bluuebunny/crossref_metadata_2025 huggingface dataset:
Graphical Solution for High-Frequency Electrostatic Deflection
Authors: Greenblatt M. H.
Published: August 2005

A graphical analog, which obeys the same equations as an electron beam during deflection, is described. The transverse displacement and velocity of the beam can be calculated from this analog, and certain details which are not obvious in the straightforward solution are apparent in the graphical-analog solution. A proposal for a charged-particle beam-velocity measuring device is made. This proposal is based on behavior revealed by the graphical-analog solution.
Presentation of Paul Kirkpatrick as the Oersted Medalist for 1958
Authors: Eaton Vernet E.
Published: August 2005

Remarks made by the Chairman of the committee on Awards in presenting Paul Kirkpatrick for award of the 1958 Oersted Medal in recognition of his notable contributions to the teaching of physics.
On Solutions of the Clock Paradox
Authors: Scott G. David
Published: August 2005

The nature of the clock paradox is discussed and three solutions are referred to: (a) length contraction, (b) Doppler effects, (c) world lines in chronogeometry. The Special Theory of Relativity gives a complete explanation of the problem and it is pointed out how the use of the General Theory provides merely an additional solution with no physically new aspects. Variations in the clock problem are introduced to make clear the essential asymmetry which exists between the two clocks.
Change of a Viscoelastic Sphere to a Torus by Random Impacts
Authors: Busse W. F. , Starr F. C.
Published: August 2005

When a small (< 2.5 g) ball of silicone putty was put into a vibrating cylinder, it first bounced around like a rubber ball. After some time the motion produced by the random impacts caused the sphere to change to a torus, and ultimately it broke up into smaller “dog bone” shaped pieces. If the size of the initial sphere was increased to 4–5 g or more, the spherical shape remained stable for many hours. When the initial shape was changed from a sphere to a cube to a prism, the minimum critical size that would form a stable sphere increased from about 3 to 6 to 20 g, respectively. The formation of the torus is due to the combined effect of the spectrum of relaxation times of the material, the short time of impacts with the wall, and the tendency of a body in free flight to rotate around the axis having the highest moment of inertia.
Introduction to Apparatus Drawings
Authors: Kelly W. C.
Published: August 2005

A series of articles containing construction notes and drawings of apparatus for teaching undergraduate college physics will appear in the American Journal of Physics beginning with this issue. The present paper reviews the origin and the objectives of the Apparatus Drawings Project.
It Is Important to Know What Questions to Ask
Authors: Miller Julius Sumner
Published: August 2005

Our principal concern in the study of physics is: how does Nature behave? The answer is best gotten by finding the answers to an array of simpler fundamental questions. It is important, therefore, to know what questions to ask. This paper bears on several instructional points of view: (1) in the professor's narration there is too much communication of fact and too few of the right kinds of questions asked; (2) textbook problems do not cultivate the habit of asking questions; (3) there should be more general analytic exercises which permit the examination of limiting cases, for in limiting cases lies the heart of the inquiry; (4) demonstration experiments must be accompanied by appropriate questions. Illustrative examples point up the argument.
Flash Period of 1958 Delta I
Authors: Carr Percy H. , Stewart Robert M. , Senne Joseph H.
Published: August 2005

Careful observation of the flash period of the artificial satellite, 1958 Delta I (the rocket ease of Soviet Sputnik III), was made at Ames, Iowa, from July 21 through November 29. The flash period increased steadily during this time until approximately one-half week before fall-in. This indicated a slowdown in the rate of tumbling of the rocket case. During the last few days of life the flash period decreased, indicating a speedup in tumbling rate. What causes this change? Future satellite observers are urged to observe this phenomenon to see if it is general.
Extending the Lorentz Transformation by Characteristic Coordinates
Authors: Jones Robert T.
Published: August 2005

The problem considered is that of rectilinear motion with variable velocity. The paper gives, by an elementary construction, a system of coordinates which is conformal in a restricted region near the axis of the motion. In such coordinates the velocity of light remains invariant even for observers moving with variable velocity. By a particular choice of the scale relation the restricted conformal transformations can be made to reduce to the Lorentz transformation everywhere in the case of constant velocity and locally in the case of variable velocity.
Graphical Representation of Some Electrical Potential Fields
Authors: Heid Roland L.
Published: August 2005

Electric potential fields were plotted by means of field mapping paper and probes. The paper was cut into different patterns simulating various electrical circuits. The results present to the student a striking illustration of the potential distributions in these circuits.
Conducting Analogs of a Magnetic Field
Authors: Barker J. R.
Published: August 2005

The distribution of electric current in a conducting medium has a close analogy with the distribution of magnetic flux in a geometrically similar magnetic field. There is a second form of the analogy, when the field is two-dimensional, in which the electric equipotentials correspond with the magnetic flux lines. These analogies are closely examined with a view to demonstrating their value in an undergraduate teaching program.
Light-Pressure Tube
Authors: Neher H. V.
Published: August 2005

A device for demonstrating the pressure of light is here described. With present-day techniques it is not only possible to produce a gas pressure sufficiently low to reduce the radiometer effects to a negligible value compared with the light pressure effect, but it is also possible to maintain such a vacuum in a sealed-off tube for long periods of time.
Efficiency of Thermoelectric Devices
Authors: Gross Eric T. B.
Published: August 2005

The known expressions for various efficiencies of thermoelectric energy converters can be so modified that the Carnot efficiency ηc of the ideal heat engine cycle appears as one of two significant parameters. The other parameter ZT (Z = figure of merit, T = hot spot temperature  in °K) is a significant characteristic of the thermoelectric material used in the device. Using these parameters leads to a realistic evaluation of presently possible efficiencies under ideal conditions.
Some Properties of Alkali Halide Crystals
Authors: Braun E. A.
Published: August 2005

The cohesive energy of alkali halide crystals can be approximated by treating it as arising from purely polar interactions. An attractive Coulomb potential and a repulsive overlap potential are the only terms that need to be considered. The phenomenon of coloration of alkali halides is described with particular emphasis on the mechanisms involved. As an example of luminiscence, the luminescent process in T1 activated alkali halides is discussed.
Radio Astronomy
Authors: Laffineur Marius
Published: August 2005

The nature, reception, and measurement of extra-terrestrial radio waves are described, followed by a discussion of the correlation of radio objects with optical objects. Radio emission from hydrogen, the sun, and the planets is discussed. The characteristics and resolving power of radio telescopes are explained. A consideration of the educational aspects of radio astronomy concludes the paper. Two appendixes discuss synchrotron radiation and galactic range finding.
Team Approach to Education
Authors: Zacharias Jerrold R.
Published: August 2005

The Response of the Oersted Medallist to the American Association of Physics Teachers, February 2, 1961.
Derivation of the Displacement Current from the Biot-Savart Law
Authors: Bierman Arthur
Published: August 2005

A calculation of the curl of B starting with the Biot-Savart law leads directly to the inclusion of the displacement current into Maxwell's equations; one must assume slowly moving charges, slowly varying currents, and a neglect of the radiation field at large distances and after a long time.
Von Neumann's Hidden-Parameter Proof
Authors: Albertson James
Published: August 2005

Because the mathematical form of von Neumann's hidden-parameter proof is not well known, its scope has sometimes been unjustifiably narrowed by commentators. The proof is here reproduced in the more familiar Dirac calculus and its precise import made clearer. In particular, it is emphasized that the proof proceeds independently of both the basic statistical assumption of quantum mechanics: 〈R〉av = 〈φ|R|φ〉, and the extension of this assumption to mixtures: 〈R〉av = Tr(UR), where U = Σn|φn〉wn〈φn|. Mention is also made of some recent criticisms of the von Neumann proof.
Definition of Macroscopic Electrostatic Field
Authors: Kaufman Allan N.
Published: August 2005

It is frequently stated that the electric field of the macroscopic Maxwell equations is the mean of that of the microscopic Maxwell equations. By “mean” is meant either a volume average or a statistical average, the result being the same. In this paper, the electrostatic field is considered, and it is shown that the mean microscopic field is not appropriate for use in the concept of dielectric constant. A suitable definition of macroscopic field is discussed, and it is shown that it differs from the mean microscopic field in a nonuniform medium.
Geometrical Approach to the Theory of Probability
Authors: McLachlan Dan , Chamberlain L. L.
Published: August 2005

The purpose of this paper is twofold: first, we wish to present an interesting geometrical approach to the derivation of some familiar equations in the theory of probability, and second, we wish to use this newer approach for extending the scope of the equations. Particularly, we wish to extend the well-known problem of how many ways there are of distributing m identical objects among n numbered boxes with no more than one in each box to the problem of distributing the m objects in n boxes with no more than M in each box. The solution of this more general problem of M as the limiting number per box is expressed as a mathematical series involving factorials.
Further Remarks on the Zeroth Law
Authors: Turner Louis A.
Published: August 2005

The zeroth law of thermodynamics is shown to be a consequence of the absence of appreciable long-range forces between different portions of bodies of the kind usually under consideration in thermodynamic discussion. Revisions of the arguments given in an earlier paper are suggested in order to meet objections raised by Thomsen.
A Simplified Treatment of the Quantum-Mechanical Scattering Problem Using Wave Packets
Authors: Hobbie Russell K.
Published: August 2005

This paper presents a treatment of quantum-mechanical scattering suitable for a senior level course in modern physics. The entire treatment is based on the use of wave packets instead of unrealistic plane waves. The asymptotic behavior of the scattered wave packet is derived from physical considerations, and the Born approximation is then obtained for a wave packet in a manner which displays the details of the scattering process.
Coefficients of Diffusion, Viscosity, and Thermal Conductivity of a Gas
Authors: Desloge Edward A.
Published: August 2005

The coefficients of diffusion, viscosity, and thermal conductivity of a gas are derived in first approximation following the method of Maxwell and Chapman. The derivation differs from previous derivations primarily in the expression and evaluation of the various collision integrals.
Kalantaroff Dimension System
Authors: Kinitsky V. A.
Published: August 2005

The system of dimensions that was proposed by Kalantaroff in 1929 is discussed and its advantages are pointed out. In this system electric charge and magnetic flux are taken as fundamental, in addition to length and time. Tables of the dimensions of commonly used physical quantities are included.
Intermediate Courses in Physics
Authors: Condon E. U.
Published: August 2005

If we are to improve the preparation of physics majors, in keeping with the needs of the times and with the improved preparation that students in increasing numbers will be bringing from their high schools, we must decide on what parts of physics are most important. It is suggested that our courses must pay greater attention to phenomena and less to mathematical formalism. Specific suggestions about the ways in which courses in mechanics, electricity and magnetism, optics, atomic and nuclear physics, and thermodynamics can be modified to accomplish this are given.
Retardation and Diffraction Aspects of the Conduction of Heat in Solids
Authors: Alzofon Frederick E.
Published: August 2005

The concept of retardation of phase and energy propagation, borrowed from analyses used in physical optics, is applied to the analysis of heat conduction in solids. Analogies between physical optics and heat conduction in solids are pointed out and these are given a general interpretation in terms of a superposition of traveling waves. It is shown that interference effects may occur in the propagation of heat in a solid. Some of the notions of physical optics are then applied to the analysis of heat conduction in solids. A simple experiment demonstrating interference of traveling waves in heat conduction is analyzed. An analog to the Kirchhoff formula, exhibiting the role of diffraction effects in the conduction of heat in solids, is derived.
Magnetic-Dipole Models
Authors: Tellegen B. D. H.
Published: August 2005

A recent book rejects the amperian-current model of a magnetic dipole and accepts the magnetic-charge model, because the first model would lead to inconsistencies in the interpretation of Poynting's theorem. It is shown that the inconsistencies are only apparent. The choice between the two models should be based on measurement of the force on a magnetic dipole, which, in nonstationary cases, is different for the two models.
Homogeneous Nucleation of Vapor Condensation. II. Kinetic Aspects
Authors: McDonald James E.
Published: August 2005

In the absence of foreign nucleants, phase transition from vapor to liquid is blocked by a free-energy barrier implicit in the appearance of new surface when embryos of the new phase start to form. Drawing upon thermodynamic relationships discussed in Part I, Part II here summarizes the kinetics of the homogeneous nucleation process for the case of the vapor-to-liquid phase transition. Emphasis is placed upon physical interpretation of the mathematical model used to obtain a nucleation rate equation for the unbalanced steady-state case.
Moduledra Crystal Modules. A Teaching and Research Aid in Solid-State Physics
Authors: Loeb A. L. , Pearsall G. W.
Published: August 2005

Tetrahedral and octahedral building blocks have been devised for the construction of a large variety of crystal structures. Since these blocks can be stacked without special fasteners, they can be rearranged conveniently in order to demonstrate underlying relationships between various crystal forms. Their use in portraying a number of different structures is discussed.
Forces and Fields in Special Relativity
Authors: Ganley W. P.
Published: August 2005

In most undergraduate courses that include Special Relativity, the force transformation laws are not usually discussed. Since force is an extremely fundamental physical concept, the suggestion is made that the force transformations always be included with the discussion of the transformations for mass, length and time. Two examples of force transformations applied to electromagnetic systems are described in detail, along with an elementary derivation of the force transformation laws that requires no formal calculus.
Resource Letter MB-1 on Experiments with Molecular Beams
Authors: Zorn Jens 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 Arnold Arons, Chairman, Resource Letter Committee, Department of Physics, Amherst College, 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 MB-1, and enclose a stamped return envelope.
William Rowan Hamilton, Michael Faraday, and the Revival of Boscovichean Atomism
Authors: Kargon Robert
Published: August 2005

Although the contributions of Sir William Rowan Hamilton to mathematical physics are well known, the physical framework for some of his major endeavors has long been neglected. A philosophical idealist, Hamilton preferred to base his conception of physical reality upon “force” or “power” rather than “matter.” Hamilton was thus drawn to the atomism of Roger Boscovich who replaced hard atoms with point centers of force. Hamilton saw his mathematical contributions as the completion of the Boscovichean model, just as Lagrange, in some sense, completed the work of Newton. Hamilton agreed in his view of matter with Michael Faraday who likewise was drawn to Boscovichean atomism but who saw it mainly in the light of his electrical and chemical researches. Joseph Henry criticized Boscovichean atomism but really was criticizing Faraday's presentation, which omitted the concept of inertia.
The Pythagorean Numbers in Vector Problems
Authors: Lavatelli Leo
Published: August 2005

A scheme for generating all the primitive triplets of integers (a, b, c) that satisfy the Pythagorean relation a2+b2 = c2 is pointed out, and some interesting properties of these triplets are noted. These triplets are useful in the design of mechanics problems where right triangles other than the three well-known ones are desired.
Resource Letter PhM-1 on Philosophical Foundations of Classical Mechanics
Authors: Hesse Mary
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 Arnold Arons, 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 PhM-1 and enclose a stamped return envelope. A small booklet containing reprints of some of the fundamental references will soon be available for purchase from the American Institute of Physics.
A Versatile Ballistic Pendulum
Authors: Barton R. W.
Published: August 2005

The design and use of a versatile and inexpensive ballistic apparatus for the undergraduate laboratory is described.
Derivation of the Lorentz-Transformation Equations without a Linearity Assumption
Authors: Weinstock Robert
Published: August 2005

The Lorentz-transformation equations are derived, with the aid of elementary calculus, from the basic kinematical assumptions of special relativity without the use of any linearity assumption.
Experiences with Solder Glass and Students
Authors: King John G.
Published: August 2005

Over the past few years experience has accumulated with student use of solder-glass techniques for the construction of simple vacuum tubes for doing experiments with electrons, ions, and atoms. The details of a freshman seminar are discussed, and examples of the work of the students, including sample laboratory reports and data are given. The success of the seminar indicates that the technique can be extended to handle large groups of students.
Sealing with Solder Glass
Authors: Dalton Robert H.
Published: August 2005

A discussion is given of the advantages and limitations of the techniques of sealing with solder glasses, of the characteristics which a glass must possess to be suitable for solder sealing, and of the properties of some of the available solder glasses.
Speed and Kinetic Energy of Relativistic Electrons
Authors: Bertozzi William
Published: August 2005

Using a Van de Graaff electrostatic generator and a linear accelerator, the speeds of electrons with kinetic energies in the range 0.5–15 MeV are determined by measuring the time required for the electrons to traverse a given distance. The measurements show the existence of a limiting speed in accord with the results of special relativity. The kinetic energy, determined by calorimetry,verifies that an electric field exerts a force on a moving electron in its direction of motion that is independent of its speed.
The Relation Between Classical and Quantum Mechanics
Authors: Rosen Nathan
Published: August 2005

It is pointed out that, if classical mechanics is to be regarded as a limiting case of quantum mechanics, then it must admit superpositions of states, which are generally regarded as unacceptable. To avoid this it is proposed that classical mechanics be described by a nonlinear equation which is equivalent to the Hamilton-Jacobi equation and is not always the limit of the Schrödinger equation. It is conjectured that the transition from the wave-mechanical equation to the classical equation is characterized by a mass m0 = ħc/γ12 ≈ 10−5g. This nonlinear equation may help one to understand the process of measurement of a quantum-mechanical system by means of a classical measuring instrument.
The “Radial Kinetic Energy” Term in the Schrödinger Equation for a Central Force
Authors: Crawford Frank S.
Published: August 2005

A straightforward derivation is given for the Hermitian operator pr ≡ 1r ħi δδrr corresponding to the radial component of linear momentum in the central force problem. The purpose is purely pedagogical; we believe that the radial term of the Schrödinger equation in spherical coordinates is more comprehensible when it appears in the form (pr2/2m)ψ = [(1r ħi δδrr)2/2m]ψ than when it appears, as it does in most textbooks, in the form −ħ22mr2 δδr[r2δδr]ψ. The latter expression is usually arrived at by a tedious transformation of variable done “in the appendix”; instead one may derive pr with a minimum of algebra and with the focus where it belongs, on the concepts of quantum mechanics.
Nonsymmetrical Property of Magnetic Monopoles
Authors: Strax N.
Published: August 2005

It is shown that the sign of a magnetic monopole can be given an absolute significance, and not merely a relative significance. This is a consequence of the following three properties of our universe: (a) the existence of electromagnetism, (b) the existence of parity nonconserving weak interactions, and (c) the nonsymmetry with respect to the two directions of time which is manifest in the second law of thermodynamics and the expansion of the universe.
Phase-Space Occupation of Electron, Proton, and Photon Beams
Authors: Katz Robert , Curnutte Basil
Published: August 2005

The intensities of known electron, proton, and photon beams are compared to the intensity of a saturated beam of fermions, providing direct experimental evidence for the boson nature of photons.
Thermodynamic Derivatives without Tables
Authors: Thomsen John S.
Published: August 2005

A simple, concise method is presented for deriving any desired thermodynamic first derivative in terms of a minimal basic set. The method is given in detail for a two-degree-of-freedom system, specifically a homogeneous fluid. The variables involved, including thermodynamic potentials, are briefly reviewed and the Maxwell relations derived. Differentials of all variables are expressed in terms of those of p and T with the use of a basic set of three partial derivatives. A four-step method is then stated for deriving any desired first derivative from these expressions; three examples are presented as illustrations. The Jacobian formalism is given for comparison at appropriate points, but not otherwise used. Finally, a natural, straightforward extension of the method to an N-degree-of-freedom system is outlined.
Resource Letter EEC-1 on the Evolution of Energy Concepts from Galileo to Helmholtz
Authors: Brown Theodore M.
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 Arnold Arons, 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 EEC-1 and enclose a stamped return envelope.
Mechanics Experiments using Modified PSSC Apparatus
Authors: Shuter W. L. H.
Published: August 2005

Low-cost modifications we have made to standard PSSC apparatus which greatly facilitates its use by large laboratory classes are described, and an outline is given of mechanics experiments we have designed for first-year physics-major students using this modified apparatus.
Correction to the Rydberg Constant for Finite Nuclear Mass
Authors: Coffman Moody L.
Published: August 2005

If the problem of the hydrogen-like atom is done with the assumption that the nucleus is at rest, the resulting energy levels are proportional to the Rydberg constant for infinite mass. It is traditional to obtain the Rydberg constant for finite mass of the nucleus by a simple substitution of the reduced mass of the system for the electron mass in the expression for the Rydberg constant for infinite nuclear mass. Realization that such a substitution (which is drawn from classical mechanics) does not give a correct transformation to the center-of-mass coordinate system in the case of charged particles, leads one to significant corrections for the Rydberg constants of finite nuclear masses. The corrections are drawn from classical, non-relativistic physics. Also, an interesting conjecture about the energy levels of hydrogen-like atoms, under the assumptions of Bohr theory and classical physics, is obtained.
The Synchrodropper—A Versatile Tool
Authors: Gunn Ross
Published: August 2005

A usefully stable synchronous water dropper having many uses in demonstration and laboratory work is described. A tuned leaf spring is driven by ordinary 60-cps alternating current power and arranged to dispense serially drops of constant size. By observing these drops with an electronic flash or synchronous motor driven stroboscope during either their free fall or collision, demonstration experiments and measurements can be made. A design for producing uniform drops with a minimum of “jitter” and operating difficulty is given together with appropriate methods for assuring reliable performance.
Some Uses of Hyperbolic Velocity Space
Authors: Boyer R. H.
Published: August 2005

This paper deals with the definition and properties of the velocity space of special or general relativity. The metric naturally induced by the enveloping space-time is that of a space of constant negative curvature which is referred to here as a 3-dimensional Lobachevsky space. Our purpose is to show how this notion can simplify or reinterpret ideas of relativistic kinematics. Supplementing the more familiar applications, three others are given here which make essential use of the curvature, namely to the derivations of aberration, Thomas precession, and the forms of relativistic collision invariants.
Relativistic Rigid Bodies and the Uncertainty Principle
Authors: Hart Robert R.
Published: August 2005

Special relativity excludes the existence of rigid bodies, since such bodies can be used to transmit signals instantaneously. It is pointed out that the uncertainty principle requires that a force of order hc/l2 must be available if a rigid body of length l is to be used to produce such a violation of relativistic causality; a condition which is particularly stringent in the domain of elementary particles. Thus, where a force of this magnitude is not available, the treatment of bodies of length l as rigid may be valid.
Locations of Neutron Single Particle States
Authors: Cohen Bernard L.
Published: August 2005

The meaning and importance of single particle (SP) states in nuclear shell theory is outlined, and the method of determining them from studies of deuteron stripping reactions is described. The results on locations of SP states are summarized and analyzed to obtain information on the shell theory potential. The depth of this potential is found to have a symmetry energy dependence somewhat weaker than that for optical model potentials for protons. The “self-binding energy,” a lowering of the energy of a SP state as it fills, plays an important role; its magnitude is determined and an empirical expression for it is given. Special neutron-proton interactions must be taken into account in a few cases. The spin-orbit potential seems to be of the form f(r)σ·l where f(r) = r−1dV/dr; a volume or a simple surface force are excluded. The explicit l-dependence of SP energies is much less than that commonly used, and indicates that the potential is much closer to an oscillator than to a square well in shape. The spacings between major shells require a velocity dependent potential corresponding to an effective mass of 1.3 times the nucleon mass. The shift of SP energies with A indicates that the well gets shallower with increasing A; the depth change is about 5.8 MeV from Ca to Pb. Locations of neutron giant resonances are estimated.
On the Degeneracy of the Two-Dimensional Harmonic Oscillator
Authors: Dulock Victor A. , McIntosh Harold V.
Published: August 2005

A further study of the degeneracy of the two dimensional harmonic oscillator is made, both in the isotropic and anisotropic cases. By regarding the Hamiltonian as a linear operator acting through the Poisson bracket on functions of the coordinates and momenta, a method applicable generally to bilinear Hamiltonians, it is shown how all possible rational constants of the motion may be generated. They are formed from eigenfunctions of the Hamiltonian which are linear combinations of the coordinates and momenta, and which belong to negative pairs of eigenvalues. Canonical coordinates, which may be visualized geometrically for the isotropic oscillator in terms of the Hopf mapping, place the symmetry group responsible for the accidental degeneracy clearly in evidence. Surprisingly, one finds that the unitary unimodular group SU2, is the symmetry group in all cases, even including that of an anisotropic oscillator with incommensurable frequencies. The lack of a quantum-mechanical analogy in the latter case is due to a lack of the necessary transcendental roots of the operators involved in attempting to use the correspondence principle, rather than to the lack of a symmetry group for the classical problem.
Quantum Fact and Fiction
Authors: Landé Alfred
Published: August 2005

The fact is that, beside the two quantum rules for energy and angular momentum, there is a third analogous rule for the linear momentum, established by W. Duane in 1923. Though this rule is generally accepted, there is no trace of recognition in the literature that it yields a consistent unitary particle explanation of all those phenomena of diffraction and coherence, e.g., of the two-slit experiment, which allegedly can be accounted for only by the fiction of a dual nature of matter, with transmutation of particles into waves and back into particles again. The usual method of solving this dilemma has admittedly been that of “refining the language of physics,” beginning with replacing the physical idea of a forth and back transformation by the term “dual manifestation,” thereby shunning any “real” constitution of matter, which then requires a specially adjusted philosophy of knowledge. In contrast, the quantum rule for the linear momentum solves the apparent contradictions in a physical manner without alternating manifestations. It introduces a great simplification which should also influence the method of teaching the theory. The purpose of the present article is to give due credit to the American pioneer of quantum mechanics, W. Duane, whose contribution to solving the duality paradox is a shining example of the scientific method, in contrast to the purely semantic approach in vogue for more than a generation.
Some Developments in Generalized Classical Mechanics
Authors: Koestler Judith G. , Smith Joseph A.
Published: August 2005

The generalized classical mechanics of Borneas is extended to include familiar topics in an advanced course in classical mechanics. Hamilton's equations of motion are derived in a generalized form. Interesting features of momenta related to, but not conjugate to generalized cyclic coordinates are developed. Generalized Poisson and Lagrange brackets are defined and the subjects are developed. The inverse nature of generalized Poisson and Lagrange brackets is proved, and generalized equations of motion are expressed using Poisson bracket notation.
A Student Radiometer
Authors: Hager Nathaniel E.
Published: August 2005

An easily constructed differential radiometer is described which can be calibrated analytically from its geometric and physical parameters. An estimated 3% accuracy is achieved using common handbook values for the physical parameters, and the accuracy of the calibration is confirmed by experiment. The instrument measures net thermal radiation exchanged between surfaces near normal room temperature. It responds quickly to changes in incident flux and reaches equilibrium within about 1 min. It is sufficiently stable and rugged to be considered for student experiments and for demonstration lecture work. A number of elementary experiments are described which use the radiometer to demonstrate the behavior of long wavelength infrared radiation and to determine its interaction with materials.
Resource Letter SL-1 on Science and Literature
Authors: Nicolson Marjorie
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 in 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. Such communications should be sent to Professor Arnold Arons, Chairman, Resource Letter Committee, Department of Physics, Amherst College, Amherst, Massachusetts.

Notation: 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 SL-1 and enclose a stamped return envelope.
Noninteraction between Static Electric and Magnetic Fields
Authors: Kelly Edward M.
Published: August 2005

If an electrostatic field and a magnetostatic field are assumed to be physically of the same species and added together vectorially, after being expressed in common units, the interaction energy between fields is shown to vanish. Noninteraction of the fields, that is, the failure of static charges to have macroscopic influence on stationary magnets, is therefore not a sufficient condition to establish that they are of different species, but may be a result of mathematical form.
Three Problems on Random Events
Authors: Bell R. E.
Published: August 2005

Three simple problems concerning random events are proposed and discussed. In each problem some unexpected feature emerges, and an attempt is made to clarify the results in the light of actual practice.
Symmetry, Uniqueness, and the Coulomb Law of Force
Authors: Shaw Ronald
Published: August 2005

Some arguments from symmetry, frequently occurring in elementary electricity, are criticized, and the importance of the uniqueness theorem in electrostatics is stressed. It is conjectured that for a 1/rn law of force a uniqueness theorem only holds in the case n = 2. The problem is posed of finding a solution to any electrostatic problem whatsoever (involving conductors) if the law of force is not the Coulomb law.
Concerning the Number of Independent Variables of the Classical Electromagnetic Field
Authors: Katz E.
Published: August 2005

The classical electromagnetic fields are usually described by six independent functions of space and time, namely the three components of the electric field and the three components of the magnetic field, satisfying Maxwell's equations. On the other hand it is well known that all observable effects of these fields can be derived from five components of the electromagnetic stress-energy tensor. Consequently the usual description contains one superabundance, that can be described by one parameter φ which cannot be measured experimentally but must be fixed by an arbitrary convention. Implicit conventions concerning φ, underlying the usual approach to electromagnetic fields tend to obscure the understanding and should be replaced by an explicitly stated convention. It is recommended that this convention be that φ be defined zero for electrons.
Translational Symmetry and Zero-Mass Excitations
Authors: Cronin J. A.
Published: August 2005

For a simple class of Hamiltonians of a continuous medium it is shown that the condition of translational invariance implies a zero-energy gap in the excitation spectrum. It is also shown that because of translational symmetry a spurious state of zero energy and momentum exists for an electron plasma in a positive background. This spurious state becomes massive when translational symmetry is broken.
The Parity Operator and the Fourier Transform Operator
Authors: Epstein Saul T.
Published: August 2005

Explicit formulas, in terms of coordinate and momentum operators, are given for the parity operator and the Fourier-transform operator.
Bifilar Pendulum—An Experimental Study for the Advanced Laboratory
Authors: Then John W.
Published: August 2005

This study is concerned with various forms of bifilar suspensions and a quantitative comparison of experiment with theory. The various forms of the equations and the surprisingly simple form taken by some are considered. Moments of inertia are obtained experimentally and compared with the calculated moments from the theory.
Nuclear Stripping Reactions
Authors: Ivash Eugene V.
Published: August 2005

The theory of nuclear stripping reactions is presented in a simple fashion. It is suggested that inclusion of the subject of stripping reactions in the graduate quantum mechanics curriculum may be of great value to the student.
Units for Atomic and Subatomic Physics
Authors: Barkas Walter H.
Published: August 2005

The consequences are examined of setting ħ = 1 and c = 1, while retaining the electron volt. The system of units thus defined is simple and practical for atomic and subatomic physics. A convention is also suggested which permits any quantity to be expressed by a number near unity. Trial teaching with such units is suggested.
Review of a New Course in Physics
Authors: Kumar Kailash
Published: August 2005

The Feynman Lectures on Physics, Vol. 1, are reviewed to illustrate some features common to many new physics courses.
Is High-School Physics a “Waste” for College Preparation?
Authors: Renner John W. , Whitaker Robert J. , Bautista Leticia B.
Published: August 2005

A survey was conducted to determine the type of introductory physics courses that is being offered in college physics departments and whether special courses are offered for those students who have completed high-school physics. Analysis of the questionnaires indicates that very few colleges or universities offer special consideration to these students. Representative comments made by the respondents to the survey are given, and some of the problems which are raised are discussed. Suggestions are made for future study needed to arrive at possible solutions to these problems.
Advanced Mössbauer-Effect Experiments
Authors: Haskins J. R.
Published: August 2005

This is a report on various possible student experiments with the Mössbauer effect beyond the basic resonance experiments. The information in this report was collected on visits to various research and teaching laboratories in which Mössbauer experimentation is carried on. The visits were arranged and sponsored by the AAPT-AIP Center for Educational Apparatus in Physics, which is supported by the National Science Foundation. F. E. Christensen is the director of the Apparatus Center.
Computers and the Nonscience Major
Authors: Bork Alfred M.
Published: August 2005

A natural science course for nonscience majors used the digital computer in teaching classical mechanics. The advantages of using the computer in physics courses for both science and non-science majors are discussed.
New Atwood's Machine Attachment
Authors: Chen Henry S. C.
Published: August 2005

A new Atwood's machine attachment has been designed in which one side of the system consists of a drum around which the string is wrapped so that the drum rotates as it falls. The other side of the system consists of a falling body, whose mass can be varied. Two sparktimer records are taken, one for the drum, and one for the falling body. Data taken are used to verify the law of motion of the mass center and the law of motion about the mass center.
X-Ray Diffraction and the Bragg Law
Authors: Elton L. R. B. , Jackson Daphne F.
Published: August 2005

Elementary textbooks frequently make assumptions, which are difficult to justify, in their derivations of Bragg's law. The present proof attempts to avoid these and yet to remain elementary.
Resource Letter SAP-1 on Subatomic Particles
Authors: Swartz Clifford 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 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, Chairman 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 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 SAP-1 and enclose a return envelope.
Quantum-Mechanical Tunneling
Authors: Fermor J. H.
Published: August 2005

An elementary method is given for the exact determination of the quantum mechanical transmission and reflection coefficients for a rectangular one-dimensional potential barrier. The method also finds application in approximate solutions for multistep barriers.
The Microscopic Interpretation of Entropy
Authors: Frisch David H.
Published: August 2005

The Boltzmann expression S = k ln Weq is developed from the macroscopic definition S ≡ ∫dQ/T and the quantum-mechanical interpretations of heat and work.
Dynamic Elastic Constants
Authors: Omar M. A.
Published: August 2005

A simple derivation of the dynamic elastic constant in a monatomic and a diatomic chain is given. The oscillation frequency for these lattices is then simply derived from the equations of the harmonic oscillator. The propagation velocity is given directly.
A Versatile, Inexpensive Neutron Howitzer
Authors: Rawls W. S. , Voss H. G.
Published: August 2005

A neutron howitzer has been constructed in the physics department shop, using readily available materials and commonly used tools. The neutron howitzer is versatile, of quality construction, safe for student use, and low in cost.