bluuebunny/crossref_metadata_2025 huggingface dataset:
What Ampère could have done: A simple demonstration of the Biot–Savart and magnetic force laws
Authors: Peach Milton O. , Shirely Leland K.
Published: March 2005

Within six years of the time Ampère learned of Oersted’s observations, he had completely elucidated the principles by which the magnetic interactions between steady currents can be calculated. In constructing his demostration, he used Oersted’s experiment only to infer that, in general, two electrical circuits will exert forces on each other; and he made no use of previous knowledge of magnetics. Eschewing such restrictions, we give a simpler demonstration of a simpler but equivalent result. Our method is one that Ampère could have chosen, and that (unlike his) can be understood by any junior–senior student in physics or engineering.
Electromagnetic momentum introduced simply
Authors: Casserberg B. R.
Published: March 2005

It is shown in a very simple manner how a momentum density may be associated with an electromagnetic field.
Backscattering of light from a water droplet: The glory effect
Authors: Gillis P. , Deleuze C. , Henri V. P. , Lesceux J. M.
Published: March 2005

We discuss the theoretical attempts at explaining the glory effect and describe a simple setup that permits visualization of the glory ray.
Site-by-site Madelung energies in semi-infinitive NaCl
Authors: Schwalm William A.
Published: March 2005

Superposition can be used to determine electrostatic energies of ions at arbitrary sites on a semi-infinite NaCl lattice. In this way, Madelung energies are found for ions at locations near a surface, an edge, or a corner of a macroscopic crystal. Proceeding sequentially into the crystal from a site on a surface or an edge, the electrostatic energies tend rapidly to the bulk value. Sequences of ions originating at a corner, however, have energies that approach a limiting value only slowly. The method is a rather direct application of Coulomb’s law that should be understandable to interested students in elementary physics courses. It provides an extraordinary exercise in the use of superposition.
Undergraduate laboratory experiment to measure the threshold of vision
Authors: White H. W. , Chumbley P. E. , Berney R. L. , Barredo V. H.
Published: March 2005

A laboratory experiment to measure the threshold of vision is described. The exercise was done by students in the second-semester college physics course. The students measured their threshold of vision using a simple apparatus.
Measurement and analysis of large-angle pendulum motion
Authors: Zilio S. C.
Published: March 2005

A pedagogical experiment to study the frequency spectral composition of the pendulum motion as a function of its amplitude is described. The angle is measured with a very simple apparatus, whose major components are an x–y recorder and a one-turn helipot. In order to obtain the frequency spectrum, a pocket calculator is used to Fourier transform the data by means of the discrete Simpson’s approximation. The period is determined directly from the angle versus time plot with an accuracy of a few parts in 103.
One-dimensional hydrogen molecule revisited
Authors: Lapidus I. Richard
Published: March 2005

The energy of the one-dimensional hydrogen molecule with δ-function interactions between the particles is obtained using exact hydrogen molecule ion wave functions, a symmetrized product of hydrogen atomic wave functions and a linear combination of hydrogen atomic orbital wave functions. A variational calculation is carried out for each of the three cases to obtain wave functions that yield lower total molecular electronic energies.
Properly used ’’aliasing’’ can give better resolution from fewer points in Fourier transform spectroscopy
Authors: D’Astous Y. , Blanchard M.
Published: March 2005

In the past years, the Journal has published a number of articles1–5 devoted to the introduction of Fourier transform spectroscopy in the undergraduate labs. In most papers, the proposed experimental setup consists of a Michelson interferometer, a light source, a light detector, and a chart recorder. The student uses this setup to record an interferogram which is then Fourier transformed to obtain the spectrogram of the light source. Although attempts have been made to ease the task of performing the required Fourier transform,6 the use of computers and Cooley–Tukey’s fast Fourier transform (FFT) algorithm7 is by far the simplest method to use. However, to be able to use FFT, one has to get a number of samples of the interferogram, a tedious job which should be kept to a minimum. (AIP)
Skyhook: Another space construction project
Authors: Ebisch Konrad E.
Published: March 2005

The ’’skyhook’’ concept is suggested as an ideal ’’real-world’’ problem for physics students. (AIP)
Two theorems in classical mechanics
Authors: Sharan Pankaj
Published: March 2005

Two simple results are proved for a set of physical quantities that are the classical analog of the ‘‘complete set of commuting observables.’’
Strange bound states in the Schrödinger wave equation: When usual tunneling does not occur
Authors: Meyer-Vernet N.
Published: March 2005

In most textbooks on quantum mechanics, it is asserted that the bound states of a localized potential have negative energies. To stress that this view should be taken with caution, we give several examples of scalar potentials that tend to zero at infinite distance and yet possess one or several discrete positive bound states for the Schrödinger single-particle wave equation. The consequence that usual tunneling may not occur, though it should according to a superficial view, is of interesting pedagogical value.
Physical properties of de Broglie’s phase waves
Authors: Espinosa James M.
Published: March 2005

An account of de Broglie’s introduction of phase waves is given that emphasizes that they are a relativistic concept. The properties of the frequency, wavelength, and velocity of de Broglie waves are found under a Lorentz transformation. A nonrelativistic specialization of phase waves is obtained, and the appropriate frequency, wavelength, and velocity are defined. The transformation properties of these parameters under a Galilean transformation are given. The concept of a group velocity for phase waves is re-examined and shown to be applicable.
Connection between nonlinear resonance and statistical behavior
Authors: Crawford John David , Lott John , Riecke Hermann
Published: March 2005

We present an introductory discussion of nonlinear Hamiltonian dynamics and ergodic theory. The phenomenon of nonlinear resonance is described, and we explain its significance for dynamics and statistical physics. Finally, a simple and important illustrative model is presented.
A method for numerical determination of eigenvalues
Authors: Denham S. A. , Harms B. C. , Jones S. T.
Published: March 2005

We present a novel method of obtaining the energy eigenvalue spectrum for a Hamiltonian whose interaction term is a polynomial in one independent variable. The method is simple in concept and can be easily implemented on a minicomputer with a Basic compiler. The method extends the range of potentials for which the energy spectra is easily obtained and is therefore of value to students in introductory quantum mechanics. To show the utility of the method we use it to obtain the energy spectra for the anharmonic oscillator and for a non-Hermitian Hamiltonian.
General relativity primer
Authors: Price Richard H.
Published: March 2005

In this tutorial article the physical ideas underlying general relativity theory are discussed and the basic mathematical techniques (tensor calculus, Riemann curvature) needed to describe them are developed. The general relativity field equations are presented and are used in several applications including a discussion of black holes.
Note on the Lamb shift
Authors: Davies B.
Published: March 2005

The relationship between ‘‘old-fashioned’’ and covariant perturbation theory for the Lamb shift is elucidated, leading to some clarification of various points in the standard treatments. The results are applied to a brief examination of explanations that invoke semiclassical methods and zero-point fluctuations.
Nonlinear effects in a simple mechanical system
Authors: Arnold Thomas W. , Case William
Published: March 2005

We describe a nonlinear mechanical system that is easy to construct and demonstrates most of the nonlinear effects associated with mechanical systems. The equation of motion for the system is easily derived through a geometrical argument and is found to be Duffing’s equation. The relative strengths of the linear and nonlinear terms can be easily varied and it is possible, in principle, to make the linear term vanish completely. The system is also considered in a driven form. Periodic motions of the system are analyzed theoretically and the results are compared with experiment. Nonperiodic motions are also considered.
Relating mystical concepts to those of physics: Some concerns
Authors: Esbenshade Donald H.
Published: March 2005

Some of the present attempts to emphasize the parallels between mystical concepts and those of physics are listed with a discussion of the reasons for a possible interaction between physics and mysticism. Difficulties with these approaches are considered; some of the related educational or learning aspects for physics are also discussed. It is concluded that efforts to use mysticism to help understand physics are not justified and alternative pedagogical techniques are considered.
Adiabatic invariance of phase volume in some easy cases
Authors: Fernandez-Pineda C. , Diez de los Rios A. , Mengual J. I.
Published: March 2005

A systematic treatment to check adiabatic invariance of phase volume in some easy cases is presented. Systems are classified and studied according to whether or not their Hamiltonian functions depend explicitly on external parameters. When the Hamiltonian function does not depend explicitly on external parameters, some extra hypotheses about the nature of the field of forces in the neighborhood of the walls are needed. In this situation two alternative methods are proposed. One of them uses the virial theorem, the other one uses a kinetic approach.
’’Derivation’’ of the de Broglie relation from the Doppler effect
Authors: Crawford Frank S.
Published: March 2005

Assuming particles possess wave properties, the de Broglie relation is derived by considering elastic reflection from a slowly moving massive mirror.
Simple measurements involving transmission lines
Authors: Holuj F.
Published: March 2005

Undergraduate experiments with transmission lines involving sinusoidal signals and pulses are discussed.
Classical electrodynamics in a universe with two space dimensions
Authors: Lapidus I. Richard
Published: March 2005

Equations for classical electrodynamics in a universe with two space dimensions may be derived directly from those in three space dimensions by beginning with the 3+1 space-time formulation. In 2+1 space-time the electromagnetic field tensor has three independent components corresponding to two components of the electric field and one component of the magnetic field. Several applications of the general equations are discussed.
Measuring optical properties of liquids with a laser
Authors: Jones J. H. , Overcash J. B. , Trostel J. M. , Mandras J. , Chaplin R. L.
Published: March 2005

A spherical 1-l flask that is half-filled with a liquid sample provides an unusual optical system. Light projected by a laser beam can display various symmetrical paths, and the reflections and refractions allow accurate adjustments that offer a practical means for making reliable quantitative measurements of the index of refraction. Polarization of the laser light is discussed and the theoretical and experimental aspects of fluxes are considered.
Parametric solution of the van der Waals liquid–vapor coexistence curve
Authors: Lekner John
Published: March 2005

The van der Waals equation of state together with Maxwell’s equal area rule, leads to a transcendental equation linking the densities of the two coexisting phases. Gibbs solved this in parametric form. We show that the parameter can be chosen to be the difference Δs between the entropy per molecule in the vapour and the entropy per molecule in the liquid. The parametric solution gives, for an arbitrary positive value of Δs, the thermodynamic properties of the two coexisting phases as functions of Δs. The van der Waals coexistence curves are compared with pressure–temperature–density data on He4, Xe, and H2O.
Spatial relations between force and acceleration in relativistic mechanics
Authors: Redding J. L.
Published: March 2005

The lack of parallelism between the force and acceleration vectors has several apparently paradoxical consequences that have been examined recently in the Journal. This article uses a different and more general mode of analysis than previous authors to derive quite general, rather than particular, results.
Statistical interpretation of the local field inside dielectrics
Authors: Barrera Rubén G. , Mello P. A.
Published: March 2005

We analyze and compare several derivations of the Clausius–Mossotti relation that appear in many textbooks. We then present a statistical-mechanical calculation of the local field for a classical system of harmonic oscillators interacting via the Coulomb potential. We derive the Clausius–Mossotti relation in order to analyze consistently the nature of the approximations used and their range of applicability.
Microcomputer data management in an introductory physics laboratory
Authors: Chonacky Norman
Published: March 2005

A microcomputer/mini-floppy disk system is used by students in the laboratory portion of an introductory physics course for science majors. Its purposes are to store their experimental data, do data analyses, and exchange messages with the lab instructor. The system also provides computer-assisted instruction (CAI) simulations of certain lab experiments, and interfaces with measuring equipment in certain experiments. Each student has a personal diskette for data files and basic utility programs for an entire semester. The ease of disk data manipulation under program control is exploited in the following ways: (i) a wide variety of data reduction techniques are introduced that permit quantitative comparisons between experimental results and thoretical expectations; (ii) facile data reduction and analyses permit preliminary processing of experimental data during the course of the lab period, so that decisions cAn be made by students concerning the course of the remainder of the experiment: (iii) accumulated data from various experiments become a course database permitting subsequent analyses of old data adapted in several different logical ways 8e.s. RC circuit data first treated as energy storage, later as one of a number of exponential relationships); (iv) comprehensive course database formed by merging individual student databases sometimes provides the instructor with valuable clues regarding the reliability of experiments. These considerations favor laboratory goals different from the demonstration And confirmation of given physical laws. specifically they inculcate critical thinking and hypothetico-deductive reasoning. I discuss several very real problem areas that plasued this novice and compromised implementation. I compare these problems with the qualitative improvements in laboratory learning.
Motion of a harmonic oscillator with sliding and viscous friction
Authors: Ricchiuto A. , Tozzi A.
Published: March 2005

We present here a method to solve the general equation of a damped harmonic oscillator subjected simultaneously to the resistance of a medium and to sliding friction; it subdivides the motion into single half-cycles. The solutions found, which in particular cases reproduce the well-known ones, have been compared with the results of a typical experiment and satisfactory agreement is found.
Traversing a slippery path in the least time
Authors: Freeman M. , Palffy-Muhoray P.
Published: March 2005

We consider the problem of traversing a slippery path in the least time. Since it is known that the magnitude of the acceleration must be a maximum at all times, the problem is reduced to determining the points where the direction of the tangential acceleration changes. Several illustrative examples are considered.
Particle physics since 1930: A history of evolving notions of nature’s simplicity and uniformity
Authors: Mukherji Viśvapriya , Roy Sudhāṅśu Kumār
Published: March 2005

Pre-1930 atomic physics recognized the proton and the electron alone as the ultimate structural units or ‘‘elementary particles’’ of matter. The belief in the existence of only two kinds of elementaries fitted in well with physicists’ simplistic view of Nature’s frugality. And these two elementaries were found to be charged and ‘‘massy.’’ Hence, most physicists including some leading ones like Bohr and Eddington remained skeptical, for quite some time, towards the hypotheses of the elementarity of the neutrino and neutron. Recognition of these new ‘‘elementaries,’’ according to their viewpoints, would entail two unwelcome implications: firstly, it would jolt the age-old faith in Nature’s simplicity, and secondly, it would mean that the photonic properties, chargelessness and masslessness, could be properties native to any ultimate material particles too. Side by side with this type of skepticism there was, among some theorists, a positivistic reluctance to welcome the invocation of ‘‘unobserved particles’’ in theories. On the other hand, some pragmatic theorists showed bold readiness to introduce unobserved particles for making conceptual breakthroughs. The unexpected and avalanchelike arrival of the so-called superfluons since the late 1940s has, however, given atomic physicists a great jolt and then a new wisdom. They have realized that increasingly sophisticated symmetry and conservation principles must be devised to arrive at a grand unification of diverse subatomic phenomena. They also tend to develop a new conviction that even failures to detect or observe the ‘‘truly’’ ultimate particles in isolation cannot be any evidence against their existence.
Elementary technique to measure the energy band gap and diffusion potential of p
n junctions
Authors: Fischer Charles W.
Published: March 2005

This paper describes three simple experimental exercises suitable for one or more laboratory periods in which the students measure the forward current voltage, the forward rate of change of junction voltage with temperature, and the reverse capacitance voltage characteristics of a pn junction. Using these data the students determine the energy band gap of the semiconductor, the diffusion potential, the ideality factor, and the degree of abruptness of the junction. For these experiments we use junctions fabricated with Ge, Si, GaAs0.6P0.4, and GaP semiconductors. For each of these semiconductors the measured energy band gap is found to be within 5% of the accepted values and the measured junction parameters are consistent with expected values.
A technique for evaluating sums by means of complex integration
Authors: Leavitt Richard P. , Morrison Clyde A.
Published: March 2005

We derive a new technique for evaluating or approximating sums by means of complex integration. Our result is sufficiently general that it is applicable to a wide variety of functions. We consider examples that illustrate the power of the technique: our first example is an alternative derivation of the Euler–Maclaurin sum formula for the case in which the remainder term vanishes, and our other two examples show how our technique can be applied when the Euler–Maclaurin formula is not useful.
The combined effect of mathematics skills and formal operational reasoning on student performance in the general physics course
Authors: Hudson H. T. , Liberman Dov
Published: March 2005

Precourse tests of computational skills in algebra and trigonometry and of formal operational reasoning have been correlated with performance in the algebra-based introductory physics course for 80 students. The correlation coefficient for mathematics and physics was 0.345 (p<0.001) and for formal operational reasoning and physics was 0.435 (p<0.001). However, a multiple regression analysis of the combined effect of mathematics and formal operational reasoning on the total physics grade yielded a multiple R of 0.518, R2=0.268. This study found that the combination of precourse measures of mathematics computational skills and abstract reasoning explained over 25% of the variance in the final physics grade distribution.
Nonlinear resonance in vibrating strings
Authors: Elliott John A.
Published: March 2005

A simple stretched string driven sinusoidally is commonly used to illustrate the concepts of resonance and eigenmodes. In practice, such a system rarely executes planar oscillation, but prefers circular motion. This is shown to be a consequence of the intrinsic nonlinearity of the stretched string oscillator, and the associated parametric coupling between the two transverse polarizations.
Levinson-modified Born approximation as applied to the spherical square well and to Mie theory
Authors: Stein David E. , Green Alex E. S.
Published: March 2005

A modified Born approximation for the spherical square well, incorporating Levinson’s theorem and adjusted energies, extends the range of validity of the conventional Born approximation to include intermediate incident energies and well depths. These modifications also result in accurate Mie phase shifts for the electromagnetic case, for similar ranges of incident energies and effective (or pseudo-) well depths.
Microcomputer as a real-time digital autocorrelator
Authors: Miller Stevens R. , Peterson Mark A.
Published: March 2005

A microcomputer interfaced to a counter can be programmed as a real-time digital autocorrelator. A successful working system is described, together with performance data and examples of applications. This autocorrelator is versatile, inexpensive, and capable of speeds up to 1 ms per channel.
Reflection from dielectric materials
Authors: Reali G. C.
Published: March 2005

This paper deals with the connection of the physical mechanism of reflection, coherent rescattering by a volume distribution of dipoles and the more formal mathematical treatment that can be found in the exposition of Born and Wolf [Principles of Optics, 3rd ed. (Pergamon, New York, 1975)]. After an elementary yet rigorous derivation of the extinction theorem and the Lorentz–Lorenz formula for the index of refraction, it is shown that the reflected field from a dielectric material is not generated just at its surface but comes from everywhere in the interior of it.
Experiments with an impedance tube in the acoustics laboratory
Authors: Rossing Thomas D.
Published: March 2005

Two inexpensive impedance tube designs are described. The theory of acoustic waves in a tube is discussed briefly, including simple equations for acoustic impedance, reflection coefficient, standing-wave ratio, and transmission loss. Ten experiments which make use of the impedance tube are suggested.
The virial theorem and the Dirac H atom
Authors: de Groot E. H.
Published: March 2005

The relativistic quantum-mechanical analog of the virial theorem is formulated and used to solve the Dirac hydrogen atom in a simple way. In this manner the solutions are automatically classified according to the eigenvalues of H, J2, J3, and Q3 where Q3 is the third component of a conserved spin- 1/2 operator, which we call the ‘‘Lenz spin.’’
Energy considerations in connection with a relativistic rotating ring
Authors: Gro/n O/.
Published: March 2005

The retardation of an elastic rotating ring is considered. Bates has formulated a paradox indicating that as the ring slows down, unaccounted for elastic energy appears in the ring. I here show that, due to the relativity of simultaneity, the amounts of work performed at the two ends of a small element of the ring, are unequal, as measured in the instantaneous inertial rest frame of the element. So in addition to the work performed in order to stop the ring, some work is performed which compresses the ring. This work, which vanishes if Galilean kinematics with absolute simultaneity is used, fully accounts for the appearance of elastic energy in the ring.
Slinky oscillations and the notion of effective mass
Authors: Bowen Jeffrey M.
Published: March 2005

Vertical oscillations of a hand-held Slinky spring are investigated. The equation of motion is solved as a Fourier series for general starting conditions. However, it is shown that, for the natural initial condition of dropping from rest, the equation may easily be integrated directly. The resulting motion is periodic with the motion in each period described by a set of second-order polynomials. Finally, the notion of effective mass for the Slinky is investigated.
Resource Letter Q-1: Quarks
Authors: Greenberg O. W.
Published: March 2005

Quarks as fundamental constituents of hadrons play a central role in elementary particle physics. We give an annotated bibliography of references to quarks and related topics in elementary particle physics, as well as to the role of quarks in areas outside elementary particle physics, such as nuclear physics, and astrophysics and cosmology. We label references E (elementary), I (intermediate), and A (advanced) to guide the reader. Articles selected for incorporation in a reprint volume (to be published separately by the American Association of Physics Teachers) are indicated by an an asterisk. A short list of particularly helpful elementary and intermediate references is indicated by a star.
What do ‘‘voltmeters’’ measure?: Faraday’s law in a multiply connected region
Authors: Romer Robert H.
Published: March 2005

A long solenoid carrying a varying current produces a time-dependent magnetic field and induces electric fields, even in the region exterior to the solenoid where ∂B/∂t and therefore curl E vanish. By paying attention to (a) what it is that a ‘‘voltmeter’’ measures and (b) the simplest properties of line integrals (e.g., under what circumstances the line integral of E is path independent), it is easy to use Faraday’s law to predict the readings of voltmeters connected to various points in a circuit external to the solenoid. These predicted meter readings at first seem puzzling and paradoxical; in particular, two identical voltmeters, both connected to the same two points in the circuit, will not show identical readings. These theoretical predictions are confirmed by simple experiments.
Dirac bracket quantization and central force systems
Authors: Kapuscik E. , Uzes C. A.
Published: March 2005

The classical and quantum motions of systems restricted by Dirac second-class constraints are discussed using the Dirac bracket. The discussion is illustrated via a class of constrained central force systems.
Thermal window interferometer
Authors: Ferguson Joe L.
Published: March 2005

Some double-glazed windows produce white-light interference fringes. How can they do that? Such fringes occur only when the superposed waves have an optical path difference of no more than a few wavelengths. This paper points out two different situations which allow multiple reflections, between and within the glass plates, to give the necessary small path difference. In one case the plates must be almost exactly the same thickness and in the other it is sufficient that one of the plates be of nearly uniform thickness.
The effect of gravity on the velocity of sound
Authors: Agrawal D. C. , Menon V. J.
Published: March 2005

The elastic properties of a gas under the action of an external potential field together with the propagation of sound waves in such a medium are discussed in a simple kinetic model. Approximate solutions to the wave equations have been obtained explicitly and the velocity of sound is evaluated in the ‘‘normal region.’’ If the gas is under the action of gravity the square of the sound velocity is shown to decrease linearly with altitude; the velocity in a layer at a given altitude, however, remains constant.
Forced vibration of strings
Authors: Armstrong H. L.
Published: March 2005

The forced vibration of strings has much in common with, on the one hand, their free vibration and, on the other hand, the forced harmonic motion of single objects. But there are also peculiarities, some of which are investigated here. It is found useful to distinguish two kinds of forcing; and some suggestions are made about vibrating strings in such situations as certain teaching experiments.
Time-domain analysis of acoustic transmission by dense thin films
Authors: Lafleur L. Dwynn , Matese John J. , Spross Ronald L.
Published: March 2005

The transmission of a normally incident plane acoustic pulse by a dense thin film is analyzed theoretically in the time domain. The analogy with the RC low-pass filter is noted. Experimental measurements of incident and transmitted acoustic pulses are presented and close agreement with the predictions of the time-domain analysis is obtained. The RC filter analogy is also demonstrated experimentally.
Pressure fluctuations in statistical physics
Authors: Ray John R.
Published: March 2005

We present a detailed discussion of pressure and pressure fluctuations in statistical physics. Among items discussed are the dependence of pressure fluctuations on the wall potential and the existence of a nonthermodynamic quantity in the pressure fluctuation formula.
Exact analytical stochastic model for first-order non-equilibrium phase transitions
Authors: Weaver D. L.
Published: March 2005

The Smoluchowski equation is solved exactly for an asymmetrical double square well potential as a model for first-order nonequilibrium phase transitions.
Some remarks on Faraday’s law
Authors: Rosen Nathan , Schieber David
Published: March 2005

The integral formulation of Faraday’s law, as it is sometimes given, presents some difficulties. Suggestions are made for removing them.
How does the ball-chain work?
Authors: Herrmann F. , Seitz M.
Published: March 2005

A well-known collision experiment can be carried out with an arrangement of several elastic balls suspended in a horizontal row. As we have shown in a previous article a necessary condition for the observed, simple behavior of this arrangement during collision is that the perturbation propagates throughout the system without dispersion. In the present paper, we show that the arrangement can be described by a series of spatially separated masspoints and springs of a special type: the exponent of the force law of the springs is 1.5 according to a theory of H. Hertz. It follows that the first collision sequence of such an experiment is not completely dispersion free. Indeed, slight dispersion during the first collision sequence creates the conditions for the total absence of dispersion in all the subsequent collisions.
Einstein coefficients, cross sections, f values, dipole moments, and all that
Authors: Hilborn Robert C.
Published: March 2005

The relationships among various parameters describing the strength of optical transitions in atoms and molecules are reviewed. The application of these parameters to the description of the interaction between nearly monochromatic, directional light beams and atoms and molecules is given careful attention. Common pitfalls in relating these parameters are pointed out.
Re-examination of the 1887 Michelson–Morley experiment
Authors: Handschy M. A.
Published: March 2005

In 1887 Michelson and Morley presented the results of their now famous experiment that led them to conclude there was no significant relative motion between the earth and the ether. However, the data they published show large systematic trends. Michelson and Morley do not explain how they removed these trends in their analysis. The present work attempts to reconstruct this missing part of the analysis. In addition, modern statistical hypothesis testing and estimation methods are applied to the published data. This new analysis confirms the original null conclusion.
Fourier transforms and the use of a microcomputer in the advanced undergraduate laboratory
Authors: Matthys D. R. , Pedrotti F. L.
Published: March 2005

An experiment using a standard Michelson interferometer and a microcomputer to produce and display Fourier transform spectrograms in the advanced undergraduate laboratory is described. Fourier transforms of laser and mercury light sources, as well as simulated data from a function generator, are presented and discussed. The computer program used is designed to be highly interactive and to allow the student a wide range of performance options.
New correlator–photon counter to illustrate the fundamentals of light statistics
Authors: Basano L. , Ottonello P.
Published: March 2005

A number of instructive demonstration experiments in the field of light statistics are discussed which can be performed using a low-cost time correlator–photon counter designed and built by the authors. A number of basic introductory demonstrations which aim at clarifying the concepts of intensity correlation function, photon-bunching, coherence time, and related topics are briefly illustrated.
Experiences with the artificial kidney as laboratory exercise for students of medicine
Authors: Ambach W. , Rehwald W.
Published: March 2005

A laboratory experiment with an artificial kidney is described. The intention is to stimulate the teaching of elementary physics in premedical education by means of clinical examples. The instructional objective is to provide experiences in handling exponential functions. From graphical representation of the measured data, clearance and membrane permeability of the artificial kidney are calculated. The apparative setup is simple and the costs of the necessary equipment are low.
Different concepts of ‘‘ray’’ in optics: link between resolving power and radiometry
Authors: Koenderink Jan J.
Published: March 2005

Of the many concepts of light rays the most important are the ancient one of Euclid and a more recent one as described by Newton. Euclid’s rays do not carry energy but only describe potentialities for vision of detail. They may be said to carry structural information. Newton’s rays transport energy and form the basis for radiometry. Geometry yields relations dealing with the multitude of rays. In Newton’s interpretation these are radiometric relations, whereas in Euclid’s interpretation these relations deal with resolving power. Thus the partial isomorphism between formulas of radiometry and the theory of resolving power of optical instruments results from simple geometrical relations between line congruences.
Computer graphics for solutions of time-dependent Schrödinger equations
Authors: Chen Robert L. W.
Published: March 2005

Computer graphics has been developed as a teaching aid for an undergraduate course in quantum mechanics. It has the following capabilities: (1) it solves the time-dependent Schrödinger equation and displays the results; (2) the user may interact with the computer program by choosing the initial condition of the wave function, the potential V(x), etc; and (3) it works reasonably fast on computer facilities available in most of the large- and medium-sized colleges and universities.
The Heisenberg picture and the density operator
Authors: Snygg John
Published: March 2005

It is pointed out that the operators P and Q that appear in the Heisenberg picture are the quantum-mechanical analogs of the initial values p0 and q0 that appear in many computations from classical mechanics. It is then suggested that the introduction of a notation which emphasized that point would help students avoid some mistakes that have been made by some very competent physicists.
Standing waves in a string driven by loudspeakers and signal generators
Authors: Clay F. P. , Kernell R. L.
Published: March 2005

The apparatus for demonstrating standing waves in a stretched string has traditionally consisted of a string excited by a fixed frequency vibrator where resonance was achieved by adjusting the tension in the string. This cumbersome approach is alleviated by driving the string with a variable frequency vibrator consisting of a loudspeaker modified with an attachment to grip the string, where the loudspeaker is driven by a variable frequency signal generator. The fundamental string resonance and many harmonics can be located quickly using the described apparatus. If two modified loudspeakers are used to drive the string, the phenomena of beats can also be demonstrated.
Least squares when both variables have uncertainties
Authors: Orear Jay
Published: March 2005

The standard least-squares method should not be applied to those rather common situations where both dependent and independent variables have errors. Instead, the effective variance method should be used. This method and the standard least-squares method are presented, along with a derivation of the general form of the effective variance method.
Momentum propagation by traveling waves on a string
Authors: Benumof Reuben
Published: March 2005

The one-dimensional wave equation for traveling transverse waves on a string implies three interesting consequences. (1) A traveling wave propagates both transverse and longitudinal momentum. (2) The time-rate of change of longitudinal momentum density is equal to the space-rate of decrease of stored energy density. (3) The longitudinal momentum density wave travels with the same speed as the displacement wave but may have a different form. As a result of the transmission of longitudinal momentum, longitudinal forces are exerted on both absorbers and reflectors.
Group-theoretic approach to the Schwarzschild solution
Authors: Wilkes J. M. , Zund J. D.
Published: March 2005

A group-theoretic approach involving Killing vectors and groups of motions is used to derive the static spherically symmetric line element of general relativity.
Effect of the continuum states in second-order perturbation theory: An example
Authors: Coronado M. , Domínguez N. , Flores J. , Portilla C. de la
Published: March 2005

Using a simple example, in which a square-well potential is perturbed by another square-well potential, the effect of the continuum states on the lowest eigenvalue of a one-dimensional Schrödinger equation is evaluated in second-order perturbation theory. We show that this effect decreases when the number of unperturbed bound states grows.
Advanced undergraduate laboratory experiment in inelastic electron tunneling spectroscopy
Authors: White H. W. , Graves R. J.
Published: March 2005

An advanced undergraduate laboratory experiment in inelastic electron tunneling spectroscopy is described. The project was done by junior- and senior-level students. Tunnel junctions were fabricated, the tunneling spectra of several molecules adsorbed on the surface of aluminum oxide measured, and mode assignments made for several of the prominent peaks in the spectra using results obtained from optical studies.
Off-the-mass shell scattering amplitude in a two-particle potential model
Authors: Coutinho F. A. B.
Published: March 2005

In the textbooks of elementary quantum mechanics, two-particle scattering is treated by introducing the concept of off-the-energy shell scattering amplitude. On the other hand, in relativistic quantum field theory, the need to treat momentum and energy on the same footing forces one to use an off-the-mass shell scattering amplitude. We believe the introducing the off-the-mass shell extrapolation of the scattering amplitude in nonrelativistic quantum mechanics should be illuminating. We try to show this in this paper.
Approximate energy levels and sizes of bound quantum systems
Authors: Gersch H. A. , Braden C. H.
Published: March 2005

A simple approximate method using the Heisenberg uncertainty relation and a variational principle is used to obtain energy eigenvalues and corresponding system sizes for a large class of bound quantum systems. Results obtained with this method are compared with exact solutions of the Schrödinger equation.
Influence of air drag on the optimal hand launching of a small, round projectile
Authors: Zufiria J. A. , Sanmartín J. R.
Published: March 2005

Conditions leading to a maximum range for a small, round projectile, fired by hand, are discussed taking into account air drag and the dependence of the initial speed on the mass launched. Both the optimal angle of release for given projectile and initial speed, and the optimal radius for given density (i.e., among a bed of pebbles) are determined; an increase on the height of release is found to always decrease the angle and increase the radius. The influence of the projectile mass on the optimal manner of launching is considered. The validity of the approximations used in the analysis is discussed. Results from very simple measurements show good agreement with theory.
Bohm–Aharonov effect: The quantum mechanics of the electrical transformer
Authors: Danos M.
Published: March 2005

A simple physical picture is presented of the Bohm–Aharonov effect.
Students’ preconceptions in introductory mechanics
Authors: Clement John
Published: March 2005

Data from written tests and videotaped problem-solving interviews show that many physics students have a stable, alternative view of the relationship between force and acceleration. This ’’conceptual primitive’’ is misunderstood at the qualitative level in addition to any difficulties that might occur with mathematical formulation. The misconception is highly resistant to change and is remarkably similar to one discussed by Galileo, as shown by comparison of his writings with transcripts from student interviews. The source of this qualitative misunderstanding can be traced to a deep-seated preconception that makes a full understanding of Newton’s first and second laws very difficult. In such cases learning becomes a process in which new concepts must displace or be remolded from stable concepts that the student has constructed over many years.
Regression line analysis
Authors: Krane K. S. , Schecter L.
Published: March 2005

A computational technique is presented, suitable for small computers, of doing regression line analysis on data independent uncertainties.(AIP)
Resource Letter SE-2: Solar Energy
Authors: Hodges Laurent
Published: March 2005

This resource letter provides a source of information about the main types of solar energy and their uses, updating Resource Letter SE-1 issued seven years ago. It is intended for the use of high school and college teachers both in developing courses and in guiding students to the literature of solar energy applications. Articles marked with an asterisk have been selected for publication in an accompanying reprint book. The letter E after the reference number denotes a relatively elementary item, useful for high school and introductory college use and the educated public; the letter I denotes intermediate level references, sophomore to senior level; and the letter A denotes advanced material, principally for senior and graduate-level courses.
Role of the observer in quantum mechanics and the Zeno paradox
Authors: Singh Ishwar , Whitaker M. A. B.
Published: March 2005

We discuss the role of the observer in quantum mechanics. We briefly discuss various interpretations of quantum-mechanical measurement currently used in the literature. Then we point out the difficulty in deciding what occurrences should be classified as ’’observations.’’ Using the Copenhagen Interpretation, we discuss the effect of successive measurements on the decay rate of an unstable quantum system. For two types of systems, those with a small finite number of decay levels and those with a continuum or semicontinuum, we review the decay behavior, and in the latter case distinguish between: small time behavior, with survival probability falling off as t2; the intermediate region, where it varies exponentially with time; and the long-time region, where the decay is less than exponential. If we cannot define an observation, we show that only an exact exponential decay is allowed. Attempts at solutions of this difficulty are mentioned. Lastly, we take an example of a polarized beam of light passing through an optically active medium, and discuss the process of successive measurement from classical and quantum mechanical viewpoints. The two descriptions appear to differ because we are implicitly considering two different experimental arrangements. We put forward classical and quantum-mechanical descriptions of each experiment.
Flexible string in special relativity
Authors: Holstein Barry R. , Swift Arthur R.
Published: March 2005

The relativistic transformation laws for force imply that a moving string, no matter how flexible, may exert a force perpendicular to its length.
A linear Fick’s law calorimeter
Authors: Alpert Seymour S. , Bryant Pat D. , Woodside William F.
Published: March 2005

A small animal calorimeter is described that is based on the direct application of Fick’s law. Heat flow is channeled through a circular disk of magnesium and the temperature difference between the inside and outside surface of the disk is detected by means of solid-state temperature transducers. The device is calibrated using a light-weight electrical resistive source and is shown to be linear in its response and to have an e-folding time of 4.8 min. A rat was introduced into the calorimeter and its heat energy expenditure rate was observed in both the sedated and unsedated states.
Quantum-mechanical scattering in two dimensions
Authors: Lapidus I. Richard
Published: March 2005

Nonrelativistic quantum-mechanical scattering in two dimensions is discussed. Two approximation methods—partial waves and the Born approximation—are presented with examples.
Advanced laboratory NMR spectrometer with applications
Authors: Biscegli Clovis , Panepucci Horacio , Farach Horacio A. , Poole Charles P.
Published: March 2005

A description is given of an inexpensive NMR spectrometer that is suitable for use in an advanced laboratory course. The application of this spectrometer to the measurement of the oil content in corn seeds and the role of polymerization are presented.
Phenomenology and logical reasoning in introductory physics courses
Authors: Arons A. B.
Published: March 2005

Specific illustrations are given of questions and problems designed to lead students in introductory courses into visualizing, and reasoning qualitatively about, physical phenomena.
Variational approximation to the spectra of systems with confining potentials
Authors: Fernández Francisco M. , Castro Eduardo A.
Published: March 2005

A new simple variational method is proposed. Such a method is wholly rigorous from a formal point of view and it enables us to obtain upper bounds for eigenvalues of physical systems. It is shown that energy eigenvalues calculated in an approximate fashion with trial functions that satisfy the quantum virial theorem, have an identical behavior as that deduced from the WKB method. Numerical results are compared with exact ones.
The inverted pendulum: A mechanical analog of the quadrupole mass filter
Authors: Friedman M. H. , Campana J. E. , Kelner L. , Seeliger E. H. , Yergey A. L.
Published: March 2005

The inverted pendulum is shown to be an analog of the quadrupole mass filter. The theory of the inverted pendulum is developed and the design criteria for a working model are presented. The working model is used to experimentally measure the β parameter from Mathieu function theory. These measurements are discussed with respect to the theory. Finally, the similarities in the operation of the quadrupole mass filter and the inverted pendulum are discussed.
Direct measurement of the helicity of the muonic neutrino
Authors: Roesch L. Ph. , Telegdi V. L. , Truttmann P. , Zehnder A. , Grenacs L. , Palffy L.
Published: March 2005

We describe a simple experiment for measuring the helicity of the muonic neutrino, hνμ, directly. This experiment is the muonic analog of the celebrated Brookhaven experiment for the electron neutrino. Both are based on measuring the longitudinal polarization PL of the recoils in a 0→1 lepton capture; here we exploit 12C(μ−, νμ)12B(g.s.), determining the polarization of 12B through its β-decay asymmetry. Recoils going into a specific hemisphere are chosen by the trick of ’’selective implantation.’’ The paper includes an elementary derivation of the requisite theoretical expressions. We find hνμ = −1.06(11), i.e., −1.0 with considerable accuracy.