator
Authors: Swenson R. J. , Hermanson J. C.
Published: August 2005

Two methods for obtaining the ladder spectrum characteristic of the simple harmonic oscillator are widely used in elementary quantum mechanics. In the first method, that of series solution, quantization is shown to follow from the requirement that the wave function be normalizable. In the second, it is common to derive quantisation in an operator formalism based on factorization of the wave equation. In this latter method the role of normalizability is not customarily discussed. We show explicitly that the same boundary condition implicit in the operator manipulations leads to quantization in both methods.
A Unique MS Program for Graduates of Four-Year Colleges
Authors: Loper G. D. , Breazeale J. B. , Unruh H.
Published: August 2005

A large and increasing gap exists between the level and sophistication of the physics encountered by a student in his undergraduate work at a four-year college with no graduate program and the level and sophistication of the physics with which he must work in the PhD program of a large university. In order to help bridge this gap, Wichita State University designed an MS program especially for graduates of four-year colleges, with the intention of preparing them for PhD study at larger universities. This article describes the workings and results of the program and gives some insight into the planning of students for their careers in physics.
A Computer Simulation for the Study of Waves
Authors: Bork Alfred M. , Robson John
Published: August 2005

The computer program described, designed for use in the second quarter of the beginning course for science and engineering majors at the University of California, Irvine, simulates an experimental investigation of a pulse in a rope. The student is provided with a “measurement” facility: If he enters time and position he is told the rope displacement. His problem is to discover enough about the disturbance to answer numerical questions about its behavior. Auxiliary facilities such as plotting and listing are provided. Checks are made as to the reasonableness of the student strategy, and suggestions are given based on these checks. It is hoped that through this simulation students can in many cases “discover” the preservation of “shape,” the x−vt dependence of the pulse.
Open-Ending a Senior Modern Physics Laboratory
Authors: Finegold Leonard
Published: August 2005

Many students, especially good theoretically inclined ones, dislike laboratory courses. There is often financial pressure to reduce laboratory courses, which are expensive on a student credit-hour basis. This paper describes an effort to increase the flexibility of a senior modern physics laboratory, which is well equipped, by eliminating rigid scheduling, giving students choice of experiments, and allowing them to do experiments in depth. Student motivation, interest, and learning were considerably increased. A brief description of the laboratory is given, together with details of some new experiments and recommended books.
Laser-Excited Raman Spectroscopy
Authors: Edwards David F. , She C. Y.
Published: August 2005

The cw gas laser used as the excitation source has been responsible for great changes in Raman spectroscopy. An introduction to laser-excited Raman spectroscopy is presented with the purpose being to minimize mathematical formalism and to provide a physical insight into the techniques.
C
14
Dating with Nuclear Track Emulsions
Authors: Jeffreys Danny , Larson Duane , French John D.
Published: August 2005

A C14 dating procedure employing nuclear emulsions is described. The attributes of modest cost, no need for electronic circuits, and interdisciplinary nature suggest that it is suitable for undergraduate research participation. The sensitivity is such that less than 0.2-g carbon samples can be assayed, providing an area of application avoided by counter methods.
Classical Theory of Optical Dispersion
Authors: Christy R. W.
Published: August 2005

Classically the complex dielectric constant of a material is calculated as a function of the frequency of light by treating the electrons and ions as harmonic oscillators or free particles. Since the result is formally the same as quantum results, it has considerable practical usefulness. The complex refractive index determines the propagation of light in the medium and its reflection at a free surface. Dispersion is always associated with absorption, but the details of the frequency dependence of the optical constants vary rather widely with the kind of material. All the limiting cases are discussed separately. Relations such as those of Kramers-Kronig and Lyddane-Sachs-Teller follow easily from the model. The results are applied to some examples in real solid materials.
Exponential Decay With a Memory
Authors: Robiscoe R. T. , Hermanson J. C.
Published: August 2005

We examine the exponential decay law for an excited quantum system in the case where the state amplitude has a “memory,” that is, where the rate at which the amplitude is decaying at a particular time depends to some extent on values of the amplitude at previous times. For a particular choice of memory, characterized by a memory time τ, the amplitude obeys the differential equation of a damped harmonic oscillator. When τ is greater than a certain critical memory time τc, comparable to the natural lifetime of the state, the amplitude becomes an exponentially damped oscillation in time. When τ is less than τc, the decay is nearly exponential with a decay rate somewhat greater than that calculated from standard theory. By comparing theory with experiment, we can place an upper limit on the memory time for the radiative decay of atoms.
Factorization Types and SU(1, 1)
Authors: Carlstone D. S.
Published: August 2005

For a particular form of the radial Schrödinger equation it is possible to define SU(1, 1) as a noninvariance group. From the SU(1, 1) algebra and the properties of the unitary irreducible representations, one can easily find the energy eigenvalues. It is observed that the equation is essentially the standard form of the C-type factorization (in the classification of Infeld and Hull). Transformations exist which allow the B, D, and F factorization types to be solved by the same method. General expressions are found for the eigenvalues corresponding to each of the relevant factorization types and a few specific examples are given. The eigenfunctions for the C-type and F-type problems are also discussed.
Coriolis Deflection of a Ballistic Projectile
Authors: Thompson Owen E.
Published: August 2005

The ballistic motion of a projectile in the gravitational field of the rotating Earth is considered. The deflection of the projectile from its azimuthol line of fire due to the rotation of the Earth is estimated by determining its three-dimensional trajectory from a set of three coupled equations of motion. The assumptions leading to this set of trajectory equations are itemized and interpreted. Conditions for the rightward and leftward deflection of the projectile are derived and compared to a recently published result. A straightforward physical interpretation of both leftward and rightward deflections is given.
An Experimental Simulation of Waves in Plasmas
Authors: Landt D. L. , Burde C. M. , Hsuan H. C. S. , Lonngren K. E.
Published: August 2005

The analogy between certain equations which describe wave propagation in plasmas and in a particular transmission line is observed. This observation has led to the construction of such a line and several current plasma problems are experimentally simulated on the line.
Proofs of Spontaneous Magnetization Using the Peierls Method
Authors: Bortz Alfred B.
Published: August 2005

One of the earliest proofs that a physical model exhibits a spontaneous magnetization was Peierls's [Cambridge Phil. Soc. 32, 477 (1986)] proof for the classical, two-dimensional, spin one-half Ising [Z. Physik 31, 253 (1925)] ferromagnet. The simplicity and beauty of this argument makes it an ideal topic for discussion in a statistical mechanics course. Recent work has extended the application of the Peierls technique to more sophisticated models. An extension to the classical two-dimensional, spin one Ising ferromagnet is discussed here. A review of the original Peierls argument as made rigorous by Griffiths [Phys. Rev. 136, A437 (1964)] is also presented. Other models to which the technique has been applied are also discussed briefly.
An Experimental Determination of the Velocity of Light from Stellar Spectrograms
Authors: Culver Roger B. , Leisure Robert G.
Published: August 2005

An elementary laboratory experiment is described for obtaining the value of the velocity of light from two or more stellar spectrograms using the Doppler effect and the concepts of relative motion.
Reality in Physics: A Classroom Discussion
Authors: Schlegel Richard
Published: August 2005

A classroom dialog form is used for a discussion of the question “What is reality?” It is agreed that a concept of reality which goes beyond immediate experience of phenomena is required. Empirical confirmation of expected properties is proposed as a reality criterion for physics. An allegation of falseness of physicists' reality concepts is made, with assertion of inadequacy for experiences of most people. A partial resolution is found in possible eventual description by a basic physical science. However, individuality among human beings suggests a role for humanists that is irreducible to that of scientists. Although the success of mathematics in physics supports a view that nature is essentially mathematical, the nature of mathematics and its comparative lack of success in some branches of science lead to a contrary position. A further argument is made from quantum physics that the inability of quantum theory to predict individual events argues against a completely mathematical character of physical reality. There is an analogy with individuality in human behavior, even though present-day science gives no information of connection. Mathematical properties are notable for a large domain of natural phenomena, but with apparent barriers to unlimited extension, in favor of fluctuation and diversity.
Teaching Objectives for a Liberal Arts Physics Laboratory
Authors: Flansburg Leonard
Published: August 2005

In the current era of decreasing support and increasing administrative accountability it is noted that measurable objectives are increasingly being required. The nature of accomplishable objectives is examined, and a list of behavioral teaching objectives for a liberal arts general physics laboratory is presented. The list includes minimum performance levels and illustrations as currently advocated by educators. The objectives are suggested on the basis of two arguments: first, that they provide a rationally sound basis for the selection of laboratory content, and second, that they are stated in the form that is currently being accepted by administrators and accountability experts.
A Humanistic Approach to Science
Authors: Roeder John L.
Published: August 2005

A new course, in which the relationship of scientist to humanity as well as to science is investigated, is described. A selection of student reactions to the initial offering of the course is presented, and the possible role of the course in science education is discussed.
Potential Energies of Identical Motion in Classical and Quantum Mechanics
Authors: Berkowitz David B. , Skiff Peter D.
Published: August 2005

Potential energies are found for which the stationary-state motion of a particle in a static force field is the same according to the Schrödinger equation as in classical mechanics.
A Laboratory Experiment Involving a Parallel LC Circuit Containing a Real Inductor (RL ≢ 0)
Authors: Harris Ronald W.
Published: August 2005

A discussion of a laboratory experiment involving a parallel LC circuit containing a real inductor (RL ≢ 0) is presented. By choosing component values to be confined to certain ranges, equations are presented for the (1) ratio of the output to input voltages, (2) Q of the circuit, and (3) phase of the output signal relative to the input. It is found that the phase goes to zero as the frequency decreases when a real inductor is used, rather than to π/2 as is the case for an ideal inductor (RL = 0). Experimental results are presented.
Computer Generated Films for Solid-State Physics
Authors: Hamilton John C. , Schwartz Judah L. , Bowers Wayne A.
Published: August 2005

A series of computer-generated films is described, intended to serve as pedagogic aids in presenting ideas concerning the motion of electrons in periodic potentials. Three films have been produced which illustrate the following phenomena: (A) propagation of wave packets of several different mean energies through the ideal crystal lattice; (B) reflection and transmission of a wave packet incident on a crystal from free space, for mean energy values lying (1) in an allowed energy band of the crystal and (2) in a forbidden gap of the crystal; and (C) scattering of a wave packet by an impurity atom in the lattice.
Thomas Precession and the Clock Paradox
Authors: MacKenzie K. R.
Published: August 2005

A simple derivation of the usual expression for the Thomas precession angle when v≪c is connected in a simple manner with the time difference in the clock paradox.
Thomson's e/m Experiment Revisited
Authors: Glascock Michael , Sparlin D. M.
Published: August 2005

The objective of this experiment is to familiarize the student with the impulse theorem, electron dynamics, and magnetic field contours. He is challenged to obtain accurate as well as precise measurements with suboptimum apparatus through correct analysis. He also investigates the influence of various systematic errors using model calculations on a small computer.
Motion of a Wave Packet Constructed from Landau Gauge Solutions
Authors: Thomson D. M.
Published: August 2005

The eigensolutions of the Schrödinger equation for the motion of a charged particle in a uniform magnetic field depend on the choice of electromagnetic gauge. In the Landau gauge it is hard to discern a relationship between the eigensolutions and the circular or helical orbits of classical theory. In this paper a wave packet is constructed from the Landau gauge eigensolutions which simulates the classical motion in the plane perpendicular to the magnetic field. Some properties of the wave packet are discussed.
Geometrical Relations for Charged Particles in a Uniform Magnetic Field
Authors: Thomson D. M.
Published: August 2005

By using appropriate gauge transformations one can develop quasiclassical wavefunctions for charged particles in a uniform magnetic field which have large amplitudes only in the neighborhood of classical Larmor orbits centered at arbitrary points in a plane perpendicular to the field. Pairs of such wavefunctions are not orthogonal to each other. Interesting geometrical relationships between these solutions and the degenerate orthonormal sets of wave-functions in a particular gauge can be found as a result of evaluating overlap integrals. This has been done for both the cylindrical and Landau gauges. In the cylindrical gauge certain of the orthonormal wavefunctions corresponding to different energies give identical probability distributions. Relationships between quantum and classical results, and the effect of the uncertainty principle are discussed.
Fabrication and Characteristics Study of a Surface Barrier Silicon Solid-State Particle Detector
Authors: Chuang L. S. , Tsui M. W.
Published: August 2005

The paper demonstrates how a surface barrier silicon solid-state particle detector can be fabricated and how its characteristics can be examined using simple methods and without the resources of an elaborate laboratory. The amount of money required to purchase one single detector from a manufacturer can be released to initiate a senior year student project in the course of which at least ten detectors can be produced.
The Use of Computer Generated Data in Experiment Design—A Student Exercise
Authors: Schectman Richard M.
Published: August 2005

An exercise in experiment design, envisioned for use in an undergraduate nuclear physics course, is herein described. The exercise utilizes several new methods of analysis, introduces the student to the use of the digital computer in simulating experimental data, and teaches the basic principles of experiment design.
The Thomas Precession
Authors: Fisher George P.
Published: August 2005

This paper is intended to give a simple physical understanding of the kinematic effect referred to as the Wigner rotation or, when applied to an orbiting object, the Thomas precession. Since this is a kinematic effect it applies not only to particles with spin but to all physical bodies in which a direction can be defined. To aid in avoiding the usual pitfalls in working with these problems, a review is made of several different approaches to the problem of an infinitesimally extended accelerating physical object. The central problem is in taking successive Lorentz transformations between parallel coordinate systems and clearly distinguishing between physical rotations of the object and coordinate rotations. When accounting for the energy associated with the Thomas precession a simple physical explanation is given rather than the misleading description popularly presented.
Action and Reaction in a Relativistic System: A Gedanken Experiment
Authors: Gruenstein Eric , Beron Bruce L.
Published: August 2005

A Gedanken experiment is presented in which a cyclotron with a man standing on top of it and two remotely located power packs are all initially at rest within a closed system. By a process of acceleration of cyclotron particles to relativistic velocities with consequent increase in cyclotron mass followed by a jump from the cyclotron and subsequent deactivation of the cyclotron, the momentum of the man-cyclotron system is increased. Momentum is shown to be conserved in the electromagnetic field generated during particle deceleration with cyclotron velocity remaining constant. However, a second activation-jump-deactiva-tion cycle gives rise to a considerably more complex problem of momentum conservation. In this case, the velocities of both cyclotron and power source must change in order to conserve momentum.
The Index of Refraction
Authors: Markley F. Landis
Published: August 2005

The phase velocity c/n of waves in a dielectric medium is known to arise from the interference of incident waves and waves emitted by the atoms in the medium, all traveling with speed c. As a model of a dielectric we consider a number of parallel sheets of charge with an electromagnetic wave normally incident on the sheets. The sheets are taken to be infinite in extent, which involves some rather delicate handling of infinities. The limiting case of an infinite number of sheets leads to an integral equation, the solution of which contains the usual formulas for light propagation in a dielectric.
Acoustic Radiation Pressure in a Traveling Plane Wave
Authors: Rooney James A. , Nyborg Wesley L.
Published: August 2005

A theory is developed for acoustic radiation pressure exerted by a plane wave on a perfect absorber, using Euler's momentum theorem. For the case of an open vessel, the radiation pressure P equals the mean energy density E even when nonlinearities of the medium and distortion of wave form are taken into account. For a closed vessel P equals [1 + 12(B/A)]E. The term B/A describes the non-linearity in the pressure-density relation for the medium and equals γ−1 for the case of an ideal gas under adiabatic conditions.
Mass Renormalization and Radiation Damping for a Charged Particle in Uniform Circular Motion
Authors: Boyer Timothy H.
Published: August 2005

The example of a charged point particle in uniform circular motion is treated from a pedagogical point of view within classical electrodynamics. The elementary analysis is of interest because it clearly separates out the finite radiation reaction force from the divergent mass renormalization term, and also because the particle is always treated as a point charge with the self-force found from evaluating the point charge fields over a surrounding spherical surface.
On the Goos-Hänchen Effect: A Simple Example of a Time Delay Scattering Process
Authors: Chiu K. W. , Quinn J. J.
Published: August 2005

A very simple analysis of the Goos-Hänchen effect, involving only elementary concepts of classical mechanics, is presented.
Polar and Axial Vectors in Electrodynamics
Authors: Brevik I.
Published: August 2005

It has recently been made clear that a simple change of purely formal conventions in electrodynamics has the immediate consequence that the magnetic field vectors H, B become polar vectors, similarly as the electric field vectors E, D. This paper discusses certain consistency problems that may arise in such a formulation of electrodynamics, wherein the usual distinction between “pseudo” and “true” quantities is lost. A consistency condition is given which is able to replace the condition from the usual formulation stating that any physical relation be covariant with respect to reflection of the coordinate axes. An example is considered.
Laplacian Operator in Spherical Coordinates, an Alternative Derivation
Authors: Chen F. M.
Published: August 2005

An alternative method for obtaining the Laplacian operator ∇2 in the spherical coordinate system from the Cartesian coordinates is described. The procedure consists of three steps: (1) The transformation from plane Cartesian coordinates to plane polar coordinates is accomplished by a simple exercise in the theory of complex variables. (2) The transition to cylindrical coordinates is made by utilizing the result of step (1). (3) The transformation from cylindrical to spherical coordinates follows by a second application of the result in step (1) and the evaluation of a first derivative. The great gain over the brute-force method is that the calculation of the second-order derivative is bypassed, thus avoiding most of the chain rule labor.
Polarization of Spin-1/2 Particles in Scattering Processes
Authors: Krase L. D. , Good R. H.
Published: August 2005

For a beam of spin-12 particles with definite momentum, a complete description of the spin state is provided by a single three-space vector, the polarization. This paper shows how the polarization-vector description provides a clear and vivid picture of spin effects in scattering processes. Explicit results are given for three types of interaction with a fixed source in first order: Coulomb, scalar, and pseudoscalar. The effect of a scattering is given by a vector-algebra formula, in which the final polarization is given in terms of the initial polarization and the momenta. In the Coulomb case, for example, the result of the scattering is that the polarization is rotated through an angle β about the normal to the scattering plane, in the same direction that the momentum is rotated. The rotation of the polarization is less than that of the momentum and the lag angle is given by cos(θ−β) = 1 − [(m/E) tan;12θ]21 + [(m/E) tan;12θ]2 where E is the electron energy and θ is the scattering angle.
Symmetries in Fraunhofer Diffraction
Authors: Hecht E.
Published: August 2005

Fraunhofer diffraction patterns display some rather interesting symmetries. The simple but common case where there is no phase variation in the incident electric field over the aperture is examined. In that situation the diffracted irradiance distribution possesses a center of symmetry regardless of the configuration of the aperture. Furthermore, the existence of symmetries in the aperture result in corresponding symmetries in the diffraction pattern. These properties are discussed in relation to eight illustrative photographs.
A Simple Problem in Mechanics: A Qualitative Approach
Authors: Flores J. , del Río A. G. , Calles A. , Riveros H.
Published: August 2005

The problem of a cylinder falling under the action of gravity in contact with a larger fixed cylinder is discussed from a qualitative point of view, both theoretically and experimentally. The same approach can be followed in a number of problems, and we think, can lead to a better understanding of classical mechanics, at least for the beginning student.
A New Derivation of the Lorentz Transformation
Authors: Landau B. V. , Sampanthar S.
Published: August 2005

It is shown that Newtonian mechanics plus the assumption that the mass of a particle varies with its velocity according to the formula m = m0(1 − v2/c2)1/2 leads to the Lorentz transformation.
Chemical Fluid Mechanics
Authors: MacRae Duncan
Published: August 2005

The theory of fluid mechanics can be profitably applied to chemistry by simply noting that many fluids are substances. Certain equations of fluid mechanics then become the counterparts of equations in the theory of the chemical thermodynamics of systems at constant temperature. Consequently, some of the most valuable parts of this theory may, for some purposes, also be regarded as a part of elementary physics completely independent of thermodynamics.
A Physics Survey Course with a Large Entropy
Authors: Ptak Roger L. , Stoner Ronald E.
Published: August 2005

Presenting physics to people who are not interested in science is a delicate and important task. In an effort to improve on the traditional style of survey courses, we have, over the last year and a half, conducted an experiment with a special section of our terminal physics survey, in which essentially everyone in our physics department participated. The experiment consisted of systematically removing as much structure as feasible within a lecture format. Evaluation indicates that student enthusiasm and performance increase as structure disappears.
Resistance in Absolute Units by a Combination of Bridge and Resonant Circuits
Authors: Ainslie Donald S.
Published: August 2005

The value, in absolute units, of a resistance was determined in a three-part experiment. In the first part a mica capacitor was measured in terms of resistance and the ac line frequency. In the second part an audio oscillator was calibrated in terms of the line frequency. In the third part a resonant circuit, incorporating the oscillator capacitor and a variable inductor, was tuned by varying the inductor which was then compared with a standard inductor. This gives the resistance in terms of the dimensions of the standard and ratios of resistances and frequencies.
Maximum Range of a Projectile in Vacuum on a Spherical Earth
Authors: Blitzer Leon , Wheelon Albert D.
Published: August 2005

Expressions are derived for the maximum range of a projectile in vacuum on a spherical earth in terms of the ratio of kinetic to potential energy at launch. These results are combined with those for the corresponding launch angle and presented graphically. Limiting conditions are discussed, and the effect of the earth's rotation is indicated.
Hamilton's Principle as a Computational Device
Authors: Miller P. H.
Published: August 2005

Hamilton's principle is used as a computational device to obtain the period of a simple pendulum and a bead sliding along a parabolic wire to second-order terms in the amplitude. We assume a motion of the form θ = θ0 sinωt and ask the following question: How shall we choose the amplitude θ0 so as to make the line integral of the Lagrangian extremum for the observed period τ = 2π/ω? In the case of planetary motion and for the simple functions selected the period is given correctly only to first-order terms in the eccentricity.
Study of Classical Scattering Theory
Authors: Gordon M. M.
Published: August 2005

The classical theory of the scattering by a conservative central force is re-examined. A variational equation and a Fourier series expansion are developed whereby approximate expressions for the trajectory can be obtained. In addition, impulse integral equations are derived from which approximate relations between energy, impact parameter, and scattering angle can be developed. These methods are applied to potentials of the form V = C/rn and the results are found to be quite superior to those from the widely used small-angle approximation.
Introductory Physics Laboratory
Authors: Nedelsky Leo
Published: August 2005

It is argued that the central function of the introductory physics laboratory is to acquaint the student with various aspects of the relation of physics to reality. Appropriate conditions of learning are described and illustrated. It is further argued that the proposed experiment-predict-verify pattern of laboratory exercises would stimulate students' interest and could be easily incorporated into the existing structure and facilities of the average physics course.
Negative Resistance
Authors: Mackay R. Stuart
Published: August 2005

Relaxation oscillations and other discontinuous phenomena in nature are considered in terms of the regenerative feedback needed for their appearance. In the electrical case the concept of negative resistance is often especially convenient and the present paper attempts to summarize and discuss this, as well as to present a novel current vs voltage characteristic of more complicated form. Some counting devices, impulse propagators, and several nonstationary systems are mentioned and there are explanations in terms of analogous nonelectrical systems.
Note on a Problem Concerning the Gibbs Paradox
Authors: Klein Martin J.
Published: August 2005

This note deals with the Gibbs paradox for the following case. An ideal gas A is allowed to mix with an ideal gas A* whose atoms are all A atoms in an excited metastable state. It is shown that after a time long compared to the lifetime of the metastable state there has been an entropy increase larger than the mixing entropy which “disappears.”
Measurement of the Capillary Curve
Authors: Dempsey Daniel F.
Published: August 2005

The surface of a liquid in contact with a plane wall has a shape which can be obtained by integrating the differential equation of capillarity. Measurements taken give good agreement with the theory.
Liquid Rope-Coil Effect
Authors: Barnes George , Woodcock Richard
Published: August 2005

The tendency for a falling stream of very viscous liquid to coil like a rope when it strikes a horizontal surface is studied and the building of a “cone” of liquid of considerable height above the surface is observed. It is shown that, although the liquid stream as a whole appears to rotate about the axis of the “cone,” the particles of liquid do not actually rotate about this axis. Variations of the liquid rope-coil effect are discussed.
Recent Advances in Physics
Authors: Park David
Published: August 2005

During the last two decades it has become virtually impossible even for a conscientious research physicist or physics teacher to study enough original papers in the literature to keep him abreast of the progress of physics. Recognizing the need for readable accounts of recent developments, the American Institute of Physics published annual summary articles in the Review of Scientific Instruments and the Journal of Applied Physics covering the period from the mid-thirties to the mid-forties, the last one being written by Philip Morrison. Since then, the need for a continuation of this type of writing and publication has become increasingly apparent to the American Association of Physics Teachers, whose Executive Committee, in January, 1957, authorized the Editor of the American Journal of Physics to commission an article on recent advances in physics designed for the general reader. Here it is, by David Park, Associate Professor, Williams College. He has intentionally designed different portions of his article to appeal to readers within a wide range of background knowledge.

The Journal hopes to be able to continue this service to its readers. Since the Editor's and author's judgments of what is needed are fallible, they welcome criticism, comment, and suggestions with respect to length, coverage, selection of material and, especially, level of treatment. A review such as Professor Park has written is of necessity a long time in preparation; hence, readers should send their opinions to the Editor without delay.
Pressure-Volume Relations in Solids
Authors: Duvall George E.
Published: August 2005

An equation of state of the form P(V) = f(V) + Tg(V), which is useful for condensed matter, is proposed for the illustration of thermodynamic principles. Pressure-volume relations for adiabatic and shock compressions are derived with the assumption that specific heat at constant volume is independent of temperature. These derived relations are illustrated for a “Murnaghan” equation of state, and constants of this equation for several metals are tabulated.
Experiments with Condensers
Authors: Leifson S. W.
Published: August 2005

A zero-current triode voltmeter developed by the author is used to measure the voltages of condensers in various series and parallel combinations. Good agreement is obtained between the observed results and those predicted from theory. Attention is called to the experimental demonstration of the conservation of charge.
Concept of Energy as the Theme of a General Education Course in Physics
Authors: Lindsay R. B.
Published: August 2005

The paper describes an experimental course in general education physics based on the concept of energy as the central theme. The course has been given to undergraduate liberal arts students with little or no previous education in science. Handled entirely by the class discussion method, the course has sought to stress energy as not only the premier concept of physical science but also the key to other vast areas of human experience.
The Spirit Giveth Life
Authors: Bartunek Paul F.
Published: August 2005

The thesis that physics should be approached as a creative research activity at all levels, including the elementary level, is presented. A typical sophomore mechanics experiment which fosters the creative attitude is described. Some suggestions for approaching the creative ideal in laboratory learning are set forth.
Physics and the Medical Student
Authors: Stewart Peter A.
Published: August 2005

To understand the complex phenomena of physiology and medicine, medical students need broader and deeper physics training than the usual general physics course. This requires an improvement in their motivation towards physics, as well as a presentation of physics courses more appropriate to their psychological block against anything mathematical.
Physics and Medical Research
Authors: Bruner H. D.
Published: August 2005

The place of physics as a premedical study has not been sufficiently emphasized in recent years to satisfy the need for this discipline by the student in medical school, particularly the first two years of medical school. An analysis of the use of the techniques of physics in eight recent medical research journals indicates that the premedical student must receive added instruction in physics to qualify him for the present developments in medicine.
Note on the Measurement of e/m by the Hoag Method
Authors: Soemitro  , Prawirowardojo Susilo , Dickinson W. C.
Published: August 2005

The value of e/m obtained by the Hoag method depends critically on the choice of measuring origin for l, the distance from the oscilloscope deflecting plates to the screen. We have determined the correct origin by solving the equations of motion for the electron trajectories. It is concluded that only a single set of unflared deflecting plates should be present in the oscilloscope tube if one or two percent accuracy is desired.
Opportunities and Responsibilities in Science Education
Authors: Reynolds Thomas D.
Published: August 2005

Science and mathematics departments of colleges and universities are becoming increasingly active in developing programs designed to improve instruction of science and mathematics. Many factors contribute to this increased interest. Financial support by the National Science Foundation provides opportunities for colleges and universities to develop science and mathematics programs that will be most suitable for teachers. Financial assistance is also provided for teachers attending these programs.