bluuebunny/crossref_metadata_2025 huggingface dataset:
Variational Principle for Certain Nonconservative Systems
Authors: van der Vaart H. Robert
Published: August 2005

It is shown that the equation of motion of a linear dissipative system with one degree of freedom can always be derived from a suitably chosen variational principle. In the case of more than one degree of freedom, this is shown to be true only if the system satisfies a certain condition, which is explicitly given.
Free Rotation of a Rigid Body Studied in the Phase Plane
Authors: Deprit André
Published: August 2005

A homogeneous canonical transformation reduces the free rotation of a solid body to a conservative Hamiltonian system with only one degree of freedom. This reduction permits the representation of all possible solutions of the Euler-Poinsot problem by isoenergetic curves in a phase rectangle. Such a diagram illustrates the stable or unstable character of a permanent rotation around an axis of inertia.
The Way of the Chemical Potential
Authors: Kittel C.
Published: August 2005

A large class of problems in statistical physics is very simple when treated by means of the chemical potential. In this paper the chemical potential is applied to eight problems of physical interest, with particular emphasis on solid-state physics. The method could profitably be emphasized in junior or senior courses in statistical physics.
Experimental Studies of Magnetic Properties of a Metal in the Normal and Superconducting States
Authors: Balcombe R. J. , Perz J. M.
Published: August 2005

Experiments have been designed for the measurement of the magnetoresistance of a normal metal and of the critical field dependence of a superconductor. The equipment is relatively cheap and simple to construct and operate, and the experiments yield accurate results in times short enough for inclusion in an undergraduate laboratory class.
Wave Propagation in Inhomogeneous Gyrotropic Warm Plasmas
Authors: Unz H.
Published: August 2005

The three-dimensional wave equation for waves propagating in inhomogeneous warm compressible plasma with an imposed arbitrary inhomogeneous static magnetic field is derived from the macroscopic linearized equations, of the single-fluid continuum-theory plasma dynamics. Particular cases are discussed and compared with previous results.
Some Observations on NSF-Supported Secondary Institutes in Physics
Authors: Maxwell Howard N.
Published: August 2005

In the NSF Secondary Summer Institute Program, the number of physics institutes supported and the percentage of physics proposals funded is less than for other disciplines. Reasons for this situation and some suggestions for remedying it are set forth.
Minimum Size of Proton and Electron in a Nonrelativistic Theory from Hyperfine Structure
Authors: Lewis Michael L.
Published: August 2005

In a nonrelativistic theory, the “contact” interaction between two point particles has a delta-function singularity. It is shown for the attractive case that this leads to an infinite binding energy for the ground state, and hence cannot be physically meaningful. The hyperfine shift in the energy is calculated, using the variational principle, for a smeared-out interaction both for hydrogen and positronium. It is found that the binding energies become unphysically large if the sizes of the particles are reduced beyond a certain nonzero limit which represents the minimum size of the particle.
Measurement of Atomic Lifetimes by the Hanle Effect
Authors: deZafra R. L. , Kirk W.
Published: August 2005

An experiment is described which utilizes the Hanle technique for measurement of atomic excited-state lifetimes, with particular application to the P13 state of mercury. The components for the experiment are comparatively inexpensive or readily constructed, and the technique is one of the few which directly illustrate features of the interaction between radiation and free atoms. A simple classical description of the effect is given, followed by a more detailed quantum description, as well as constructional details of an experimental arrangement suitable for an advanced undergraduate or graduate laboratory.
Nuclear Physics Experiment for the Senior Physics Laboratory
Authors: Jordan J. A. , Duval J. S.
Published: August 2005

An experiment for the Rice University Senior Physics Laboratory has been developed around the F(p, α)19 O16 reaction. The experiment serves to introduce the student to nuclear spectroscopy in an environment almost identical with the research environment. The experiment makes use of a 5.5-MeV Van de Graaff accelerator and an on-line computer analyzer. The students are given much freedom to choose the measurements to be made, and are expected to devise methods for processing the data accumulated.
Sign Conventions in Geometrical Optics
Authors: Sukheeja B. D.
Published: August 2005

A set of sign conventions to be used in the derivation and application of mirror and lens formulas in geometrical optics is proposed. Some examples are presented to show that the formulas derived with the proposed conventions have greater uniformity and that these conventions correspond to the physical process (convergence or divergence) taking place at a spherical reflecting or refracting surface.
On Degenerate Time-Independent Perturbation Theory
Authors: Soliverez Carlos E.
Published: August 2005

A formalism is presented in which both the degenerate and nondegenerate cases can be treated in the same fashion. Nonlinear integral equations are written for the perturbed wavefunctions, which lead to the usual formulas when solved by iteration. The method provides a simple way to set—up to any desired order—secular equations for the energy shifts and zeroth-order perturbed wavefunctions.
Longitudinal Spherical Aberration of a Thin Lens
Authors: Friedmann G. B. , Sandhu H. S.
Published: August 2005

An improved and simple undergraduate technique for determining the longitudinal spherical abberation (LSA) of a thin lens is described. It is shown that the results agree within 5% with the values calculated using the usual approximation made in the third-order aberration theory.
Collective Model of the Giant Resonances
Authors: Huber Max G.
Published: August 2005

The collective model of the giant resonances is described. The dipole vibrations are discussed in greater detail and applied to both spherical and deformed nuclei. In a consistent expansion of the model the collective-charge vibrations are coupled to the low-energy nuclear-surface vibrations. The implications of this dynamical treatment on the photoabsorption cross section are discussed and compared with the experiments. The properties of other kinds of collective motions such as spin waves and spin-isospin waves are reviewed. Finally the connection between the collective picture of charge vibrations and the shell-model treatment of the giant resonances is pointed out.
Polarized Spin-One Particles
Authors: Darden S. E.
Published: August 2005

A simplified treatment of polarization effects in scattering of spin-one particles is presented. The analogy between spin moments and electric multipole moments is exploited. Elementary physical arguments illustrating the mechanism of polarization are given for two specific interactions.
American Institute of Physics Programs in Education—Present and Future
Authors: Strassenburg Arnold A.
Published: August 2005

The well-publicized decline in high school physics enrollments is reviewed. Considerable evidence is presented to document the shortage of qualified high school physics teachers. When such statistical studies reveal educational problems, effective improvement programs can be established. Specific programs designed to increase high school physics enrollments and to improve teacher preparation programs are discussed. Recently released statistics have confirmed the decrease in the number of physics baccalaureate degrees granted in 1965; extrapolations of present trends predict a serious decline in college physics majors in the immediate future. Methods of combatting these trends are considered. The American Institute of Physics announces a new College Physics Program designed to assist colleges to conceive and implement plans for curriculum improvements. Data on the education and employment of physicists are summarized. No claims of drastic future shortages are made, though the author sees a great need for more detailed surveys designed to assess future demand for physicists trained at various levels. The value of such studies in helping to identify needed new educational programs is stressed.
Aberration of Light from Binary Stars—a Paradox?
Authors: Eisner Edward
Published: August 2005

It is widely believed that aberration, like the Doppler effect, depends on the relative velocity of source and observer. It is here shown that, if this were true, binary stars would mostly look widely separated and rapidly rotating. Not only is this not observed, but it would appear to conflict with Kepler's third law if it were. It is argued that aberration does not depend on the relative velocities of source and observer: it depends only on the change in velocity of the observer between the times when the two measurements from which the aberration is deduced are made. The misconception is due to a faulty customary interpretation of the correct standard treatment.
Axial Mode Number of Gas Lasers from Moving-Mirror Experiments
Authors: Peek Th. H. , Bolwijn P. T. , Alkemade C. Th. J.
Published: August 2005

The laser-power-output modulation, obtained by reflection of the laser beam back into the resonator by means of an external moving mirror (EMM), is analyzed in terms of resonator Q modulation. The variation of the amplitude of the output-power modulation as a function of the distance EMM laser is characteristic for the number of excited axial modes. Experiments were performed with various commercially available He-Ne lasers, showing clearly one, two, three, and more modes. A comparison is made with similar experiments which may be made in a Michelson moving-mirror interferometer. An additional feature of EMM modulation is that the saturation of the laser transition in a single-mode laser can easily be demonstrated. The experimental procedure and arrangement are simple, and it is believed that the work presented may have value for demonstration and education.
Causality in the Coulomb Gauge
Authors: Brill O. L. , Goodman B.
Published: August 2005

A theoretical description and comparison of causal relations in the Lorentz and Coulomb gauges is presented with special emphasis upon retardation in the Coulomb gauge. It is shown that the transverse character of the current density in the Coulomb gauge compensates for the apparent instantaneous Coulomb interaction, which appears as a formal consequence of the subsidiary condition imposed upon the vector and scalar potentials.
Germanium Detectors and the Compton Effect
Authors: McDaniels David K. , Battleson Kirk
Published: August 2005

Recent advances in solid-state lithium-drifted germanium detectors have opened a new era in gamma-ray spectroscopy. A typical detector system is described which could easily be incorporated into an advanced teaching laboratory. The measurement and analysis of gamma-ray spectra from radioactive isotopes is reviewed. As an example of a further experiment, the Compton recoil distribution in a germanium crystal is compared with the Klein-Nishina prediction. Difficulties in making a quantitative comparison are discussed.
Quantum-Mechanical Treatment of the Hydrogen Atom without Complicated Mathematics
Authors: Cohen B. L.
Published: August 2005

It is pointed out that treatments of the quantum mechanical hydrogen atom in elementary modern physics texts are generally either hazy or physically incorrect. A treatment using only elementary mathematics is given which yields the correct functional dependence, and reasonably accurate values for the Rydberg constant and the Bohr radius, qualitatively correct wavefunctions, and a semiquantitatively correct energy-level diagram. Above all, it gives and utilizes the correct physical reason for all of these features.
Introduction to Many-Body Formalism
Authors: Neidhardt W. Jim
Published: August 2005

An elementary approach is presented to the many-body formalism needed to understand simple models of superfluid systems. In the framework of occupation number space-particle conserving operators that represent single-body and two-body observables are constructed in an intuitive manner. It is then shown that this formalism when applied to such observables as single-particle energy and two-body interaction potential yields results which are physically plausible. The basic formalism for the understanding of many-body systems is thereby presented without recourse to a complete development of quantum field theory.
Matrix Description of Collisions on an Air Track
Authors: Romer R. H.
Published: August 2005

A variety of situations is described in which two gliders ride on an “air track” and undergo collisions with each other and with reflecting springs at the ends of the track. In many cases the observed sequence of events has a regular and repetitive behavior, in which the initial conditions are restored after a long sequence of collisions. A general matrix formalism is established for the description of such sequences of collisions, and it is shown that in many cases, the regularities can be easily understood in terms of the properties of the collision matrices, independent of the mass ratio of the gliders. A class of sequences in which the mass ratio is of critical importance is suggested by the formalism and experimentally confirmed. An equivalent geometrical description is given in which a sequence of collisions can be described as simply a succession of rotations and reflections, without change of length, of a “velocity vector” in “velocity space.”
Nature of Radio Waves Reflected from an Undulating Surface
Authors: Austin G. L.
Published: August 2005

The character of signals reflected from a sinusoidal-shaped surface is discussed with particular reference to the ionosphere and an experimental verification of the essential features obtained using a model and microwaves is presented.
Quantum Noise in Optical Parametric Devices
Authors: Louisell William H.
Published: August 2005

The technique of field quantization is applied to the radiation field as well as elastic vibrations in order to obtain a model for a phonon laser. The quantum noise limitations are discussed as well as the effects of phase matching.
Octonions and the Dirac Equation
Authors: Penney R.
Published: August 2005

Octonions, or Cayley numbers, are used to extract the square root of the classical relativistic Hamiltonian, in place of the usual Dirac matrices. The resulting wave equation, analogous to the usual Dirac equation, is found to be equivalent to a pair of coupled Dirac equations. Thus, the introduction of the octonion algebra in place of the Dirac algebra provides nothing new in principle within the context of linear relativistic wave equations.
A Laboratory Approach to an Eigenvalue Problem
Authors: Clendenning Lester M.
Published: August 2005

An experiment is described that requires a minimum amount of equipment usually found in the undergraduate physics laboratory. The experiment is designed to serve as an introduction to eigenfrequencies. It consists of two equal lengths of different-density thin wires joined and held horizontally under a known tension. One section of the wire sits in a magnetic field of a simple horseshoe-type magnet. If a current from an audio generator is passed through the wire, the interaction between the two magnetic fields causes the wire to undergo oscillations. Resonance occurs when the frequency of the oscillator is a normal mode frequency of the two-wire system.
Teaching of Physics of Fluids in U.S. Colleges and Universities
Authors: Emrich Raymond J. , Snyder Howard A. , Uhlenbeck George E.
Published: August 2005

The values are presented for including the concepts and laws of fluid dynamics within physics programs. The extent of teaching and the extent of knowledge expected of a graduate have been found by a survey of U.S. schools. Proposals are made for helping physics teachers include more about fluids in their courses and curricula and a list of topics constituting fluid dynamics as a part of physics is included.
An Experiment-Oriented General Physics Course
Authors: Snyder Donald D.
Published: August 2005

An experiment-oriented course of introductory general physics was carried out by the author and eight volunteer students at Andrews University, Berrien Springs, Michigan, during the 1963–1964 school year. This paper reports on the structure of the course and the evaluation of the approach from the vantage point of 312 years' elapsed time. The course used experiments to introduce and develop most of the topics normally covered in a course of introductory college physics. Teacher and students are generally enthusiastic about the approach and think it should be further developed.
Classical Transformation Operators and the S Matrix
Authors: Campbell Philip M.
Published: August 2005

A novel formulation of classical dynamics in terms of differential operators is presented. The basis for this formulation is the direct application of the unfolding theorem for arbitrary times. The solution of a mechanical problem is given by the operator method as a Taylor series about the initial point. The classical operator formalism has similarities with quantum mechanics. It is shown that classical scattering can be described in terms of a classical S-matrix operator. Examples are given.
Green Function Theory of the Two-Spin System
Authors: Lucas Gary L.
Published: August 2005

The exact solution of the two-spin Heisenberg model with an external field is obtained by means of a Green function technique. The results are compared with an approximate solution of Patterson and Southwell in which a Tyablikov decoupling approximation is used. The special problem associated with the calculation of the zero-frequency component of the correlation function is also discussed.
Approximate Expressions for the Potential Distribution in Junction Semiconductor Devices
Authors: Tobin Marvin C.
Published: August 2005

Approximate solutions, valid near the junction or distant from the junction, are derived for several simple junction semiconductor devices. These solutions are useful for quick calculations of trends. Several simple numerical examples are given.
Dynamics of a Simple Maser Model
Authors: Shirley Jon H.
Published: August 2005

A simple maser model consisting of a single-mode field coupled to N identical two-level atoms is presented. The assumption of negligible statistical correlation between the atoms and the field, permits the Heisenberg equations of motion to be replaced by a self-consistent set of ordinary nonlinear differential equations. Relaxation terms and an energy source are introduced phenomenologically. The resulting equations exhibit a threshold, stable and unstable steady states, relaxation oscillations and, sometimes, spiking. The dynamic equations for the hydrogen maser and the rate equations of laser theory are derived as special cases. Also discussed are the maser amplifier, locking of a maser to an external signal, and the effects of cavity thermal noise.
A New Design for Lecture Auditoria
Authors: Walz Frank C. , Bartlett A. A.
Published: August 2005

Many contemporary lecture halls have been designed in conventional ways that tend to maximize the seating capacity but that overlook serious operational problems. A design is presented which, it is hoped, will overcome many of these problems.
Radiometry and Photometry
Authors: McCluney W. R.
Published: August 2005

In order to reduce the confusion associated with many of the introductory treatments of photometry, it is suggested that initially the concepts of radiation transfer be introduced in terms of the more familiar units of radiometry. The conversion to photometric units can then be accomplished by a straightforward integration. The approach is illustrated with five of the basic quantities of radiometry.
An Eigenfunction Solution of a Problem in Heat Conduction
Authors: Giere A. C.
Published: August 2005

The time-dependent one-dimensional equation of heat conduction is solved for a slab of two layers possessing different thermal characteristics and with the following boundary conditions. One face is kept at a constant temperature, and at the other face there is a heat flux which depends linearly on the temperature there. The initial temperature distribution is left arbitrary. The solution is obtained by the classical method of separation of variables and several significant concepts inherent in this method are put in evidence. In particular, the nature and properties of the eigenvalues and eigenfunctions are investigated in some detail.
Artistic Invitations to the Study of Physics
Authors: Holden Alan
Published: August 2005

The Robert A. Millikan Lecture Award is made annually to a physicist chosen by a special committee of the American Association of Physics Teachers because of his creative and imaginative contributions to the teaching of physics. The lecturer selected is one whom the Association wishes to honor at the Summer Meeting in the same way that it honors the Oersted Medalist at the time of the Annual Meeting. The award is made possible through the annual support of Prentice-Hall, Inc.; the first award was made in 1964.

The recipient of this award for 1968 is Alan Holden, Member of the Technical Staff, Bell Telephone Laboratories.
The Individual Particle Description of Nuclear Giant Resonant States
Authors: Tomusiak E. L.
Published: August 2005

The isospin, spin, and spin-isospin modes of collective nuclear excitation are reviewed in a form suitable for presentation in a graduate-level nuclear physics course. The transition charge and current densities as given by a shell model description of these collective states are compared to those of the hydrodynamical theory. These densities are demonstrated to be identical in form if the individual particle model is based on an oscillator potential and if the usual custom of keeping only the first derivative in a Taylor expansion of the hydrodynamical charge operator is adopted. Only doubly closed-shell nuclei with N = Z are considered.
Behavior of the Complex Refractive Index of an Isotropic Plasma
Authors: Habert R. , Samaddar S. N.
Published: August 2005

This note presents the study of the behavior of the real and imaginary parts of the complex refractive index of a homogeneous isotropic plasma. The independent variable is either x =thinsp;ν/ω or y = (ωp/ω)2 while the other quantity y (or x) is considered to be a parameter and held constant. It is shown that both the real and the imaginary parts of the refractive index may possess extrema. They are maxima when x alone is varied while they may be minima when y alone is varied. The present investigation supplements the work of Ratcliffe.
Motion of an Elastic Ball on a Regularly Corrugated Surface
Authors: Emtage P. R.
Published: August 2005

The motion of a perfectly elastic ball on a regularly corrugated level surface resembles that of an electron in a periodic lattice in that uniform progression across the surface is possible only when the energy of the ball lies within one of a number of discrete regions. These regions correspond to rolling and to even bouncing from ridge to ridge; other simple bouncing motions are found to be unstable, and it is shown that the bands of energy corresponding to more complex stable modes of propagation, if they exist, must be very narrow.
Dimensionally Correct Transformations between Different Systems of Units
Authors: Weibel E. S.
Published: August 2005

A method which allows the dimensionally correct transformation of equations from one unit system to another is described. Three sets of transformations are explicitely given for the passage between (1) the Gaussian and the mks system, (2) the mks and a natural rationalized system with c = 1, and (3) the mks and a natural rationalized system with c = 1, ħ = 1.
Canonical Transformation Governing Temporal Development in Classical Mechanics
Authors: Tani S.
Published: August 2005

A simple recursion formula is introduced for the derivation of the generating function of the canonical transformation in classical mechanics in the form of a power series in t, where the transformation relates a variable at the time t with its initial value given at t = 0. A discussion is given of the relationship of this approach to the Hamilton-Jacobi differential equation, with emphasis on the comparison of the formal aspects of classical and quantum mechanics.
Anniversaries in 1968 of Interest to Physicists
Authors: Barr E. Scott
Published: August 2005

During the year 1968 there are major anniversaries of the birth or death of eleven men whose accomplishments and influence have been of importance to the development of physics. They are: David Brewster, Jean Bernard Léon Foucault, Jean Baptiste Joseph Fourier, James Prescott Joule, John LeConte, Robert Andrews Millikan, Gaspard Monge, Wallace Clement Ware Sabine, Arnold Johannes Wilhelm Sommerfeld, John Sealy Edward Townsend, and Robert Williams Wood. Brief accounts of their lives and achievements are given here.
How Good is the Hartree-Fock Approximation
Authors: Moshinsky M.
Published: August 2005

The problem of two particles in a common harmonic oscillator potential interacting through harmonic oscillator forces is discussed from the standpoint of the Hartree-Fock approximation and compared with the exact solution.
Rays from a Parabolic Reflector for an Off Focal-Point Source
Authors: Lazar Irving , DeAcetis Louis A.
Published: August 2005

The exact solution for rays emanating from a two-dimensional parabolic reflector is obtained using Fermat's principle. The results are presented graphically (using the IBM 1627 plotter) for various positions of the source, both close to and far from the focal point of the mirror.
Maxwell's Electrostatics
Authors: Bromberg Joan
Published: August 2005

Maxwell first introduced displacement as a synonym for Faraday's dielectric polarization. However, the equations expressing his electrostatics were altered by Maxwell in the successive versions of his theory, and those which ultimately governed displacement did not allow it its original meaning. Displacement, therefore, came to be viewed as a totally new quantity, originating with Maxwell.
Speed of Light
Authors: Ockert Carl E.
Published: August 2005

Extinction considerations are used to evaluate the instantaneous velocity of light as it traverses a moving medium in a series of discrete steps, each step defined by extinction and re-emission of the photon. The analytical results agree with the experimental values obtained by Fizeau if the instantaneous velocity between extinctions is C relative to the laboratory, and C ∓ v relative to the fluid moving at velocity ± v. It is shown that this implies a verification of the convective ether hypothesis of D. C. Miller. Further testing of this hypothesis is suggested, using modified arrangements for the Fizeau experiment.
Resource Letter GR-1 on General Relativity
Authors: Brill Dieter R. , Perisho Robert C.
Published: August 2005

Prepared at the request of the AAPT Committee on Resource Letters; supported by a grant from the National Science Foundation.

This is one of a series of Resource Letters on different topics, intended to guide college physicists to some of the literature and other teaching aids that may help them improve course contents in specified fields of physics. No Resource Letter is meant to be exhaustive and complete; in time there may be more than one letter on some of the main subjects of interest. Comments and suggestions concerning the content and arrangement of letters as well as suggestions for future topics will be welcomed. Please send such communications to Professor Joel Gordon, Chairman, Resource Letter Committee, Department of Physics, Amherst College, Amherst, Massachusetts.

Notation: The letter E after the item number means that the reference should be mainly useful for elementary courses. In view of the complexity of the subject elementary will normally imply junior courses. The letter I indicates intermediate (senior and first-year graduates) and A indicates advanced (second-year graduates and students beginning research in Physics). An asterisk (*) indicates items particularly recommended for introductory study.

Additional copies: Available from American Institute of Physics, 335 East 45 Street, New York, New York 10017. When ordering, request Resource Letter GR-1 and enclose a stamped return envelope.
Dilute Solutions of He3 in He4 at Low Temperatures
Authors: Wheatley John C.
Published: August 2005

Properties of dilute solutions of He3 in He4 at low temperatures and their application to dilution refrigeration are discussed from a review—tutorial point of view. A comprehensive review of the properties of dilute solutions is not given. Rather, the simple physical notions underlying an understanding of their properties are discussed. Special emphasis is placed on those phenomena which are of importance in understanding the dilution refrigerator. After a review of the phase-separation phenomenon in He3-He4 solutions, the experimental and theoretical basis for the effective interaction between He3 quasiparticles is discussed. Then the energy of the He3 quasiparticles, their chemical potential, and their dependence on the local density and velocity of the superfluid are treated. A few brief remarks on a possible superfluid transition are made. A discussion is given of the qualitative aspects of different types of dilution refrigerators: the “evaporation”-like continuous and single-cycle refrigerators and the “adiabatic expansion”-like superleak operated dilution refrigerator. Then a thermodynamic treatment of these refrigerators is given. Finally some numerical and graphical information, based on the actual properties of He3 and dilute solutions, is given to illustrate the possibilities and problems of the methods.
Canonical Transformations without Hamilton's Principle
Authors: Ludford G. S. S. , Yannitell D. W.
Published: August 2005

A simple and direct derivation of the properties of canonical transformations is given, starting from their fundamental property of leaving Hamilton's equations unaltered. No appeal is made to the calculus of variations, and none but the most elementary calculus is used.
Simple Derivations of the Schwarzschild Metric
Authors: Sacks William M. , Ball John A.
Published: August 2005

Two derivations, one of the Schwarzschild line element, the other of the gravitational bending of light, both using only special relativity, the equivalence principle, and the Newtonian law of gravity, are examined in detail and shown to be incorrect. In both derivations equations of the correct form were derived, but the physical meanings of the symbols are not what they purport to be. The postulates, in addition to the above three that are necessary to derive the bending of light, are discussed briefly.
Shell Model of Nuclear Structure
Authors: Meyer Eugene
Published: August 2005

The shell model of the nucleus is reviewed as a pure “single-particle” model emphasizing recent spectroscopic evidence. Qualitative evidence for “magic numbers” is reconsidered in the light of current data. A partial listing is given for nuclei where spectroscopic evidence points towards shell model structures.
A Laboratory Course for Nonscience Majors
Authors: Fryshman Bernard
Published: August 2005

A laboratory course designed to meet the special needs of the nonscience major is described. Based on the approach of the scientist to a research problem, this sequence offers some very definite advantages to the instructor as well as to the student.
Derivation of the Nonadditive Triple-Dipole Dispersion Energy Using Elementary Electrostatics
Authors: Graben H. W.
Published: August 2005

The classical explanation of the two-body dispersion energy is extended to the three-body problem. The well-established formula for the three-body dipole-dipole interaction energy is deduced from elementary electrostatic considerations without the use of wave mechanics.
Graphical Method of Illustrating Relativistic Conservation Laws
Authors: Hegarty John C.
Published: August 2005

Graphical methods can be utilized to analyze relativistic free-particle interactions by representing the momentum of a free particle as a vector in two-dimensional momentum space. This vector is constrained to lie on the mass hyperbola for all inertial frames of reference. By employing the Lorentz invariance of the difference in the hyperbolic angles for any two vectors, one can analyze graphically free-particle interactions in the most convenient frame of reference. In particular two-particle interactions are studied in the laboratory and center of mass frames of reference.
Resource Letter OE-1 on Origin of the Elements
Authors: Fowler William A. , Stephens William E.
Published: August 2005

Prepared at the request of the AAPT Committee on Resource Letters; supported by a grant from the National Science Foundation.

This is one of a series of Resource Letters on different topics, intended to guide college physicists to some of the literature and other teaching aids that may help them to improve course contents in specified fields of physics. No Resource Letter is meant to be exhaustive and complete; in time there may be more than one letter on some of the main subjects of interest. Comments and suggestions concerning the content and arrangement of letters as well as suggestions for future topics will be welcomed. Please send such communications to Professor Joel E. Gordon, Resource Letter Committee, Department of Physics, Amherst College, Amherst, Massachusetts 01002.

Notation: The letter E after an item number indicates elementary level, useful principally for high school and introductory college use; the letter I indicates intermediate (junior, senior) level; and the letter A indicates advanced material, principally suited for senior, graduate study. An asterisk (*) indicates items particularly recommended for introductory study.

Additional copies: Available from American Institute of Physics, 335 East 45 Street, New York, New York 10017. When ordering, request Resource Letter OE-1 and enclose a stamped return envelope.
Films (16 mm) for Students of Physics
Authors: Weber Robert L.
Published: August 2005

Some 1020 films useful for instruction in physics, mostly at the college level, are listed by field. Addresses of distributors are given. This listing, which includes some foreign films, is intended to be helpful to instructors seeking suitable films for classroom use in school and college, and to those planning future films. Some comments are made on the availability and suitability of 8 mm films.
Integral-Differential Equation for the Temperature-Dependent Spatial Distribution Function
Authors: Kostin M. D.
Published: August 2005

An integral-differential equation was derived for the temperature-dependent spatial distribution function of quantum statistical thermodynamics and analytical solutions for several quantum systems were given. It was shown that the classical and quantum-mechanical equations for the temperature-dependent spatial distribution function for a separable potential differ by one term proportional to Planck's constant squared. In several limiting cases it was found that solutions obtained from the integral-differential equation agreed with those obtained by Uhlenbeck using other methods.
Boundary Conditions for Spherical Sound-Wave Propagation
Authors: Johnson James N.
Published: August 2005

This paper presents a coherent approach to the theory of spherical sound-wave propagation in fluids and elastic solids. The formulation unifies the treatment of boundary conditions, prescribed displacement or stress at an interior surface, and brings together various results scattered throughout the literature. To illustrate application of the theory, square pulses in velocity and stress are specified at an interior surface and the flow variables in the resulting disturbances are calculated. The method of analysis and results are presented in a manner useful to research workers in this field as well as to physics students less familiar with the area of wave propagation.
A Sophomore Course in Experimental Physics
Authors: Carver G. P. , Scarl D. B.
Published: August 2005

A one-semester experimental physics course has been divided into two parts to enable students to plan and execute their own experiments. The first part of the course introduces some of the instruments and techniques of experimental physics through a set of programmed laboratories. The second part provides the opportunity to do a complete experiment from design to analysis without lab notes and with very little supervision.
Linearity of Electromagnetic Field Energy and Momentum
Authors: Chen Fong-Ching
Published: August 2005

It is shown that static electromagnetic fields have nonlinear energy and momentum due to the interaction between sources, while the apparent nonlinearity in energy and momentum densities of electromagnetic waves generated by noninteracting sources merely reflects a hitherto unsuspected degree of freedom of the energy-momentum four-tensor Tμν, which can undergo the following transformation without changing its physical meaning: Tμν→ T′μν = Tμν + Kμν, where the symmetric four-tensor Kμν is arbitrary except for the constraint δνKμν = 0. The force density fμ = δνTμν is preserved in this transformation. The implication of this transformation on fields everywhere satisfying the homogeneous wave equations is discussed.
Radiation and the Classical Electron
Authors: Newburgh R. G.
Published: August 2005

The radiated power emitted by an accelerated charge is relativistically invariant. This invariance imposes restrictions on the momentum change of the charge due to the radiation, which were first postulated by von Laue and are now shown to be more general. From these restrictions one can obtain the radiation reaction in a simple fashion. This approach clarifies the role of the acceleration or Schott energy in the emission of radiation and shows that its mass equivalent must be included in any discussion of particle momentum. This suggests the classical analog of a “dressed” particle.
Notes on “Image Methods in Electrostatics” (A Computer-Animated Film)
Authors: Blum Ronald
Published: August 2005

The computation and production of a computer-animated film is described. The film depicts a point charge slowly approached by (1) a grounded conducting sphere, and (2) an ungrounded (net charge equals zero) conducting sphere.
Density of States in a Sphere and Cylinder
Authors: Lambert R. H.
Published: August 2005

The density of states for the solutions to the wave equation are derived for a spherical and a cylindrical volume. The number of states per unit volume, in the limit of short wavelength, is known to be independent of the shape of the surface enclosing the volume. It is hoped the general result, first proved by Weyl, will appear more plausible if explicitly proved for several different shapes.
Polarization of Spin One-Half Particles
Authors: Fitelson Michael
Published: August 2005

The polarization of spin one-half particles may be calculated in two different ways. Either the polarization is evaluated directly by calculating the number of particles polarized in a given direction minus the number polarized in the opposite direction divided by the total number of particles, or with the density matrix approach. The purpose here is to discuss both of the above techniques in an elementary and self-contained fashion. Their equivalence is demonstrated by a calculation of polarization with each method for a general process.
Resource Letter BSPF-1. A Bibliography of Selected Physics Films
Authors: Riley William R.
Published: August 2005

Prepared at the request of the AAPT Committee on Resource Letters; supported by a grant from the National Science Foundation.

This is one of a series of Resource Letters on different topics, intended to guide college physicists to some of the literature and other teaching aids that may help them to improve course contents in specified fields of physics. No Resource Letter is meant to be exhaustive and complete; in time there may be more than one letter on some of the main subjects of interest. Comments and suggestions concerning the content and arrangement of letters as well as suggestions for future topics will be welcomed. Please send such communications to Professor Joel E. Gordon, Resource Letter Committee, Department of Physics, Amherst College, Amherst, Massachusetts 01002.

Additional copies: Available from American Institute of Physics, 335 East 45 Street, New York, New York 10017. When ordering, request Resource Letter BSPF-1 and enclose a stamped return envelope.
The Richtmyer Memorial Lecture—Particles, Accelerators, and Society
Authors: Wilson Robert Rathbun
Published: August 2005

Although there is a tendency for physicists to think of themselves as isolated from society, physicists are much involved in and are part of society. Physics contributes to society not only in a technical but also in an esthetic, social, and philosophical sense. Large physics projects, such as the 200-BeV accelerator, have recently had a direct influence on diverse social problems such as open housing and international cooperation.
Physical Properties of Particulate Radiation: A Student Experiment
Authors: Kanter M. , Carmon B.
Published: August 2005

Some well-known and important physical properties of alpha and weak beta particles are evaluated using air, helium, and aluminum as absorbers. In the method described the source-to-counter distance is left constant and the range is determined indirectly by changing the pressure of the gas inside the counting chamber. Other useful applications of this technique are discussed.
Is Charge Conservation Needed to Derive the Displacement Current?
Authors: Yano A. F.
Published: August 2005

It is shown that charge conservation is not necessary in deriving the displacement current in Ampere's law.
Approach to Radiative Equilibrium of Free Electrons through Čerenkov Emission and Absorption
Authors: Arunasalam V.
Published: August 2005

The approach to radiative equilibrium of a system of free electrons in a background medium whose index of refraction is larger than unity is studied in the light of the basic principles of elementary nonrelativistic quantum theory. It is shown that the radiative equilibrium arises as a consequence of a balance between Čerenkov emission (spontaneous plus the induced emission) and absorption of photons by the uniformly moving electrons. A coupled pair of equations, one describing the time evolution of the photon distribution function and the other describing the time evolution of the electron distribution function, is thus derived. The equation for the time rate of change of the electron distribution function reduces, in the classical limit, to a Fokker-Planck equation.
X-Ray Diffraction from Helices: Structure of DNA
Authors: Kittel C.
Published: August 2005

A review is given in elementary terms of the diffraction of waves from helices, with special reference to the structure of DNA. The essential features of the experimental results are discussed.
The Surf Skimmer
Authors: Edge R. D.
Published: August 2005

The simple principles of hydrodynamics which explain the unusual motion of a board skimming across shallow water are investigated to show the reason for the relatively slow loss of energy.
Nonlinear Gravity: A Discussion for Freshmen
Authors: Groom D. E.
Published: August 2005

A machine is constructed in which work is done on an external system as the distance between two gravitationally attracting point masses slowly decreases. A distant observer finds that the gravitational field of the two-mass system vanishes when the external work is equal to c2 times the input mass. The model is not to be pushed too far; but it does illustrate, by means of very elementary arguments, the essential nonlinearity of a correct gravitational theory and some interesting consequences of such a theory.
Resource Letter Rea-1 on Reactors
Authors: Michael Paul , Schermer Robert I.
Published: August 2005

Prepared at the request of the AAPT Committee on Resource Letters; supported by a grant from the National Science Foundation.

This is one of a series of Resource Letters on different topics, intended to guide college physicists to some of the literature and other teaching aids that may help them improve course contents in specified fields of physics. No Resource Letter is meant to be exhaustive and complete; in time there may be more than one letter on some of the main subjects of interest. Comments and suggestions concerning the content and arrangement of letters as well as suggestions for future topics will be welcomed. Please send such communications to Professor Joel Gordon, Chairman, Resource Letter Committee, Department of Physics, Amherst College, Amherst, Massachusetts.

Notation: The letter E after an item number indicates elementary level, useful principally for freshman liberal arts through sophomore physics courses; the letter I indicates intermediate (junior, senior) level; and the letter A indicates advanced material principally suited for senior, graduate study. An asterisk(*) indicates items particularly recommended for introductory study.

Additional copies: Available from American Institute of Physics, 335 East 45 Street, New York, New York 10017. When ordering, request Resource Letter Rea-1 and enclose a stamped return envelope.
Demonstration of the Ramsauer-Townsend Effect in a Xenon Thyratron
Authors: Kukolich Stephen G.
Published: August 2005

The anomalously small scattering of electrons near 1 eV energy by noble gas atoms may be easily demonstrated using a 2D21 xenon thyratron. This experiment is suitable for a lecture demonstration or for an undergraduate physics laboratory. The probability of scattering and the scattering cross section may be obtained as a function of electron energy by measuring the grid and plate currents in the tube.
Special Relativity in the Quantum Domain
Authors: Cohn Jack
Published: August 2005

The question is raised whether one can legitimately assume special relativity to be valid in the quantum domain. In partial answer to this query, it is demonstrated that, owing to the Heisenberg uncertainty relations, a very general type of detector is only able to resolve space time to a limited degree. To this same degree the notion of local simultaneity, which is basic to the special theory, is inexact.
Electrostatics Demonstrations with a Vibrating Reed Electrometer
Authors: Sears Francis W. , Stokstad Paul A.
Published: August 2005

A compact, stable, battery powered, transistorized vibrating reed electrometer has been designed specifically for use in lecture demonstrations and laboratory experiments. Some of the possible uses of the instrument are described.
Resource Letter OEPM-1 on the Ordinary Electronic Properties of Metals
Authors: Langenberg D. N.
Published: August 2005

Prepared at the request of the AAPT Committee on Resource Letters; supported by a grant from the National Science Foundation.

This is one of a series of Resource Letters on different topics, intended to guide college physicists to some of the literature and other teaching aids that may help them to improve course contents in specified fields of physics. No Resource Letter is meant to be exhaustive and complete; in time there may be more than one letter on some of the main subjects of interest. Comments and suggestions concerning the content and arrangement of letters as well as suggestions for future topics will be welcomed. Please send such communications to Professor Joel E. Gordon, Resource Letter Committee, Department of Physics, Amherst College, Amherst, Massachusetts 01002.

Notation: The letter E after an item number indicates elementary level, useful principally for high school and introductory college use; the letter I indicates intermediate (junior, senior) level; and the letter A indicates advanced material, principally suited for senior, graduate study. An asterisk (*) indicates items particularly recommended for introductory study.

Additional copies: Available from American Institute of Physics, 335 East 45 Street, New York, New York 10017. When ordering, request Resource Letter OEPM-1 and enclose a stamped return envelope.