bluuebunny/crossref_metadata_2025 huggingface dataset:
Double-group theory on the half-shell and the two-level system. II. Optical polarization
Authors: Harter William G. , dos Santos Narciso
Published: March 2005

Relations are derived between several different descriptions of optical polarization by analogy to the theory of spin 1/2. The rotational slide rule developed in the preceding article (I) is used to (a) compute the final polarization state and phase of an optical beam given the optical wave matrix, initial state, and phase, (b) make conversions between various types of polarization parameters, and (c) find the output intensity for perfect polarizers. Other polarization problems and methods are discussed briefly.
Measurement of acoustical second-order Doppler effect as an introductory experiment to special relativity
Authors: Schiel D. , Slaets J. , Mascarenhas S.
Published: March 2005

A different approach is suggested for introducing special relativity. This approach exploits the distinction between the Doppler effect for sound and for light. With the Doppler effect for sound the difference in the frequency when the observer is in motion is not the same as when the emitter is in motion. This is exhibited already in the second order for sound, but for light there is no such shift in any order. An experiment suitable for an advanced undergraduate laboratory has been designed which can detect this second-order difference in the acoustical shift. The system oberver (microphone) or emitter (loudspeaker) is mounted on an air track and measurement is made with a specially built frequency meter. The theoretical expression for the shift was confirmed in our laboratory for speeds from 3 to 7 m/s at an emitted frequency of 40 kHz.
Laboratory study of the radioactivity from fission products in microscopic fallout particles
Authors: Smith H. A. , Ward T. E. , Wesick J.
Published: March 2005

An experiment is described wherein simple γ-ray detection and analysis techniques were utilized to study the radioactivity in local precipitation. Gamma spectra from filtered particulate, evaporation residue, and water from a sample of freshly fallen snow were counted, and the relative amount of several radionuclides present were identified. These data show that several isotopes produced in the recent Chinese nuclear detonation (Lop Nor testing ground, Sinkiang Province, 17 November 1976) are observable. Furthermore the data are sufficient to estimate the date of the detonation and to determine some of the characteristics of the explosion.
Square-wave model for a pendulum with oscillating suspension
Authors: Yorke Ellen D.
Published: March 2005

If a sinusoidal oscillation of the point of support of a pendulum is approximated by a square wave, a matrix method may be used to discuss parametric resonance and the stability of the inverted pendulum.
Thermodynamic work on a harmonic oscillator
Authors: Edmonds James D.
Published: March 2005

The harmonic oscillator is examined as an example of a thermodynamic system with properties analogous to the ideal gas at high temperatures, but better behaved as T→0° K. The concept of PdV work is examined in the generalized context of the oscillator ’’pressure.’’
The precessing spherical pendulum
Authors: Olsson M. G.
Published: March 2005

The spherical pendulum offers an excellent opportunity to observe nonreentrant orbits with next to no experimental apparatus. A relatively straightforward theoretical analysis shows that for small displacements the elliptical orbit will precess at a rate proportional to its area.
Aharonov-Bohm scattering by a thin impenetrable solenoid
Authors: Corinaldesi E. , Rafeli F.
Published: March 2005

Aharonov and Bohm constructed a wave function describing scattering of electrons by an impenetrable solenoid, from which they derived a cross section of the form dσ/dϑ = g (ϑ)sin2(πα), where ϑ is the scattering angle and α is a coupling constant. A simplified version of their work is presented, together with an attempt to obtain by Born approximation the approximate expression dσ/dϑ ? g (ϑ) π2α2 small α. It is explained why such an attempt is unsuccessful.
Demonstration of phase transition and properties of metallic glasses for undergraduates
Authors: Anderson P. M. , Lord A. E.
Published: March 2005

Simple and inexpensive (?$10) demonstrations of some properties of metallic glasses are presented. Metallic glasses are new materials of intense current scientific and engineering interest. The viscoelastic behavior is observed during the phase transition from amorphous to crystalline states. Comparisons are made of some mechanical, electrical, and magnetic properties between the two states. It is hoped that this note can generate interest in the undergraduate community toward working in current research areas.
Undergraduate experiment on noise thermometry
Authors: Kittel P. , Hackleman W. R. , Donnelly R. J.
Published: March 2005

An absolute temperature scale noise thermometer is described and Boltzmann’s constant is measured. The apparatus involves an easily constructed temperature probe and standard electronic instruments. The design considerations for the experiment are a useful introduction to low noise electronics.
Newtonian mechanics and the human body: Some estimates of performance
Authors: Lin Herbert
Published: March 2005

Non-trivial but elementary numerical examples of basic mechanics are lacking in most introductory textbooks. This paper gives several very simple examples which relate to numbers for which many students already have some intuition. In particular, we estimate the speeds of running, cycling, and walking, the length of a good broad-jump, the heights of a polēvault and a vertical high jump from rest, and the time for running up a flight of stairs. These estimates and the observed numbers are found to match rather well.
EER, COP, and the second law efficiency for air conditioners
Authors: Leff Harvey S. , Teeters William D.
Published: March 2005

It is pointed out that there is a close relationship between the energy efficiency ratio (EER) of an air conditioner unit and the coefficient of performance (COP) of its refrigeration cycle. This connection helps to bridge the gap between pure thermodynamics and practical energy-related problems. In this spirit, two other efficiency parameters, the total COP and total EER, measured relative to the energy extracted by a primary energy source (e.g., a fossil fuel), are defined. A comparison of the actual total COP (or total EER) relative to its maximum allowed value, consistent with the second law of thermodynamics, leads to an estimate for air conditioners of the recently proposed second law efficiency.
Quantization of radiant energy in waveguides
Authors: Raudorf Walter R.
Published: March 2005

The electromagnetic field within a waveguide is described in terms of an infinite discrete set of variables which permits the application of the formalism of quantum mechanics. The quantized field exhibits potential energy which depends on the structure of the guide and the mode of the field but not on the frequency. The radiant energy experiences a compression during the transition from one guide into another one of smaller cross section.
Principle of equivalence and the deflection of light by the sun
Authors: Comer Robert P. , Lathrop John D.
Published: March 2005

We review the usual principle-of-equivalence calculation for the deflection of light by the sun, which fails to give the general relativistic answer. We show that the discrepancy arises because, by construction, this calculation can in fact only yield the deflection relative to the trajectories of infinitely fast particles (purely spatial geodesics). The total deflection is thus the sum of the deflection given by the principle of equivalence and the deflection of infinitely fast particles. We verify this result, which we extend from the case of photons to fast particles in general, by direct calculation.
Students’ scores on Piaget-type questionnaires before and after taking one semester of college physics
Authors: Barnes George , Barnes George Bruce
Published: March 2005

This paper reports the results of a study designed to measure any change in the Piagetian level of intellectual functioning of students in introductory physics classes over a period of one semester. The classes selected for the study contained students in premedical and engineering physics. Using the most powerful appropriate statistical test, no significant change was found, although there was a tendency for the pre-course scores to be slightly higher than the post-course scores. Furthermore, changes in scores considerably greater than those observed would not have been statistically significant.
Experiments on the photoelectric effect and on the diffusion of electrons in gases
Authors: McClellan G. , Didwall E. M. , Rigby Cornel J.
Published: March 2005

A versatile appartus for observing the behavior of photoelectrons in a uniform magnetic field in either a vacuum or a low-pressure gas is described. The apparatus was designed and constructed as a senior research project and is now used in a graduate laboratory course. Data on work functions and the photoelectron energy and angular distributions are presented and a common misinterpretation of photoelectric work functions is discussed. Data on the diffusion of free electrons in low-pressure air are compared to a series solution of the steady-state diffusion equation to determine the electron-molecular total cross section. The interpretation of cross sections from diffusion experiments is discussed.
Kepler problem and Maxwell fish-eye
Authors: Buchdahl H. A.
Published: March 2005

In a certain sense the theory of the Maxwell fish-eye and that of the Kepler problem are formally equivalent. This equivalence and its consequences are described in some detail.
Teaching the exclusion principle with philosophical flavor
Authors: Shadmi Y.
Published: March 2005

An approach to the teaching of the chapter ’’Equivalent particles and the exclusion principle’’ (which is part of an undergraduate quantum mechanics course) is outlined. The clarification of basic concepts and the preventive treatment of anticipated beginners’ misunderstandings are emphasized. The exclusion principle is taught by confronting it with the principle of the ’’identity of the indiscernible’’ of Leibnitz. The limits of the analogy between general ideas belonging to different disciplines are outlined by discussing the inability of philosophy to predict the directions in which the physical theory actually advances.
Mechanics of a chain of dominoes
Authors: Shaw D. E.
Published: March 2005

An experiment involving a linear chain of falling dominoes is discussed. The time for a chain of N equally spaced dominoes to fall is measured accurately using simple equipment. The experimental data is compared with the predictions of theory. The experiment is suitable for either an introductory or intermediate undergraduate level depending upon the analyses required.
Teaching the renormalization group
Authors: Maris Humphrey J. , Kadanoff Leo P.
Published: March 2005

The renormalization group theory of second-order phase transitions is described in a form suitable for presentation as part of an undergraduate statistical physics course.
Length paradox in relativity
Authors: Martins Roberto de A.
Published: March 2005

The apparent self-contradictions of special relativity in thought experiments, where a body is intended to traverse a slit, do not have so simple a solution when that object is three-dimensional as when it is an idealized one- or bi-dimensional body. We use a special case of this new kind of situation in order to exemplify the general method whereby any such paradox may be analyzed and shown to be no real contradiction.
Construction of Lagrangians and Hamiltonians from the equation of motion
Authors: Yan C. C.
Published: March 2005

It can be demonstrated that corresponding to a given equation of motion one can construct infinitely many Lagrangians and Hamiltonians. Hence the question of selecting a correct Lagrangian or Hamiltonian arises. However, owing to the lack of an established criterion, the choice at present is largely a matter of taste and art.
Diurnal motion of the Sun as seen from Mercury
Authors: Turner Lawrence E.
Published: March 2005

The quantitative description of the motion of the Sun as observed from Mercury is a problem suitable to a variety of classes. The only difficult aspect for introductory students is a determination of the position along the orbit for the planet. Two methods are described and a listing of a computer subroutine is included. The combination of slow rotation and high eccentricity of Mercury’s orbit makes this problem an interesting one.
Padé approximants via the continued fraction approach
Authors: Sullivan J.
Published: March 2005

The Padé approximant technique has emerged as a powerful mathematical aid for treating certain physical problems. Often, however, students are not aware of the technique or its uses. A grasp of the method can be obtained from the continued fraction approach, which in one aspect is a subset of the Padé technique. Continued fractions and the more familiar power series method both depend on an unknown remainder term. The quantitative difference is that for many functions, the dependence of the continued fraction on the remainder term is very slight. This paper illustrates the continued fraction approach, mainly by example. Two idealized versions of quite different physical problems are first treated. Then the technique is applied to a numerical example and finally, to a more mathematical type of question.
Electromagnetic showers at high energy
Authors: Loos J. S. , Dawson S. L.
Published: March 2005

Electromagnetic showers induced by 1.57-GeV e+ particles incident on a tantalum plate have been studied in a bubble chamber experiment. These showers illustrate many of the interesting properties of bremsstrahlung, e+e− pair production, Compton scattering, and other quantum phenomena. Some detailed comparisons between experiment and theory are made by using computer-generated simulations of electromagnetic showers.
Design and construction of simple, nitrogen-laser-pumped, tunable dye lasers
Authors: Hilborn Robert C.
Published: March 2005

The basic physical principles of dye lasers are discussed and used to analyze the design and operation of tunable dye lasers pumped by pulsed nitrogen lasers. Details of the design and construction of these dye lasers are presented. Some simple demonstration experiments are described.
Noise emission from laboratory air blowers
Authors: Rossing Thomas D. , Windham Betty
Published: March 2005

Product noise ratings for a number of laboratory air blowers are reported, and several recommendations for reducing laboratory noise from air blowers are given. Relevant noise ratings and methods for measuring noise emission of appliances are discussed.
Cohesion of bubbles in foam
Authors: Ross Sydney
Published: March 2005

Single bubbles cohere into a cluster with a reduction of free energy that depends on their size, surface tension, and final shape, as well as on the temperature and the external pressure. Let the initial state be a set of uniform spheres, and the final state an idealized cluster composed of the same number of uniform polyhedra; the free-energy change, or binding energy, is calculated on the basis of one mole of gas, and likewise on the basis of a single bubble going from sphere to polyhedron. Some new relations of bubble geometry are developed in the course of the calculation.
Stability of the physicist’s image
Authors: Fraser Barry J. , Remenyi Andrew G.
Published: March 2005

A study of the physicist’s image revealed that : (a) school students held a more favorable image of the physicist than did university students or school teachers and (b) that the image of the physicist, unlike several other occupations investigated, remained remarkably stable when information about the nature of the physicist’s work was provided.
Motion of an electron wave packet in a uniform electric field
Authors: Churchill John N.
Published: March 2005

Energy eigenstates are superimposed in order to form the wave packet for an electron propagating in one dimension under the influence of a uniform, time-independent electric field. Flux velocity, phase velocity, and envelope velocity are considered. Asymptotic expressions are derived which describe the motion when the electric field is small and/or the wave packet is far away from the classical turning point. A graphical method is presented by which one can obtain both the position and shape of the envelope at a time t if the position and shape are known at some initial time.
Resource Letter ENC-1: Environmental noise control
Authors: Rossing Thomas D.
Published: March 2005

Prepared at the request of the AAPT Editoral 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, Kenyon College, Gambier, Ohio 43022. Notation: The letter E after an item number indicates elementary level; the letter I indicates intermediate level; and the letter A indicates advanced material. An asterisk (*) indicates those references we feel to be especially helpful. Reprints: When ordering, request Resource Letter ENC-1. Enclose $0.75 per copy (not in stamps) together with a stamped and self-addressed envelope and send to Publications Department, American Association of Physics Teachers, Graduate Physics Building, SUNY at Stony Brook, Stony Brook, New York 11794.
Gauge invariant formulation of the interaction of electromagnetic radiation and matter
Authors: Kobe Donald H. , Smirl Arthur L.
Published: March 2005

The conventional perturbation theory in quantum mechanics for the interaction of electromagnetic radiation with matter, which is based on the time-dependent vector and scalar potentials, is shown to be dependent on the gauge. The problem is reformulated, using the approach of Yang, in a gauge-invariant way, in which the transitions between states are induced by the quantum-mechanical power operator. In order to use an unperturbed Hamiltonian which does not involve the electromagnetic field, the gauge is chosen to give the electric dipole interaction. This choice can be made if the magnetic field is negligible and the electric field is slowly varying over atomic dimensions. For a comparison of the gauge-invariant and conventional formulation, a two-level atom in a radiation field is considered. For the probability that an atom originally in the lower state will make a transition to the upper state when the field is not in resonance, the gauge-invariant formulation gives the correct result, whereas the gauge-dependent formulation gives an incorrect result.
An undergraduate experiment to measure the reflectances of a dielectric surface
Authors: Driver H. S. T.
Published: March 2005

This paper describes an experiment for the measurement of the reflectances of a dielectric surface. The experiment is analyzed in terms of the Stokes parameters and the Mueller calculus, and a generalized form of Malus’ law is derived. The results for the reflectances of glass of refractive index 1.53 are in satisfactory agreement with the theory based on the Fresnel amplitude reflection relations. In addition to illustrating this aspect of electromagnetic theory, the experiment provides an introduction to the properties of real linear polarizers.
Einstein’s ideas: A course on special relativity for general students
Authors: Fishbone Leslie G.
Published: March 2005

All of the peculiar kinematical effects of special-relativity theory can be rigorously derived by means of ordinary algebraic methods. For this reason, highly motivated students with a minimal mathematical background are capable of understanding special relativity given a careful exposition of the theory and (filmed) demonstrations of the theory’s experimental predictions. We supply these ’’givens’’ in a successful course for general students at the University of Utah.
Solving spin-1 problems using spin-1/2 methods
Authors: Weaver D. L.
Published: March 2005

It is shown how many problems involving aspects of spin-1 matrix algebra may be handled in a way analogous to the spin-1/2 algebra of the Pauli matrices. A number of examples of the main point are given in illustration.
Teacher effectiveness: Self-determined change
Authors: Aubrecht Judith D.
Published: March 2005

This study was designed to explore the feasibility of establishing observer-teacher relationships at the university level and to test the usefulness of observation data to university teachers. Part I (carried out in the spring of 1972) dealt with the questions: (1) Does a teacher’s classroom behavior change after he receives systematic observation data? and (2) If so, what are the characteristics of the change? Part II (carried out in the spring of 1975) dealt with the questions: (1) Why does a teacher desire to make specific changes in classroom behavior? and (2) How does a teacher produce desired changes?
Quasi-Carnot cycles, negative Kelvin temperatures, and the laws of thermodynamics
Authors: Tykodi R. J.
Published: March 2005

It is maintained that the impossibility of moving a thermodynamic system adiabatically and reversibly (isentropically) from the domain of positive Kelvin temperatures to the domain of negative Kelvin temperatures (and vice versa) is a consequence of (an extended form of) the Third Law of thermodynamics and not of the Second Law alone; it is further maintained that Schöpf’s apparent proof to the contrary is inconclusive. In the course of the discussion the properties of a quasi-Carnot cycle (two adiabatic steps coupled with two steps involving floating temperature heat reservoirs) are explored.
On the nature of the Hamiltonian for the interaction of radiation with atoms and molecules: (e/m
c)p⋅A, −μ⋅E, and all that
Authors: Power E. A. , Thirunamachandran T.
Published: March 2005

In nonrelativistic quantum electrodynamics there is a class of equivalent Hamiltonians that describe a system of radiation and atoms or molecules in interaction. Three specific examples, namely, the minimal coupling, the multipolar, and the space-translated forms are analyzed here in detail. Their equivalence is demonstrated. The Lagrangian approach has also been examined to give further insight into the dynamics. The equations of motion are compared. Finally, the process of two-photon absorption by an atom is used as an application of the various interaction Hamiltonians in a discussion of their computational differences.
Baccalaureate program in medical physics
Authors: Chopp Michael , Liboff A. R.
Published: March 2005

One category of applied physics presently of great interest is medical physics; in large measure this is due to the increasingly rapid transfer of physical concepts and techniques to the area of health care. The traditional entrance to the medical physics profession is at the master’s level. A four-year baccalaureate applied physics program is described, which, among other things, provides preparation for specialized graduate study in this field. Increased material in chemistry and biology is required as well as work in radiological physics, the latter conducted partly in a hospital setting.
Dynamics of a bicycle: Nongyroscopic aspects
Authors: Liesegang J. , Lee A. R.
Published: March 2005

Elementary analysis of the equations of motion of a bicycle lead to considerations which affect the design of bicycles for use under different conditions. The analysis is also applied to clarify a well-known lecture demonstration.
A new method for observing steady-state vibrations at liquid-air interfaces
Authors: Jacobson D. M. , Kaplan B. Z.
Published: March 2005

A new method of studying steady-state resonant vibrations at liquid-air interfaces, using recently developed ferrofluids, is described. In such liquids it is possible to set up vibrations by external magnetic fields alone. An arrangement incorporating such a system may be used to demonstrate resonances in the liquid and to study the mixing of magnetic forces at different frequencies.
Critique of the treatment of work
Authors: Canagaratna S. G.
Published: March 2005

The difficulties in the treatment of work are discussed. It is shown that it is useful to distinguish between the work done by the work source and the work received by the system. The former is in general greater than the latter. This inequality should be carefully distinguished from the inequality that compares the work received by the system in a change carried out quasistatically with the corresponding quantity for the same change carried out nonstatically. The conditions under which these two quantities may be compared are carefully examined. It is shown that in the general nonstatic case the work cannot be calculated in mechanical terms alone; we have to use the first law of thermodynamics.
Note on the time-dependent damped and forced harmonic oscillator
Authors: Leach P. G. L.
Published: March 2005

A Hamiltonian for the time-dependent damped and forced harmonic oscillator is derived. A simple time-dependent linear canonical transformation transforms the Hamiltonian to one whose solution is readily obtained. The wave function for the corresponding quantum mechanical problem is given.
Elementary computer physics, a concentrated one-week course
Authors: Christiansen Gunnar
Published: March 2005

A concentrated one-week course (8 hours per day in 5 days) in elementary computer physics for students in their freshman university year is described. The aim of the course is to remove the constraints on traditional physics courses imposed by the necessity of only dealing with problems that have simple analytic solutions. Thus it will be shown that insight into the solutions of rather complex problems can be gained by numerical experimentation and that expensive laboratory experiments may be simulated by computer experiments. A harmonic oscillator, a charge in crossed electric and magnetic fields, and a lunar space vehicle are used as examples.
The physics of a push-me pull-you boat
Authors: Blackford B. L.
Published: March 2005

The basic laws of mass, energy, and momentum conservation are applied to a novel wind-driven water craft. The resulting analysis is an instructive application of these laws, suitable as an undergraduate physics exercise. We find a critical condition which must be met before the boat will accelerate against the wind, and we also obtain expressions for calculating the final speed.
A simple, accurate alternative to the minimum-deviation method for the determination of the refractive index of a prism
Authors: Waldenstro/m S. , Naqvi K. Razi
Published: March 2005

An alternative to the classical minimum-deviation method for the determination of the refractive index of a prism is proposed, and its advantages are outlined. Though devised primarily for pedagogic purposes, the new ’’fixed angle of incidence method’’ may find applications in research.
Translational invariance of waveguides and normal modes
Authors: Vassallo C.
Published: March 2005

The linearity and the translational invariance of waveguides give a natural way to go from the Green’s function concept to the normal mode concept. It is pointed out that the completeness of normal modes depends on the good behavior of the Fourier transform of the Green’s function at infinity in the complex plane of propagation constants.
Experiment with the individualized laboratory system
Authors: Lagendijk E. , Niesten P. T. M. , van Willigen W. , Wolthers W.
Published: March 2005

A comparative experiment was carried out with two teaching forms of an introductory laboratory course for freshmen in physics. The results indicate that an individualized version of the course is more effective than a traditional version. The individualized version turns out to be more efficient in learning time but less efficient in teaching time per student. On the average, the students do not differ in their opinion about the attractiveness of the two versions, but the students of the individualized version think that they have spent their time more usefully than the students of the traditional version. There is some indication that the traditional version reinforces an existing positive attitude towards physics experimentation more than the individualized version does. Observations of students doing experiments in the traditional version of the course suggest that these experiments emphasize concrete aspects of experimentation, which may hamper the development of formal skills necessary for good experimental work.
The Physical Sciences Building at Washington State University
Authors: Dresser Miles J. , Butler Alfred B.
Published: March 2005

The Physical Sciences Building at Washington State University is a 16-story structure that cost 8.5 million dollars. It was completed in January 1974 and is occupied by the Departments of Physics and Geology. Features in the lecture halls include overhead projection for the major presentation format with at least two used in each room, regular slide or movie projection from the rear, student seating on individual pedestal chairs with a continuous table for each row, and demonstrations that are changed by rolling tables from the front exit of the lecture hall directly to the preparation area. The research and teaching labs were designed principally from the viewpoint of flexibility for changing needs. A review of the success of these designs is made from the vantage point of three years of occupancy.
Uniqueness of Maxwell’s equations
Authors: Cohn Jack
Published: March 2005

As a consequence of two feasible assumptions and close attention being given to the definitions of charge and the fields E and B, it is shown that the lowest-order equations that these fields must satisfy are Maxwell’s equations.
The ball bearing as a motor
Authors: Gruenberg) H.
Published: March 2005

When a current is passed through a ball bearing it can act as a motor. This curious effect was pointed out by Milroy. The present paper gives a theoretical analysis of this effect. The motor can run in either direction on both dc and ac. It can be self-starting on dc. Some experimental results are presented in support of the theory.
Heat of sublimation of I2 by laser photometry
Authors: Henderson Giles , Robarts Ronald A.
Published: March 2005

An inexpensive double-beam laser photometry experiment is described to determine the molar heat of sublimation of I2. The experiment employs common laboratory materials and components and gives results with a 2% to 3% accuracy.
An elementary application of exterior differential forms in quantum mechanics
Authors: Hoshino Yoshiaki
Published: March 2005

A simple method of calculating the orthogonal curvilinear coordinate representations of quantum mechanical operators is presented in terms of exterior differential forms.
Random walks, the Ornstein-Zernike equation, and the condensation of a one-dimensional lattice gas
Authors: Robledo Alberto , Budgor Aaron B.
Published: March 2005

We present an alternative and simpler derivation of the equation of state of the Van der Waals type for a one-dimensional lattice gas model where the pair interaction between the molecules is the Kac potential in the Van der Waals limit. The treatment is based on the existing analogy between the Ornstein-Zernike equation and the lattice Green’s function equation governing a random walk on a lattice. The Maxwell equal-area construct follows from two simple assumptions regarding a particle performing a random walk in a two-phase system.
Shubnikov–de Haas oscillations in a degenerate semiconductor
Authors: Mansfield R.
Published: March 2005

A third-year undergraduate experiment for measuring the Shubnikov–de Haas oscillations in indium antimonide is described. It provides a useful introduction to low-temperature techniques and to cryomagnetic systems and is an instructive example of the type of experiment carried out currently in solid-state physics. The equipment required is relatively inexpensive and is widely available in many laboratories. Some projects based on this experiment are also mentioned.
Calculation of linear coefficients in irreversible processes by kinetic arguments
Authors: Lachish Uri
Published: March 2005

The linear coefficients are calculated by kinetic arguments and the ’’Onsager reciprocity theorem’’ is verified for two systems. One is the gas flow between two containers at different pressures and temperatures, and one is the gas flow along a pipe wih pressure and temperature gradients.
An example of branching in a variational problem
Authors: Darbro Wesley
Published: March 2005

A model for the shape a liquid takes due to its surface tension while suspended upon a wire frame in zero-g is solved by use of Lagrange multipliers. It is shown how the configuration of soap films so bounded are dependent upon the volume of liquid trapped in the films. A special case of the solution are the soap films naturally formed on a cubical wire frame.
Forgotten fundamentals of the energy crisis
Authors: Bartlett Albert A.
Published: March 2005

’’Facts do not cease to exist because they are ignored;’’ Aldous Huxley.
Derivation of the perturbation formulas for the energy in quantum mechanics
Authors: Gottdiener Luis
Published: March 2005

A method to derive the formulas for the energy appearing in the Rayleigh-Schrödinger perturbation theory in quantum mechanics is presented. The procedure, which we consider to have some advantages over the usual approach, aims at solving the secular equation D (E) =0. The first-, second-, and third-order formulas are derived by this method.
Expansion of the universe and a hierarchical structure of the universe as solutions of the dark night sky paradox
Authors: Gro/n O/.
Published: March 2005

It is shown that the expansion of the universe alone and a hierarchical structure of the universe alone may solve the dark night sky paradox. Also it is pointed out that in the actual universe Harrison’s solution and the expansion of the universe are of about the same importance in reducing the radiation density to the level we observe by night, while the hierarchical model of the universe does not correspond with our universe as we know it today.
Forces giving no orbit precession
Authors: Brown Lowell S.
Published: March 2005

We show that particles moving in a central force move in closed nonprecessing orbits only if the force law is of the inverse square (Coulomb) or linear (harmonic oscillator) type.
Autobalancing radiometer
Authors: Wieder Sol , Jaoudi Edmond
Published: March 2005

The concept of electrical compensation in bolometric radiometers is discussed. The autobalancing radiometer is considered in detail and its construction and calibration are described. An insolation recording taken with this radiometer is compared with the heat per unit area collected by a flat plate collector.
The goose chase
Authors: Behroozi F. , Gagnon R.
Published: March 2005

The case of a farmer chasing his stray goose is considered from the point of view of a physicist. It is shown that the best strategy for capturing the goose is to arrange for a head-on encounter. The physics involved fits well in an upper level mechanics course, and helps to elucidate several important concepts.
Fraunhofer diffraction and polarization
Authors: Fortin E.
Published: March 2005

An experiment for the intermediate undergraduate optics laboratory is described which demonstrates the effects of the polarization of light on a double-slit Fraunhofer diffraction pattern. The experiment serves to illustrate in a single study the phenomena of diffraction, interference, coherence, some aspects of apodization, the Fresnel-Arago law, as well as some of the interrelations between these concepts.
Energies of screened Coulomb potentials
Authors: Lai C. S.
Published: March 2005

By applying the Hellman-Feynman theorem alone to screened Coulomb potentials, it is shown that the first four coefficients in the energy series as powers of λ/Z can be obtained from quantities of the unperturbed Coulomb system.
Points of equilibrium in electrostatic fields
Authors: Rogers Peter J.
Published: March 2005

The electrostatic field of a system of coplanar static charges is often represented by electric field lines in the plane of the charges. However, where points of equilibrium are involved and the electric field line density is used as an indication of the electric field intensity, care must be taken in interpreting the field pattern. The field line density must always be determined three dimensionally. In some situations field lines in the plane of the charges converge on a point of zero charge, a neutral point or point of equilibrium. Gauss’s Law is not violated in these circumstances. One example is considered.
Uncertainty relation between angular momentum and angle variable
Authors: Roy C. L. , Sannigrahi A. B.
Published: March 2005

Certain pitfalls regarding the uncertainty relation between angular momentum and the angle variable have been discussed from a didactical point of view. Further, an uncertainty relation has been derived for these variables in a simple and consistent manner; this relation is valid only for small values of uncertainty in the angle variable.
Vibrations of a one-dimensional defect lattice
Authors: Kesavasamy K. , Krishnamurthy N.
Published: March 2005

The lattice vibrations of a monatomic chain containing a substitutional impurity is investigated in detail, assuming a molecular model. The normal modes of a penta-atomic molecule, formed of the impurity and its neighboring host atoms, and vibrating in the potential field set up by the static lattice, bring out clearly the important properties of the defect lattice.
Fourier treatment of near-field scalar diffraction theory
Authors: Harvey James E.
Published: March 2005

A general treatment of scaler diffraction theory is presented and some interesting concepts are discussed which yield new insight into the phenomena of diffraction throughout the whole space in which it occurs. The direct application of Fourier transform theory to the diffraction process results in two equivalent descriptions of the diffracted wave field: one describes the wave field as a superposition of plane-wave components and corresponds to the transfer function approach in linear systems theory, and the other describes the wave field as a superposition of hemispherical-wave components (or Huygen wavelets) and corresponds to the impulse response approach in linear systems theory. The convolution of the initial disturbance with the impulse response results in the well-known Rayleigh-Sommerfeld formula for near-field diffraction. This formula is then rewritten in the form of the Fourier transform integral of a generalized pupil function which includes phase variations in the diffracting aperture. Any departures of the actual diffracted wave field from that predicted by the Fourier transform of the aperture function are shown to have the same functional form as the conventional wave-front aberrations of imaging systems. These aberrations are precisely the effects ignored when making the usual Fresnel and Fraunhofer approximations.
James Clerk Maxwell’s inaugural lecture at King’s College London
Authors: Maxwell James C.
Published: March 2005

In this inaugural lecture given at King’s College London in 1871, James Clerk Maxwell (1831–79) reviews the current state of Natural Philosophy (Mechanics and Physics) and lays the foundation for the development of electromagnetic field theory.(AIP)
Event as the key to a graphic understanding of special relativity
Authors: Boas Mary L.
Published: March 2005

This paper discusses a method found useful in a relativity course for nonscience majors emphasizing logical reasoning rather than memory of facts. At the point where the Lorentz transformation might be discussed, we instead sketch diagrams of the two systems ’’according to S at time t,’’ and ’’according to S′ at time t′.’’ Each pair of sketches is related by one common event. Several specific examples illustrate the method.
Integral equations and scattering solutions for a square-well potential
Authors: Bagchi B. , Seyler R. G.
Published: March 2005

s-wave scattering solutions of the Schrödinger equation with an arbitrary central local potential are considered. Green’s functions and integral equations are derived for scattering solutions subject to a variety of boundary conditions. Exact solutions are obtained for the case of a finite spherical square-well potential, and properties of these solutions are discussed.
Resource Letter PhD-1: Physics demonstrations
Authors: Davis John A. , Eaton Bruce G.
Published: March 2005

This Resource Letter has been prepared as a project of the AAPT Committee on Apparatus for Educational Institutions. It represents a response to questions raised at the 1978 winter meeting in San Francisco concerning sources of information on lecture demonstrations. Thus, this letter is aimed more at readers who have recently become interested in lecture demonstrations, rather than those who are already familiar with the literature. While the authors have examined a great deal of material, and have had help from many people, there are always materials which have been overlooked. Therefore, we earnestly request that any reader with suggestions or corrections please communicate with the authors so that they may be included in any future updating. Because of the introductory scope of this Resource Letter, we have not included all of the resources that are available. Most foreign works, books known to be out of print, items having small circulation, and textbooks and earlier editions bearing differing titles have been excluded. The reader may refer to the annotated bibliography by John A. Davis (Sec. I B5) for a more extensive listing of the literature. When possible, the annotations are followed by one or more reviews so that other opinions can be consulted.
Can a body pass a body falling through the air?
Authors: Coulter Byron L. , Adler Carl G.
Published: March 2005

Galileo reported that if two balls with different densities are dropped simultaneously, the less dense ball will initially fall faster, but later lag behind the more dense ball. The authors observed this same behavior for a lead ball and a billiard ball of different size. Numerical calculations show that due to the complex dependence of the drag coefficient on the velocity and size of a ball, it is possible under certain coditions to drop two balls simultaneously and find that one initially lags behind but then passes the other. However, the specific behavior observed by the authors, and probably Galileo also, was most likely due to a systematic error in the dropping apparatus.
Asymptotic freedom made simple
Authors: Ma Ernest
Published: March 2005

The notion of asymptotic freedom in quantum chromodynamics is ’’explained’’ on general physical grounds, without invoking the formal arguments of renormalizable quantum field theory. The related concept of quark confinement is also discussed along the same line.
Effect of weight transfer on a vehicle’s stopping distance
Authors: Whitmire Daniel P. , Alleman Timothy J.
Published: March 2005

As a braking vehicle decelerates, friction forces between the tires and road produce a torque about the vehicle’s center of mass. This effect, called weight transfer, removes weight from the rear wheels and results in a minimum stopping distance that is in general longer than that given in the usual textbook treatment. In this paper we present an analysis of the minimum stopping distance problem taking into account the effect of weight transfer on (i) nonskidding vehicles and (ii) front- or rear-wheels-skidding vehicles. Expressions for the minimum stopping distances are given for both cases in terms of vehicle geometry and the coefficients of friction. In the case of nonskidding stops we obtain an expression for the optimum brake ratio which will allow all wheels to simultaneously brake at the point of incipient skid. Under this condition a minimum ’’textbook’’ stop is achievable in principle, but only on a given road surface. These results are found to be in qualitative agreement with measured stopping distance data.
Use of physical analogs to evaluate infinite series
Authors: Epstein D. J. , Smith A. C.
Published: March 2005

We consider two physical examples that lead to infinite series: (i) the Madelung energy of a one-dimensional array of alternating positive and negative charges and (ii) a point charge between infinite parallel plates. The series for the first example is conditionally convergent, and therefore, the sum is dependent upon term ordering. However, for each arrangement there exists a specific physical analog. The series of infinite images arising in the second example is divergent. Here, the physical analog is not helpful in evaluating the sum. We point out that failure of the analog is tied to certain historical difficulties encountered in the development of the theory of divergent series.
Einstein and general relativity: Historical perspectives
Authors: Chandrasekhar S.
Published: March 2005

E d i t o r’s Note: This paper was presented as the 1978 Oppenheimer Memorial Lecture at Los Alamos Scientific Laboratories on August 17,1978.
Laboratory study of airborne fallout particles and their time distribution
Authors: Smith H. A. , Ward T. E. , Hicks K. H. , Nelson C. J.
Published: March 2005

Simple γ-ray detection and analysis techniques were utilized to study the radioactivity in samples of filtered airborne particulate, collected daily for approximately the first month after the 18 September 1977 Chinese nuclear detonation. Fourteen fission products were detected in the filter samples which contained radioactive fallout, and fluctuations in the daily fallout activity levels suggested a global fallout orbit time of approximately 20 days.
Monte Carlo demonstration of solid-state diffusion in an electric field
Authors: Murch G. E.
Published: March 2005

We describe the phenomenological and microscopic aspects of solid-state diffusion in an electric field. We then present a Monte Carlo method which is used to simulate an atomistic model of diffusion in an electric field. The Nernst-Einstein relation, which relates the drift mobility and the diffusivity, is then discussed and verified with results of the computer calculation.
The Slinky as a model for transverse waves in a tenuous plasma
Authors: Blake Julian , Smith L. N.
Published: March 2005

Transverse waves in a Slinky suspended by an array of strings share the dispersion relation for transverse electromagnetic waves in a tenuous plasma. Experimental results for the Slinky system are presented, suggesting a useful and simple laboratory exercise for an elementary physics course.
Two-dimensional appearance of a relativistic cube
Authors: Hickey F. R.
Published: March 2005

The two-dimensional or ’’photographic’’ appearance of a cube moving at relativistic speeds is investigated. It is shown that the appearance of the cube depends upon whether the camera is held fixed with the optic axis perpendicular to the direction of motion or panned to follow the cube as it moves. The Lorentz contraction, as it is usually defined, is not visible in either case. However, if the camera is rotated, the photographic appearance has some of the characteristics of a picture of a stationary rotated cube.
Astronomical meaning of a tropical year
Authors: Benumof Reuben
Published: March 2005

A tropical year is usually described incorrectly as the actual interval between two successive passages of the Sun through the vernal equinox. These intervals vary from year to year because of the differing periods of the perturbations of the angular velocity of the Earth. A tropical year is correctly defined as the mean interval between two successive passages of the Sun through the mean equinox of date. The time of beginning of spring depends on (i) the perturbations of the angular velocity of the Earth, (ii) the nutation of the Earth’s axis, and (iii) the aberration of light.