bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical theorem and beyond
Authors: Newton Roger G.
Published: March 2005

The history of the so-called optical theorem in scattering theory is traced from its beginning over 100 years ago to recent applications of its generalizations.
Electromagnetic fields in rotating superconductors
Authors: Rystephanick R. G.
Published: March 2005

Electric and magnetic fields induced inside rotating superconductors are explained in terms of the familiar centrifugal and Coriolis forces.
Electric field reversal and amplification in a low-pressure high-frequency gas discharge
Authors: Harmon Gerald S.
Published: March 2005

Under certain conditions, the presence of a sheath separating electrodes from the body of a plasma can give rise to a reversal of the electric field direction in the discharge. In addition, there may be a considerable gain in the strength of the field. This paper deals with a simplified model of the effect that can be employed as a rather interesting problem in an undergraduate electricity and magnetism course.
Effect of the mass of the cord on the period of a simple pendulum
Authors: Armstrong H. L.
Published: March 2005

It is well known that, when a weight hanging on a spring oscillates up and down, the spring, owing to its mass, has some effect on the motion and, in particular, on the period. Both exact and approximate solutions to that problem have been given. Likewise, the cord of a simple pendulum, because of its mass, has some effect on the motion and on the period. The solution to the problem is investigated here. It leads to a rather complicated equation involving Bessel functions of both kinds. However, it is possible to find simpler approximations which are likely to be legitimate in practice. Also, the results obtained are compared with some other arrangements, which seem physically to have some resemblance to the cord and pendulum bob, and which can be solved fairly readily.
New look at the Ptolemaic system
Authors: Brehme Robert W.
Published: March 2005

The Ptolemaic system of planetary motions is examined in detail in order to demonstrate its direct kinematical connection with a heliocentric system. Ptolemy’s planetary parameters are shown to be in good agreement, upon transformation, with modern values.
Subharmonics and ultraharmonics in the forced oscillations of weakly nonlinear systems
Authors: Prosperetti Andrea
Published: March 2005

The characteristics of subharmonic and ultraharmonic modes appearing in the forced, steady-state oscillations of weakly nonlinear systems are considered from the physical, rather than mathematical, viewpoint. A simple explanation of the differences between the two modes, and in particular of the threshold effect usually exhibited by subharmonic oscillations, is presented. The fundamental resonance in the case of weak excitation is also briefly considered.
Resource Letter SE-1: Solar energy
Authors: McDaniels D. K. , Throop M. J.
Published: March 2005

Prepared at the request of the AAPT Editorial Board for Resource Letters. This is one of a series of Resource Letters on different topics intended to guide college physicists, astronomers, and other scientists to some of the literature and other teaching aids that may help improve course contents in specified fields. 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 on these materials as well as suggestions for future topics will be welcomed. Please send such communications to Professor Aaron Owens, Editor, Resource Letter Board, Department of Physics, Lake Forest College, Lake Forest, IL 60045.

N o t a t i o n: The letter E after an item 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 level.

R e p r i n t s: When ordering, request Resource Letter SE-1. Enclose 75 cents per copy (not in stamps) together with a stamped, self-addressed envelope and send to Executive Office, American Association of Physics Teachers, Graduate Physics Building, SUNY at Stony Brook, Stony Brook, NY 11794.
Functional differential equations in physics
Authors: da Costa R. C. T. , Lobo R.
Published: March 2005

A brief summary of the mathematical properties of functional differential equations is followed by two examples, taken from classical dynamics, which clarify the meaning of the peculiar initial conditions required for their solutions. The extensions of these solutions forwards and backwards in time are also discussed, both in the theory and in the examples.
Electronic nuclear lifetime experiment for the senior laboratory
Authors: Shapiro Mark H.
Published: March 2005

As part of a senior level course in nuclear laboratory techniques, the lifetime of the 482.0-keV level of 181Ta has been measured by the differential coincidence method in order to illustrate some of the principles involved in a fast timing experiment. An inexpensive source for the experiment was prepared by irradiating natural hafnium metal in a neutron howitzer for a period exceeding 90 days. With simple detectors and electronics, a time resolution width of better than 3.5 nsec was obtained. Within a few lab periods the students were able to align the system and obtain a delayed coincidence time spectrum from which they were able to determine the lifetime of the 482.0-keV level to within ±15% of the accepted value, 10.8 nsec.
’’The Age of Newton’’: An intensive physics and mathematics course
Authors: Calvert J. B. , Tuttle E. R. , Warren Peter
Published: March 2005

’’The Age of Newton’’ is an intensive course in mathematics (calculus), mechanics, optics, and astronomy directed mainly toward nonscientists. Although it introduces the subjects in a consciously historical context, it is a course in—not merely about—science and mathematics. The course is divided into a central lecture series, at which guest lecturers may participate, a series of topical tutorial lectures, and four workshops or laboratories, one each in mathematics, mechanics, optics, and astronomy. Original sources, notably Newtons’s Optics and Galileo’s Two New Sciences, are used as far as practicable. Special apparatus was built to allow the performance of the experiments described by Newton and Galileo, in addition to modern experiments with air tracks, spectroscopes, lasers, and the rotating room.
Observation of Rayleigh scattering and airglow
Authors: Aridgides Athanasios , Pinnock Ralph N. , Collins Donald F.
Published: March 2005

A steerable 0.25-m Ebert monochromator and photomultiplier detector were employed to measure the spectra of the clear daytime sky (Rayleigh scattering). The day sky intensity as a function of wavelength was observed to vary as λ−4 in agreement with Rayleigh’s predictions and observations. The same monochromator and detector with the addition of a multichannel scaler were used to observe the night sky spectra (airglow). The oxygen (OI) emission at 557.7 nm was observed from the ground by using this technique.
Connection between the dispersion relation, surfaces of constant energy, and energy bands in solids
Authors: Dalven Richard
Published: March 2005

The aim of this paper is to exhibit the relationship, for free electrons in two dimensions, between the dispersion relation ε=ε (k) = (h/2/2m)(kx2+ky2), the contours of constant energy, and energy band structures in various directions. It has been found that these results, while well known, are not usually interconnected and presented together for the student.
Refractive indices of gases at microwave frequencies
Authors: Goodhead D. T. , Wantenaar G. H. J. , Bacon M. E.
Published: March 2005

A simple microwave interferometer capable of measuring small phase shifts is described. The interferometer can easily be incorporated in an undergraduate laboratory. The interferometer is used to determine the relative refractive indices of gases to within a few parts per million. Analysis of the reflection in the test chamber can provide an interesting extension to the usual treatment of multiple reflections.
Teaching a physics-and-society course
Authors: Schroeer Dietrich , Spencer Charles
Published: March 2005

The goals, teaching methods, and requirements of a six-year-old physics-and-society course are presented and related to the course’s content and survey approach. The problems, frustrations, and rewards experienced in developing and teaching the course are shared.
Obtaining a Heisenberg Hamiltonian from the Hubbard model
Authors: Cleveland Charles L. , Medina A. Rodrigo
Published: March 2005

A pedagogically useful method of obtaining a Heisenberg spin–spin interaction from a familiar many-electron Hamiltonian by means of ordinary degenerate perturbation theory is presented.
Exposure corrections for macrophotography
Authors: Nikolic N. M.
Published: March 2005

A method for determining the exposure correction factors in close-up photography and macrophotography is proposed. It eliminates all the calculations during picture-taking sessions, and it allows one to use the light meter calculator in the usual manner to obtain the proper f-stop–exposure time combinations appropriate to the level of object illumination. The method was tested up to 6.5× magnification and found to give perfectly exposed negatives and slides.
Spectral density in time-dependent perturbation theory
Authors: Lagendijk Ad
Published: March 2005

The spectral density of radiation is defined within the context of the random phase approximation. This gives an expression for the radiation density in terms of the Fourier components of the field amplitudes. The result is applied to the case of a molecule in interaction with light. The approach with Fourier integrals overcomes some difficulties associated with an approach which uses a summation of discrete waves.
The beginning of quantum statistics: A translation of ’’Planck’s law and the light quantum hypothesis’’
Authors: Bose [Satyendranath] , Theimer O. , Ram Budh
Published: March 2005

The phase space of a light quantum in a given volume is subdivided into ’’cells’’ of magnitude h3. The number of possible distributions of the light quanta of a macroscopically defined radiation over these cells gives the entropy and with it all thermodynamic properties of the radiation.
Elementary view of fusion implosions
Authors: Osborn R. K. , Mayer F. J.
Published: March 2005

The implications of some elementary solutions of the hydrodynamic equations for simple fluids are explored for scaling relations for—and insight into—the dynamics of imploded fusion targets. Because the model is so simple, analytical solutions are available and explicit formulas for such quantities as neutron yield, bremsstrahlung spectra and yield, etc., can be deduced. Where possible, comparison is made with the results of laser-fusion experiments being performed in the KMS Fusion laboratories.
Noether’s theorem in classical mechanics
Authors: Desloge Edward A. , Karch Robert I.
Published: March 2005

A simple statement of Noether’s theorem as it applies to classical mechanics is given and proved. It is then used to generate constants of the motion associated with Lagrangians possessing certain transformation properties.
Large-amplitude pendulum experiment: Another approach
Authors: Hall Donald E. , Shea Michael J.
Published: March 2005

A pendulum may swing at amplitudes greater than 90° if the bob is suspended on a solid rod instead of a string. In this way the increase in period T with amplitude α can be made much more obvious. We describe a student experiment which uses angles up to 160° or more and determines several terms in the Taylor series for T (α). We recommend an emphasis on graphical analysis for empirical determination of parameters, rather than merely checking data against a ’’known’’ theoretical curve.
A physical explanation of the gyroscope effect
Authors: Edwards P. L.
Published: March 2005

A force applied perpendicular to a point on the axis of a rotating gyroscope does not cause the point of application, unless it happens to be the center of gravity, to move in the direction of the force, as might be expected, but at approximately 90° to it. We show that this effect can be understood physically by considering the rotation of two equal masses mounted on a frame of negligible mass. It is also noted that the mathematical simplifications made in the study of rigid-body motion often tend to obscure what is happening physically.
Some plasma physics experiments on electrical conductivity and similarity laws
Authors: Pytlinski J. T. , Alexeff I.
Published: March 2005

Two elementary experiments treating plasma electrical conductivity and similarity laws are described. Plasma is generated by means of commercially available gas tubes. Basic electronic equipment of low cost, available in most laboratories, is used. The experiments are especially suitable for an introductory course in plasma physics.
A validity study of the multiple-choice component of the advanced placement physics C examination
Authors: Pfeiffenberger G. Will , Modu Christopher C.
Published: March 2005

In 1974–1975, the multiple-choice sections of both parts of an Advanced Placement (AP) Physics C Examination were given as parts of final examinations to college students completing the appropriate semester of an introductory calculus-based physics course. Almost 3800 candidates were tested in 15 highly selective colleges. The college students scored on the average about the same as or slightly lower than the AP candidates who also took the same exams and the scores of the college students correlated quite well both with end-of-course grades and with rankings of the students’ physics achievement made independently by their instructors. The equivalences between AP and college grades were estimated; both for mechanics and for electricity and magnetism, an AP grade of 4 or 5 was roughly equivalent to a college A, and AP 3 to a college B, and an AP 2 to a college C.
Centrifugal buoyancy forces
Authors: Wick Gerald L. , Tooby Paul F.
Published: March 2005

The buoyancy force on a particle in a rotating fluid is derived. We have not seen a derivation of this type of buoyancy force elsewhere although it is often presented de facto. The buoyancy force in hydrostatics is also rarely derived except for rectangular shapes. We derive it for a sphere.
Polarization of a polar gas by external and internal electric fields
Authors: Parker G. W.
Published: March 2005

Linear-polar molecules in an external field contribute to two kinds of polarization effects which may be described in classical terms. First, the external field E produces a torque on each molecule which tends to align its electric dipole moment μ in the direction of the field. At high temperatures the average alignment energy is 〈μ⋅E〉=−μ2E2/3kT. Second, each molecule experiences an internal electric field due to nearby molecules which tends to align the dipole moment of a molecule along the internal field it experiences. This results in an average attractive interpair potential energy 〈U〉=−2μ4/3r6kT. A method of estimating 〈U〉 is described, which is based on the division of molecules into two classes, ’’slow’’ or ’’fast’’, according to their rotational speed. This approach can also be used to estimate 〈μ⋅E〉. Results for a three-dimensional gas are contrasted with those for a two-dimensional gas, and the approach to equilibrium of 〈μ⋅E〉 for a two-dimensional gas is described in detail.
Polarization characteristics of scattered light
Authors: Shaw D. E. , Wunderlich F. J. , Hones M. J.
Published: March 2005

An undergraduate experiment investigating the polarization characteristics of light scattered from a dielectric cylinder is presented. Students generally find the results surprising; however, the observations support the predictions of classical electromagnetic theory.
Forced harmonic oscillator in the interaction picture
Authors: Ferrell Richard A.
Published: March 2005

The interaction picture of quantum mechanics is used to calculate the unitary time development operator for a harmonic oscillator subject to an arbitrary time-dependent force. The result is identical to that obtained from the more usual method of the Heisenberg equations of motion, except for a phase factor which the Heisenberg picture method is unable to determine. A simplified derivation of the phase factor is given in the adiabatic limit, as well as a discussion of some possible physical effects which would depend upon the phase factor.
Nonlinear vector product to describe rotations
Authors: Aharonov Yakir , Farach Horacio A. , Poole Charles P.
Published: March 2005

A method is developed for treating successive rotations in terms of nonlinear products of rotation vectors. Combinations of ordinary scalar and vector products yield the same results that may be more commonly arrived at by the use of quaternions or 2×2 unitary matrices. The method automatically provides the direction of the axis and the value of the rotation angle of the single rotation that is equivalent to the product of two or more successive rotations. This information is not readily obtained from the usual matrix rotation method of solving the successive rotation problem. The method is applied to the case of a rotation about the [1 1 1] direction, successive π rotations about orthogonal axes, and the treatment of continuous rotations.
Time-dependent scattering of wave packets in one dimension
Authors: Hammer C. L. , Weber T. A. , Zidell V. S.
Published: March 2005

This paper treats the scattering of wave packets in one space dimension at the mathematical level of the first-year graduate student. The analytic properties of the general-scattering solutions are emphasized, thereby making the analysis useful as introductory material for a more sophisticated S-matrix treatment. Resonant scattering, time delay, and line shape, as well as the relationship between bound and resonant states, all follow as a natural consequence of the analysis.
Physics and the art of kicking and punching
Authors: Blum Haywood
Published: March 2005

A consistent description and analysis of a martial arts demonstration is presented. The physics associated with striking and breaking a bone or a board is developed from an energy point of view.
The gyroscope: An elementary discussion of a child’s toy
Authors: Case William
Published: March 2005

An elementary discussion of the gyroscope is presented. It is based on convservation of angular momentum and energy and does not require calculus. The results are identical with those obtained with the usual Lagrangian–Euler angle treatment. The motion is then analyzed graphically, and conditions under which the top falls are considered.
Teaching megalithic astronomy
Authors: Manning Robert
Published: March 2005

Observational astronomy was carried out in detail by members of the cultures which flourished in western Europe in the third and second millennia b.c. Understanding the methods and goals of these observers necessitates consideration of the Sun and Moon and their motions in some detail. The methods by which eclipses may be predicted is also examined. Finally, the case to be made for Stonehenge as an observatory is reconsidered.
One-dimensional collisions and Chebyshev polynomials
Authors: Towne Dudley H. , Hadlock Charles R.
Published: March 2005

This paper investigates a sequence of inelastic collisions resulting among three spheres, whose centers are on a line, when at the outset the leftmost sphere is propelled to the right and the other two spheres are at rest. Explicit expressions are obtained for velocity, time, and distance variables, and a simple method is given for determining the total number of collisions which take place. Under certain circumstances this number is infinite; in this case the final state is shown to be achieved in finite time and to be essentially the same as for the completely inelastic case. The Chebyshev polynomials of the second kind are prominent in the analysis. The results are applied to generalize work of R. H. Romer concerning the motion of air-carts on a track.
Mean field theory, the Ginzburg criterion, and marginal dimensionality of phase transitions
Authors: Als-Nielsen J. , Birgeneau R. J.
Published: March 2005

By applying a real space version of the Ginzburg criterion, the role of fluctuations and thence the self-consistency of mean field theory are assessed in a simple fashion for a variety of phase transitions. It is shown that in using this approach the concept of ’’marginal dimensionality’’ emerges in a natural way. For example, it is shown that for many homogeneous structural transformations the marginal dimensionality is two, so that mean field theory will be valid for real three-dimensional systems. It is suggested that this simple self-consistent approach to Landau theory should be incorporated in the teaching of elementary phase transition phenomena.
Matter, energy and life—physics in an interdisciplinary general education science course
Authors: Sokoloff David R. , Holloway Walter M.
Published: March 2005

For the past six years, freshman nonscience students at The University of Michigan–Dearborn have been introduced to the sciences through a unique, one-year, integrated, interdisciplinary, team-taught course, ’’Matter, Energy and Life.’’ The principal objective of the course is to develop the scientific literacy of the students and to prepare them to deal with the scientific problems they will face as citizens. Physics principles represent an essential component of the course, and are integrated into both lectures and laboratory exercises. Experience with this approach, and both peer and student evaluations, have shown its effectiveness in generating student interest in the sciences.
The laboratory spring–mass oscillator: an example of parametric instability
Authors: Cayton Thomas E.
Published: March 2005

The peculiar tendency of the laboratory spring–mass oscillator to swing sideways is analyzed. The physical explanation for this motion involves a decay mode called a ’’parametric instability’’; the ’’inverse parametric instability’’ is also intimately involved. The theory of a completely reversible cyclic process is developed and a method of predicting the maximum swinging amplitude is presented. This inherently nonlinear phenomenon illustrates the important role played by instabilities in transferring energy from one degree of freedom of a system to another. An analogy is drawn between the swinging of the oscillator and the interaction among several waves propagating in a nonlinear medium.
Beyond the Kepler problem—an action-angle example
Authors: Scanio Joseph J. G.
Published: March 2005

The motion of a particle in a noncentral potential is discussed using the action-angle formalism. The results are verified in the small oscillation approximation.
Simulating actual research conditions as a means of enhancing the value of advanced student laboratories
Authors: Buckwald R. A.
Published: March 2005

A novel method of teaching advanced physics laboratories has been developed. The method simulates research conditions by creating a student-written literature and requiring students to make researchlike decisions.
’’The Age of Newton’’ workshops
Authors: Calvert J. B. , Tuttle E. R. , Martin Michael S. , Warren Peter
Published: March 2005

The optics, mechanics, and mathematics workshops for ’’The Age of Newton’’ are described in detail. These workshops can be used separately and are of particular interest to an institution developing a curriculum in the history of science, or a new approach to the education of nonscience students, as they involve extensive laboratory experience as well as the customary readings. Although the core of the material covered is Newtonian, use is made of appropriate modern concepts and equipment.
An intuitive approach to group representation theory
Authors: Wolbarst A. B.
Published: March 2005

The purpose of this article is to outline a nonrigorous and highly intuitive introductory approach to the sort of group representation theory used in molecular and solid state physics. We examine the real three-space spanned by orthonormal polar basis vectors {‖i〉, i=1,2,3}; first it is shown that the familiar block diagonal ’’rotation matrix’’ is simply the {‖i〉} representation of the geometric transformation operator ?φ which causes a counterclockwise rotation of any three-space polar vector by the angle φ about the ‖3〉 axis. By applying this argument to the group of symmetry operators of the ammonia molecule, it becomes self-evident that the two irreducible representations obtainable from the {‖i〉} representation of C3v correspond to subspaces of real-space invariant relative to the six operators of that group. And the basis vectors which span these invariant subspaces (and which produce the corresponding irreducible representations) have clearly defined symmetry (A1 and E) properties under the operations of C3v. This idea is further illustrated in consideration of the representation produced by the in-plane normal modes of vibration of the three hydrogen atoms in ammonia. Finally, it is shown that the approach can readily be extended into function space.
Scores on a Piaget-type questionnaire versus semester grades for lower-division college physics students
Authors: Barnes George
Published: March 2005

A study involving 338 students in six different lower-division physics courses is reported in which students’ Piagetian levels of intellectual development as determined by a written questionnaire versus final semester grades are compared. A good correlation would provide the instructor with a useful counseling tool while a poor or zero correlation would not. In either case, the questionnaire results can guide the selection of instructional materials and techniques for the class. The correlation coefficients were found to be positive, but low, for the grades A, B, and C, and the statistical scatter diagrams show a wide spread of Piagetian levels of intellectual development within each letter grade level. Other factors than the ability to think logically appear to be of greater importance for the D group, and no correlation can be seen for the W’s and F’s. The wide spread of Piagetian levels of thought for each grade level suggests that students can somehow attain passing, if not high, grades in the more elementary of these courses even though they appear to lack the ability to think formally, at least at the beginning of the course. Logical thought appears to be a more necessary attribute as students progress through the engineering physics sequence, however.
Geometric model for holography
Authors: Jeong Tung H.
Published: March 2005

A geometric model is developed to interpret the physical meaning of various major characteristics of ’’real’’ holograms. Without invoking highly mathematical principles, but, at the same time, without sacrificing basic physics, the model allows the development of an intuitive understanding of the following characteristics: the virtual image, the real image, redundancy, multiple scenes, white light or Lippmann–Bragg reflection holograms; and then leads into the explanation of the hypothetical ’’thin’’ hologram.
Elemental derivation of the Babinet principle in electromagnetic form
Authors: Andrews C. L. , Margolis D. P.
Published: March 2005

Two complementary, thin screens treated in the Babinet principle have one thing in common, the line of their edges. Employing the assumption that scattering of electromagnetic waves from a thin, conducting screen is solely from the elements of the edges, we have made a simple derivation of the Babinet principle in electromagnetic form. We needed to treat but one element of edge with the aperture and conductor interchanged. The factors which affect the amplitudes and phases of the electric and magnetic scattered wavelets reaching any point of observation from the common element of edge of the complementary screens are identical except for phase factors of 0° or 180° caused by polarization effects at the conducting edge. Symmetry conditions from electromagnetic theory yield those factors. We have illustrated the Babinet principle in electromagnetic form by tabularly expressing the scattered waves from two complementary half-planes. These results also were based on the assumption that scattering by a thin screen is solely from the edges.
Optical-model and coupled-channels calculations in quantum-mechanical scattering
Authors: Doyle Samuel D. , Eck John S. , Thompson W. J. , Weaver O. L.
Published: March 2005

Non-Hermitian Hamiltonians are used in many research areas as approximate models of physical systems, for example, the optical-model potential in nuclear physics. Such Hamiltonians are rarely treated in introductory quantum mechanics. Here the quantum scattering problem of a two-state system is treated exactly for the case of one-dimensional square-well potentials. By introducing an appropriate optical-model potential, an approximate solution for one of the two states is obtained. The exact and approximate solutions are compared for a realistic example.
Torus topology of the static current loop field
Authors: Fenster Stanley
Published: March 2005

The filamentary current loop of magnetostatics is naturally associated with toroidal topology rather than the usual cylindrical or spherical topology. The field near the wire is best explored in toroidal coordinates, but even the far magnetic dipole field may be found this way. The loop field becomes infinite near the wire just as does the endless straight wire field, but another, not well-known logarithmic infinity occurs that is proportional to the curvature. We demonstrate these facts and, in addition, mention a certain duality with the electric field of a ring of charge.
Experiments using a tunnel diode oscillator
Authors: Fox John N. , Trefny John U.
Published: March 2005

A description is given of an apparatus suitable for measuring magnetic susceptibility in the undergraduate laboratory. Several applications are considered in detail, and extension of the technique to nonmagnetic studies is briefly discussed.
The conservation principles and Kepler’s laws of planetary motion
Authors: Motz Lloyd
Published: March 2005

Kepler’s three laws of planetary motion are derived algebraically from conservation principles without introducing Newton’s law of force explicitly. This procedure can be presented to students who have had no more than high school algebra.
Velocity space and the geometry of planetary orbits
Authors: Abelson Harold , diSessa Andrea , Rudolph Lee
Published: March 2005

We develop a theory of orbits for the inverse-square central force law that differs considerably from the usual deductive approach. In particular, we make no explicit use of calculus. By beginning with qualitative aspects of solutions, we are led to a number of geometrically realizable physical invariants of the orbits. Consequently, most of our theorems rely only on simple geometrical relationships. Despite its simplicity, our planetary geometry is powerful enough to treat a wide range of perturbations with relative ease. Furthermore, without introducing any more machinery, we obtain full quantitative results. The paper concludes with suggestions for further research into the geometry of planetary orbits.
Term projects on interstellar comets
Authors: Mack John E.
Published: March 2005

Two calculations are presented of the probability of detection of an interstellar comet, under the hypothesis that such comets would escape from comet clouds similar to that believed to surround the sun. The results are that an encounter might have happened within historical times, although the simple assumptions used render the calculation uncertain to about a factor of 10. Three problems are proposed, each of which would be a reasonable term project for a motivated undergraduate and the answers to which would be of interest and are not presently known.
Computational method for electrical potential and other field problems
Authors: Hastings David A.
Published: March 2005

The finite differences relaxation method is proposed as a teaching tool in secondary school and university level courses discussing electrical potential, temperature distribution in a region, and similar subjects. This paper outlines the theory and operating procedures of the method, and discusses examples of teaching applications. Some examples of physical modeling methods are included for comparison and as possible laboratory experiments.
A variational Hartree-type calculation
Authors: Robiscoe R. T.
Published: March 2005

The ground state of the two-electron atom is treated by a calculation, suggested by Slater, which combines features of both the variational method and Hartree’s method of self-consistent fields (SCF). The calculation is mathematically simple, and it exposes the basic physics of the SCF method in a clear and direct way. The result for the first ionization potential for the two-electron atom is in good agreement with experimental values for atomic number Z?2.
Elementary introduction to the Green’s function
Authors: Whitten R. C. , McCormick P. T.
Published: March 2005

A technique, using the method of variation of parameters for solving differential equations, is developed for introducing Green’s functions early in an undergraduate curriculum. Various examples are presented.
Laboratory exercise on the inverse square law
Authors: Kruglak Haym
Published: March 2005

Students investigate in the introductory laboratory the relationship between distance from a light source and illuminance. A graphical display and analysis of data leads to the ’’discovery’’ of the inverse square law. Its validity is confirmed by excellent agreement between predicted and observed values. A 12-V high-intensity bulb is used as a point source; the detector is an inexpensive silicon photocell connected to a milliammeter. The assumption of a point source requirement is tested by the use of a diffusing screen.
National influence and evaluation of college physics courses—Is there any?
Authors: Layman John W.
Published: March 2005

A survey is made of 24 years of this Journal’s seeking evidence of physics courses with national stature, courses with extensive evaluation, and evidence of national, regional, or multi-institutional study of college physics teaching. During this period there were 85 course or laboratory reports, but the majority (59) occurred in the last four years. Few contained extensive evaluation reports, only two achieved national stature, and the outlook for large-scale study and evaluation of physics programs looks bleak. There may be cause for optimism, however, in the editorial policy change for the American Journal of Physics discussed in the September 1973 issue. Evidence that a change may already be occurring is offered in this article.
Thermodynamics of a simple rubber-band heat engine
Authors: Mullen J. G. , Look George W. , Konkel John
Published: March 2005

We analyze the thermodynamics of a simple heat engine. The engine’s efficiency is calculated for an idealized but reasonable model. The engine’s work cycle is compared with a Carnot cycle, and it is shown to be equivalent to the Carnot cycle as an extremely ideal limiting case. A working model of the engine is easily constructed for classroom demonstrations. We measured the force law parameters for a working model, and we estimate the efficiency of this model. The estimated efficiency of our demonstration engine is small compared with that of a Carnot engine operating at the same temperatures. We show that a Carnot engine could in principle be constructed based on the thermal expansion concept, but its efficiency would be intrinsically small when rubber is the working substance because of the inherently small incremental temperature increase possible in an adiabatic expansion.
Does a gravitational red shift necessarily imply space-time curvature?
Authors: Marsh G. E. , Nissim-Sabat C.
Published: March 2005

Schild’ has proposed a heuristic agrument which attempts, to show that any gravitational red shift requires that the geometry of space−time be curved. It is our intention to show that this argument is fallacious and we believe that no argument which attempts to infer space−time curvature solely from the gravitational red shift can be valid.
My recollections of Wolfgang Pauli
Authors: Jordan Pascual , Freeman Translated from the German by Ira M.
Published: March 2005

Editor’s note: From time to time this journal publishes translationsa of articles previously unavailable in English. Professor Ira Freeman of Rutger’s University has furnished us with this translation and Professor Pascual Jordan has kindly consented to our publication of it.
Report on the Conference on Tradition and Change in Physics Graduate Education
Authors: Green Alex E.S.
Published: March 2005

We report the major thrust of the Conference on Tradition and Change in Physics Graduate Education, held at Pennsylvania State University on 19−23 August 1974. %Most of the dialogue dealt with the employment problems of the physics community, particularly of its younger members, and with measures which might be taken at the graduate school level to alleviate these problems. %These measures involve a serious reexamination of our traditions and a deliberate set of innovations and diversifications to maintain physics as a viable career option.
Undergraduate laboratory investigation of the dielectric constant of ice
Authors: Gingle A. , Knasel T. M.
Published: March 2005

An experiment is described for a college level electricity and magnetism laboratory course that enables the measurement of the real and imaginary part of the dielectric constant of ice as a function of frequency.
A look at some rising bubbles
Authors: Vermillion Robert E.
Published: March 2005

A small air bubble in a liquid is observed as it slowly rises toward the surface under conditions such that the change in hydrostatic pressure with depth cannot be neglected. The equation of motion is found to be of the form predicted by a simple, laminar−flow model. Bubbles which rise faster move with a distinct oscillatory motion for which there is no simple explanation.
Calculation of a bound state wavefunction using free state wavefunctions only
Authors: Brownstein K. R.
Published: March 2005

A pedagogical example is presented in which the completeness of the free state wavefunctions of a Hamiltonian can be explicitly checked. For certain values of the potential strength the free states prove to be complete. For other values of the potential strength the free states are shown to be incomplete and the extent of this incompleteness is shown to consist of precisely one function. Using the fact that the totality of all energy eigenfunctions must be complete, this single bound state wavefunction is calculated using the free state wavefunctions only.
Negative temperatures and negative dissipation
Authors: Machlup Stefan
Published: March 2005

Negative absolute temperature, defined in terms of the Boltzmann factor, corresponds to an upside-down energy pyramid. The example of the laser shows population inversion to be accompanied by the switch from absorption to emission, that is, from positive to negative dissipation, from increasing disorder throughout a system to increasing order in a subsystem. Early treatments of the negative-temperature concept are by Onsager and by Ramsey. Ramsey’s ’’essential requirements’’ are shown to be too strong. A TS diagram for a Carnot cycle operating between two negative temperatures clarifies the origin of amplification. Some biological negative-resistance amplifiers (nerve, muscle), in particular those involving ordered arrays of water molecules, are conjectured to have negative-temperature subsystems.
Temperature effects on the musical pitch of a stretched string
Authors: Kelly Robert E.
Published: March 2005

The effect of temperature changes on the pitch of a stretched string of constant length is presented for both the flexible and stiff string. It is shown that the main contribution is through a tension change, but temperature variations of Young’s modulus, coefficient of linear expansion, and radius also produce secondary effects. Numerical examples are presented for a steel wire in a piano. A relaxation of constant length is treated for the flexible string, and the relative importance of the temperature-dependent parameters is discussed, including an entropy analysis.
Electronic falling body simulator
Authors: Goodman John M.
Published: March 2005

An analog electronic simulator for the motion of an object projected horizontally in a vertical acceleration field is described. The device features include adjustable values for both the horizontal speed and the strength of ’’gravity.’’ A metronome circuit gives aural and graphic time information. The trajectories are displayed on a storage oscilloscope. Photographs of typical families of curves are shown. [The apparatus described in this article was first prize winner in the College Demonstration category of the 1975 AAPT Apparatus Competition—Editor]
Karate strikes
Authors: Walker Jearl D.
Published: March 2005

Analysis of a forward karate punch is made as an example of collision mechanics. The energy lost to deformation of an opponent is evaluated, and the deformation is shown to be maximized if contact is made when the fist has the greatest speed. In karate fighting the maximum deformation is obtained by focusing a punch to terminate several centimeters inside an opponent’s body. The average impact force is calculated and compared with that neeeded to break a human bone by stressing it beyond its ultimate bending stress value. Similar breaking forces needed for bricks and wooden boards are also computed. A brief description of breaking demonstrations for the physics classroom is made.
Simple approach to the multiphoton states of a thermal radiation field
Authors: Afsenius Sven-Åke
Published: March 2005

The multiphoton states of a thermal radiation field are studied by using elementary methods. The distribution of states and the degeneracy parameter are discussed.
Determination of m, e/m, and M
p/m by the study of the isotope structure in hydrogen
Authors: George S.
Published: March 2005

Using a commercially available hydrogen–deuterium light source and a 3.4-m Ebert plane grating spectrograph, the wavelengths of the first six pairs of the Balmer series are obtained. From the results, first, the series limit, Rydberg constant, and ionization potential of hydrogen are found from the graph. Then, by means of formulas involving wave numbers of hydrogen and deuterium and by knowing the Faraday constant, the values of m, e/m, and Mp/m are determined. All the values are found to be in good agreement with accepted values. From the results, this experiment is recommended for an upper division optics and spectroscopy or quantum physics laboratory.
The Kerr effect in nitrobenzene—a student experiment
Authors: Knudsen Arthur W.
Published: March 2005

In any method for quantitatively determining the Kerr constant of nitrobenzene, the question of the purity of the material cannot be ignored. In the method described, account is explicitly taken of the effect of impurity ions in the dielectric on the optical performance of the Kerr cell. Thus, although nitrobenzene of less than the highest attainable purity is employed, results comparable in accuracy to expert determinations of the Kerr constant are obtained. The method, therefore, offers possibilities for a student experiment. Details of cell construction, nitrobenzene purification, optical procedures, and data reduction are given. Also included is a general discussion of electrical effects and the electro-optical effects in Kerr cells having dielectrics that are less-than-perfect electrical insulators.
Interdisciplinary program at a small college
Authors: Ferrell T. L.
Published: March 2005

A time-tested program of interdisciplinary service courses at a small college is described. The program involves faculty from areas other than physics and has stabilized over a period of seven years at an academically successful level. Drawbacks as well as advantages of the program are described.
Brachistochrone with Coulomb friction
Authors: Ashby N. , Brittin W. E. , Love W. F. , Wyss W.
Published: March 2005

The problem of finding the curve of most rapid descent of a bead sliding along a wire, from one fixed point to another, under the simultaneous influence of gravity and friction, is solved. A remarkable feature of the problem is that the solution can be expressed in closed form, in terms of elementary functions.
A world of Bose particles
Authors: Sudarshan E. C. G.
Published: March 2005

Editor’s Note: Satyendranath Bose, known primarily as one of the co−founders of quantum statistics, died on 4 February 1974, a few weeks after a symposium in honor of his 80th birthday was held at the Saha Institute for Nuclear Physics in Calcutta. The following paper, originally prepared in that connection, reviews some of the more important developments in particle physics which followed from the fundamental insight contained in a four−page paper published by Bose exactly fifty years ago. At the request of the editors of the AJP, Professor Sudarshan has kindly consented to adapt his paper for reproduction here. We would like to thank William Blanpied for bringing this paper to our attention.
A Serpentinite-Hosted Ecosystem: The Lost City Hydrothermal Field
Authors: Kelley Deborah S. , Karson Jeffrey A. , Früh-Green Gretchen L. , Yoerger Dana R. , Shank Timothy M. , Butterfield David A. , Hayes John M. , Schrenk Matthew O. , Olson Eric J. , Proskurowski Giora , Jakuba Mike , Bradley Al , Larson Ben , Ludwig Kristin , Glickson Deborah , Buckman Kate , Bradley Alexander S. , Brazelton William J. , Roe Kevin , Elend Mitch J. , Delacour Adélie , Bernasconi Stefano M. , Lilley Marvin D. , Baross John A. , Summons Roger E. , Sylva Sean P.
Published: March 2005

The serpentinite-hosted Lost City hydrothermal field is a remarkable submarine ecosystem in which geological, chemical, and biological processes are intimately interlinked. Reactions between seawater and upper mantle peridotite produce methane- and hydrogen-rich fluids, with temperatures ranging from <40° to 90°C at pH 9 to 11, and carbonate chimneys 30 to 60 meters tall. A low diversity of microorganisms related to methane-cycling Archaea thrive in the warm porous interiors of the edifices. Macrofaunal communities show a degree of species diversity at least as high as that of black smoker vent sites along the Mid-Atlantic Ridge, but they lack the high biomasses of chemosynthetic organisms that are typical of volcanically driven systems.
The Brain of LB1,
Homo floresiensis
Authors: Falk Dean , Hildebolt Charles , Smith Kirk , Morwood M. J. , Sutikna Thomas , Brown Peter , Jatmiko  , Saptomo E. Wayhu , Brunsden Barry , Prior Fred
Published: March 2005

The brain of
Homo floresiensis
was assessed by comparing a virtual endocast from the type specimen (LB1) with endocasts from great apes,
Homo erectus, Homo sapiens
, a human pygmy, a human microcephalic, specimen number Sts 5 (
Australopithecus africanus
), and specimen number WT 17000 (
Paranthropus aethiopicus
). Morphometric, allometric, and shape data indicate that LB1 is not a microcephalic or pygmy. LB1's brain/body size ratio scales like that of an australopithecine, but its endocast shape resembles that of
Homo erectus
. LB1 has derived frontal and temporal lobes and a lunate sulcus in a derived position, which are consistent with capabilities for higher cognitive processing.