bluuebunny/crossref_metadata_2025 huggingface dataset:
New Look at von Neumann's Operator Method in Quantum Statistics. I
Authors: Band William
Published: August 2005

This paper attempts to explain both the basic concepts and the mathematical formalism of von Neumann's operator method in quantum statistics, in terms that should be understandable by anyone who has mastered first courses in quantum mechanics and statistical mechanics. A simple model is used throughout the paper to illustrate the various theorems and techniques. The discussion begins with the statistical interpretation of the Heisenberg uncertainty principle, the definition of mixed ensembles, and the meaning of measurement in quantum mechanics. The von Neumann projection operator is explained, and is used to set up the ensemble density matrix and the von Neumann entropy operator.

In the second part of the paper, to be published later, the quantum-mechanical equation of change with time is applied to the von Neumann operators.
Moments of Inertia of Plane Triangles
Authors: Satterly John
Published: August 2005

The moments of inertia of the triangle are calculated about various axes by direct geometrical methods and confirmed by experiment.
Some Considerations about the Precision of the International Standard of Wavelength
Authors: Ch'en Shang Yi
Published: August 2005

The precision of the accepted value for the wavelength of the red line of Cd is discussed. The uncertainty due to the setting of the end marks by a microscope in interferometric measurements, the correction for the refractive index of air, and the difficulty in controlling precisely the conditions of excitation of the light source are reviewed with considerations for a new standard of wavelength and a new pair of end marks.
Writing Test Exercises in the Natural Sciences
Authors: Nedelsky Leo
Published: August 2005

This paper is concerned with general principles to be used in writing test exercises, especially objective test exercises, in natural sciences. Most examples will be drawn from physics, the field in which the author feels most at home; the generalizations which these examples are to illustrate, however, should be applicable to any of the natural sciences.
Effects of Time-Varying Impulses on a Ballistic Galvanometer
Authors: Woodbridge David D. , Varner W. R.
Published: August 2005

A method was developed for obtaining traces of the motion of a ballistic galvanometer coil as a function of time. The traces show that the lag of the galvanometer coil depends on the impulse time. The study also shows the relationship between the impulse time and the maximum deflection of the galvanometer coil.
Correlation of High School and College Grades
Authors: Schoepfle G. K. , Arnold D. L.
Published: August 2005

Correlation of college grades with high school grades shows that a good grounding in mathematics is essential for success in college physics and that the Ohio State University Psychological Test and the complete high school grades provide good college guidance and planning. Beyond 5 basic courses in high school science, achievement, ability, and interest seem more important than more courses. It is hoped that attempts to interest more students in mathematics and physics will not attract students who lack the proper attitude.
Demonstration Experiments in Electrostatics
Authors: Ainslie D. S.
Published: August 2005

This paper outlines methods of producing positive electrification, for demonstrations in electrostatics, and modifications in the standard electrophorus suitable for use in humid weather. A short description is given of construction and action of an electrostatic machine with cylindrical elements and the use of a radiotron circuit to demonstrate the importance of shielding sensitive electrical equipment.
Design of Examinations and Interpretation of Grades
Authors: Strandberg M. W. P.
Published: August 2005

There are two inadequacies of usual teaching methods about which something can be done. The design and evaluation of examinations, as popularly applied, are nonquantitative; and the average student is inadequately prepared for understanding the learning process. Three criteria are presented which may be of use in resolving these difficulties. These criteria are the concept of logical steps, the concept of avenues of approach, and the concept of the nature of examinations.
Sensitive Semiconductor-Detector for Infrared Radiation
Authors: Varićak M.
Published: August 2005

It is the purpose of this note to describe a simple thermistor-bolometer, suitable for demonstration experiments in infrared radiation and the radiation emissivity of various surfaces.
CO
2
Electrostatic Generator
Authors: Mascarenhas S. , Gambirasio F. , Mascarenhas Y.
Published: August 2005

Several interesting electrical effects observed with solid and gaseous CO2 are reported. An unusual electrostatic generator running at −78°C with dry ice is described. The generator, which can be easily constructed, is capable of giving a 8 μamp short-circuit current and enough voltage (from 15 to 20 kv) for the performance of all common electrostatic demonstrations. Quantitative data about the generator are also given. A discussion of the basic charge-separating mechanism is given, supported by a series of simple experiments. These results indicate that charge separation takes place in the nozzle of the gas cylinder, probably owing to friction of the escaping gas with the walls.
Useful Diagram
Authors: Freier George D.
Published: August 2005

The relations between many of the parameters in nuclear scattering problems are shown in a simple geometrical construction.
Steady-State Theory at Chicago
Authors: Schlegel Richard
Published: August 2005

In papers published in 1918 and 1925 W. D. MacMillan suggested that the universe maintains a steady state in its large-scale astronomical features, as a result of a balance between matter-to-energy conversion in stellar interiors and creation of atoms from radiant energy in empty space. No mechanism for the atom-creation process in space was suggested. R. A. Millikan used the MacMillan theory as a basis for a theory of the origin of cosmic rays, but in a few years' time accumulating evidence made that theory untenable, and interest in the MacMillan theory then also dropped. Similarities between the MacMillan and Bondi-Gold-Hoyle steady-state theories are noted.
Graphical Analysis of the Moment of Inertia Experiment
Authors: Van Name F. W.
Published: August 2005

A graphical method for eliminating the effect of friction in the moment of inertia experiment is described. A typical set of data is presented. The improvement in accuracy obtained by this method is shown, as compared to the value obtained when friction is neglected.
Elementary Experiment in Deriving an Empirical Relationship
Authors: Worrell Francis T. , Correll Malcolm
Published: August 2005

The experiment described in this paper is intended to illustrate to the student the process of empirical formulation, which is an important step in the development of a physical theory. The physical system used is a bar pendulum pivoted at its upper end. Bars of various lengths are available for a study of the effect of length on period. The results are plotted in various ways, and the law of the system determined.
A Few More Words about Units
Authors: Mooney Robert L.
Published: August 2005

The importance of presenting the subject of units and dimensions in a clear and rigorous fashion is herein re-emphasized in an informal manner in the hope that the comments and observations of the author will be considered further by conscientious teachers of physics in secondary schools and in colleges.
Copenhagen Interpretation of Quantum Theory
Authors: Hanson Norwood Russell
Published: August 2005

The theoretical and experimental context within which the “Copenhagen Interpretation” of quantum theory was generated is underemphasized by recent critics of the Bohr-Heisenberg philosophy. When an interpretation of a theory has been as successful as this one has been, there is little practical warrant for the “alternative interpretations” which have, since Bohm, been receiving prominence. Indeed, these are not even genuine alternatives; although rich in provocative prose, they provide not a scrap of algebra with which to organize the practical physicist's thinking. Several objections to the Bohr interpretation are critically examined, as is also a particular use of the correspondence principle which has seemed to cast doubt on the Copenhagen ideas.
Electromagnetic Equations Written in a Form Independent of the System of Units
Authors: Berreman Dwight W.
Published: August 2005

This paper illustrates a form for writing electromagnetic equations such that by substituting the appropriate value for each of two arbitrary constants one immediately obtains the electromagnetic equations written in any of the consistent systems of units. One constant is a dimensionless term called a rationalizing factor that takes the value 4π in unrationalized systems and unity in rationalized systems. The other is ε0, the capacitivity of free space. Except for the rationalizing factor, all equations are identical in appearance with equations written in the rationalized MKSQ system of units. Maxwell's equations and some other commonly used relations are presented in this form. A simple method of obtaining the equations in the Gaussian and the Heaviside-Lorentz mixed systems of units from the form presented for consistent systems is also given.
Some Experimental Aspects of Superconductivity
Authors: Boorse Henry A.
Published: August 2005

This paper is the substance of an address delivered at the annual meeting of AAPT in New York on January 31, 1958.
Radio Tracking of Earth Satellites
Authors: Moorcroft D. R.
Published: August 2005

The characteristics of artificial earth satellite orbits are summarized and related to an observer on the surface of the earth. Equations and analytical approaches are developed for determining the orbit of a transmitting satellite using information from equipment for measuring the Doppler shift of the transmitted signal. These are extended to include observations with an array of interferometers (several different arrangements are considered).
Theoretical Calculations and Experimental Verification for a Demonstration Thermal Diffusion Column
Authors: Español Carlos E. , Carjuzaa Carlos R.
Published: August 2005

The present paper exemplifies the theoretical calculations for a thermal diffusion column of the hot filament type, easy to build in college laboratories. The separation of a binary mixture of carbon dioxide and argon has been studied and the separation factor, theoretically calculated, has been checked against the experimental separation factor. The results show an acceptable agreement.
Plug-in Basic Physics Course
Authors: Hefferlin Ray
Published: August 2005

An extension of Eric Rogers' “block-and-gap” basic physics outline is proposed to include interchangeable blocks. Typical “plug-in units” and combinations of units are listed, and the coverage of essential material is discussed.
Measuring Artificial Star Separation by Interference
Authors: Pryor Marvin J.
Published: August 2005

Star diameters were originally measured by the Michelson stellar interferometer by varying the separation of mirrors of small aperture which were mounted on a twenty-foot beam. The model here described enables students to obtain values for the separation of artificial stars by interference which are as accurate as measurements obtained by a vernier caliper. It demonstrates a series of diffraction and interference phenomena.
On the Analogy between Dynamics and a Game of Cards
Authors: Heerden P. J. van
Published: August 2005

It is shown that there is an analogy between dynamics and a simple game of cards. The dynamical quantities like velocity, mass, momentum, and kinetic and potential energy find their equivalents in the card game.
Height of Fall Versus Frequency in Liquid Rope-Coil Effect
Authors: Barnes George , Mackenzie James
Published: August 2005

When height of fall is plotted against frequency of coiling in the liquid rope-coil experiment a straight line relationship that does not pass through the origin results. A correction due to the effect of surface tension on the stream of falling liquid yields “effective” heights of fall which, when plotted against the rate of coiling, does result in a straight line through the origin.
Satellite Paradox
Authors: Mills Blake D.
Published: August 2005

As an artificial satellite gradually descends in a near-circular orbit, its linear velocity increases. Its acceleration in the direction of its motion is found to be the same as if the air drag force, reversed, were pushing the satellite.
Simple Schrödinger Wave Functions which Simulate Classical Radiating Systems
Authors: Dean C.
Published: August 2005

A type of solution of the time-dependent Schrödinger equation is suggested which intuitively corresponds to the system being midway through a radiative transition. This type of solution gives probability amplitudes and certain expectation values which oscillate in time. Some features of these oscillations closely resemble the comparable classical radiating system, and this correspondence seems useful in teaching the introductory quantum-mechanical theory of radiation.
A Step Away from the Conventional Laboratory in Introductory Physics
Authors: Laster Howard
Published: August 2005

A compromise between the extremes of the free laboratory and the conventional laboratory is described. A major feature of this compromise is the requirement that students present two long laboratory reports each semester, in addition to doing a more conventional series of short experiments. Even in the short experiments, students are encouraged to use their own methods of approach to the prescribed topics. The student and faculty response is described. The results justify further exploration along the same lines.
Demonstration of Magnetic Domains
Authors: Dillon J. F. , Earl H. E.
Published: August 2005

The advent of transparent ferrimagnetic materials has made possible the direct observation of magnetic domains with a polarizing microscope. A description is given of a simple self-contained polarizing microscope suitable for demonstrating the behavior of domains. The procurement of crystals and the actual specimen preparation are discussed. With this demonstration one can observe many of the properties of magnetic domains; the influence of external fields, of changes in the magnetization, and the influence of imperfections on domain structure, to name a few. The authors suggest that the use of such a demonstration microscope as an instructional aid should facilitate greatly the teaching of magnetism on a relatively fundamental plane.
Numerical Integration Applied to the Galvanometer Equation
Authors: Woodbridge David D.
Published: August 2005

An exact solution of the ballistic galvanometer equation, without any assumptions, has been impossible until the development of numerical analysis methods. A set of predictor and corrector equations have been developed so that the theoretical motion of the galvanometer coil can be calculated for any type or combination of impulses. The galvanometer equation has been solved, for the Leeds & Northrup, 16-second period, ballistic galvanometer. The equation was solved for sine wave, capacitor discharge, square wave, and double sine-wave impulses.
Equivalence of Huygens' Principle and Fermat's Principle in Ray Geometry
Authors: de Witte A. J.
Published: August 2005

Rays determined by Huygens' construction are identical with those derived from Fermat's principle. This is shown to be true whatever the medium or sequence of media traversed by the rays.
Systematic Approach to the Calculation of Thermodynamic Transforms
Authors: Carroll Charles W.
Published: August 2005

In thermodynamics, transformation of intangible partial derivatives (for single-phase, constant-mass systems) into an experimentally measurable or easily calculable form is often necessary. Appropriate transformations may be systematically and efficiently derived by employing a minimum of basic thermodynamic concepts and applying selected mathematical techniques (including a limited use of Jacobians). It is hoped that the particular approach suggested will help students avoid gross memorization and artificial mnemonic or tabular schemes. In so doing, greater familiarity should be developed with the thermodynamic and mathematical interrelationships involved.
Epicyclic Orbits of Charged Particles
Authors: Harrison E. R.
Published: August 2005

In a uniform magnetic field and a central force of the form F = ξr, where ξ is a constant, charged particles describe epicyclic orbits in a plane perpendicular to the magnetic field for a limited range of ξ. These orbits are more varied than the simple trochoid which occurs when F is uniform. The orbits are of two kinds: the direct epicyclics and the retrograde epicyclics, corresponding, respectively, to motion occurring in central repulsion and central attraction force fields.
Eötvös Balance
Authors: Kolossvary Bela G.
Published: August 2005

Appreciation of potential, equipotential surfaces, and related concepts is more readily obtained on college level through the discussion of the theory and operation of the Eötvös balance. Description of the different kinds of balances suitable for various gravity measurements, the physical interpretation and measurement of the second partial derivatives of the potential function, as well as some experiments for advanced college students, are discussed.
Alternate Proof of the Existence of the Entropy Function
Authors: Evett Arthur A.
Published: August 2005

A proof is presented for the exactness of dQ/T based on showing directly that the reciprocity conditions are satisfied if one assumes the validity of Carnot's theorems.
New Look at the Theory of Electron-Phonon Resonance. I
Authors: Band William
Published: August 2005

In order to give a clear physical picture of the meaning of electron-phonon resonance, this paper develops the quantum mechanics of an electron in a linear lattice capable of longitudinal vibrations. In a second paper the results will be applied to illustrate the basic ideas of the theory of electrical conductivity.
Constant Current Supply for the Potentiometer
Authors: Watson E. E.
Published: August 2005

The emf of an ordinary lead acid storage cell is dependent on the currents that have been drawn from the cell during the preceding hours. A circuit, using two dry cells and a storage cell, which will maintain a current through a potentiometer constant to better than 0.001% for periods of at least ten minutes, is described. A similar arrangement will provide constant current through two resistances which are to be compared by the potentiometer method.
Classroom Models of Particle Systems
Authors: Eaton J. R.
Published: August 2005

The classroom models described provide means for illustrating many of the important behavior characteristics of the particles which form nuclei, atoms, molecules, gases, and crystals. The particles are represented by magnets which collide only through the interaction of field forces, and which move about with very little loss of energy. As a consequence, the behavior of a system may be observed through many particle collisions with but little attenuation in the system energy. The model is effective in demonstrating such behavior as the movement of electrons in the atom, the random motion of gas molecules, the thermalizing of neutrons, and the movement of electrons in crystals. Although the demonstration is restricted to classical behavior, it aids in the presentation of the quantum nature of matter.
Science in Elementary Schools
Authors: Navarra John Gabriel
Published: August 2005

Science has moved to a place of pre-eminence in the elementary school curriculum because of an emerging commitment that “learning is thinking.” The effectiveness of a program is related directly to how clearly the objectives for which it is operated are understood and how realistically the objectives are implemented.
Structure of Nonuniform Liquids
Authors: Cole G. H. A.
Published: August 2005

In an earlier paper in this Journal the modern arguments which lead to an understanding of a simple classical liquid under uniform conditions were considered. The more general case of nonuniform liquids is treated in the present paper and the methods currently used to determine the physical structure under these conditions are explained.
Maser States in Ammonia—Inversion
Authors: Vuylsteke Arthur A.
Published: August 2005

The purpose of the paper is to discuss the inversion effect in ammonia in terms of a simple square-well approximation to the potential. This effect is of some present interest since two so-called inversion states have recently been used to achieve maser action in ammonia. A brief discussion of general mechanical features of the ammonia molecule and a semiclassical derivation of the rotational energy spectrum is followed by a discussion of inversion doubling in the vibrational spectrum and a brief treatment of the internal dynamics of the molecule. This is followed by a discussion of the Stark effect on the inversion doublets. The paper is then concluded with a brief description of the principle of the ammonia beam maser.
Institutional Influences in the Undergraduate Training of Ph.D. Physicists
Authors: Siebring B. Richard , Schwahn Duane H.
Published: August 2005

Institutions of the United States are ranked by the ratio of Ph.D.'s in physics granted nationally during 1952 to 1956 to their undergraduate physics majors who received their bachelor's degrees during the period July 1, 1947, to June 30, 1952, as a means of measuring their efficiency in the training of Ph.D. physicists. The data used in calculating these ratios were obtained from the National Academy of Sciences and the United States Office of Education. The top ten institutions were found to be Hampden-Sydney College, Swarthmore College, University of Colorado, Haverford College, Drew University, Wesleyan University, University of Virginia, Johns Hopkins University, Whitman College, and Cornell University, in that order.

As a means of comparing various groups of institutions, composite Ph.D.-bachelor ratios were calculated. From these ratios certain conclusions were drawn. This investigation differed from most other studies of this sort, for in it the Northeastern states were found to be the most productive. The technical schools surpassed the universities and colleges. It was found that the Ph.D. granting institutions had a much higher composite Ph.D.-bachelor ratio than the institutions not offering doctoral work in physics.
Projections of Dipole Flux Patterns
Authors: Correll Malcolm
Published: August 2005

A method of making projections of three-dimensional flux patterns is described. The resulting figures are shown for cases where the dipole axis and the picture plane make angles of from 0° to 70° in steps of 10°.
Effect of Spin and Speed on the Lateral Deflection (Curve) of a Baseball; and the Magnus Effect for Smooth Spheres
Authors: Briggs Lyman J.
Published: August 2005

The effect of spin and speed on the lateral deflection (curve) of a baseball has been measured by dropping the ball while spinning about a vertical axis through the horizontal wind stream of a 6-ft tunnel. For speeds up to 150 ft/sec and spins up to 1800 rpm, the lateral deflection was found to be proportional to the spin and to the square of the wind speed. When applied to a pitched ball in play, the maximum expected curvature ranges from 10 to 17 in., depending on the spin. The deflections of rough baseballs accord in direction with that predicted by the Magnus effect. But with smooth balls at low speeds the deflection is in the opposite direction. This is studied with an apparatus specially designed to measure the pressure at any point in the equatorial plane of the rotating ball.
On Accidental Degeneracy in Classical and Quantum Mechanics
Authors: McIntosh Harold V.
Published: August 2005

The theory of accidental degeneracy is surveyed, particular attention being paid to the connection between the accidental degeneracy of the two-dimensional isotropic harmonic oscillator and the theory of angular momentum.
Evaluation of High School Physics Courses by College Students
Authors: Kruglak Haym
Published: August 2005

Physics students at Western Michigan University rated their high school physics course and instructor. The data were used to identify the outstanding instructors of the area and to reveal their methods. There was a strong relationship between the ratings of the instructors and the ratings of the high school physics course as a preparation for college science courses. There was a significant difference in the general college physics grade distributions of students with and without high school physics.
Improvement to the Franck-Hertz Experiment
Authors: Dewdney John W.
Published: August 2005

Bernheim, Gossard, and Pound have devised a modification of the Franck-Hertz experiment in which the traditional peaks are displayed on an oscilloscope. Minor sophistications in their method make possible the display of 25 or more maxima.
One-Dimensional Hydrogen Atom
Authors: Loudon Rodney
Published: August 2005

The quantum-mechanical system which consists of a particle in one dimension subjected to a Coulomb attraction (the one-dimensional hydrogen atom) is shown to have a ground state of infinite binding energy, all the excited bound states of the system having a twofold degeneracy. The breakdown of the theorem that a one-dimensional system cannot have degeneracy is examined. The treatment illustrates a number of properties common to the quantum mechanics of one-dimensional systems.
Historical Survey of the Early Development of the Infrared Spectral Region
Authors: Barr E. Scott
Published: August 2005

This account of the early history of the infrared spectral region is concerned with tracing the growth in understanding of the nature and properties of this radiation from the time of its discovery by Herschel in 1800 up to the first part of the present century. After workers in the first half of the 19th century had demonstrated the fundamental similarity of infrared and visible radiation, investigators during the second half discovered the materials and evolved the techniques of measurement and control of infrared radiation which provide the foundation for the current extensive use of infrared equipment in research, industry, and ordnance.
The Case of the Counting Balls
Authors: Kline John V.
Published: August 2005

The mysterious demonstration experiment involving a linear array of elastic spheres is discussed. An approach is suggested which permits a sophomore to compute a predicted result, both for the simple case where masses are equal and the number of emerging balls is equal to the number of incident balls, and for the more complicated case of unequal masses where the balls do not know how to count.
Some Exact Solutions of the Time-Dependent Schroedinger Equation
Authors: Myers Vernon W.
Published: August 2005

Exact solutions of the time-dependent wave equation are given for the one-dimensional motion of a particle acted on by an external force and for a forced oscillator. The solutions chosen correspond to the same time dependence for the classical momentum and for the quantum-mechanical space average of the momentum.
Simple Derivation of the Clebsch-Gordan Coefficients
Authors: Sharp R. T.
Published: August 2005

The three-dimensional angular momentum operator J takes a simple form when the operand is a scalar function f(ξ,η) of the two complex variables ξ, η; so do the angular momentum eigen-states fmi(ξ,η). Exploitation of this circumstance leads to a simple derivation of Racah's formula for the Clebsch-Gordan (vector addition) coefficients.
On the Validity of Kirchhoff's Law for a Freely Radiating Body
Authors: Weinstein M. A.
Published: August 2005

In applying Kirchhoff's law to calculate the emission of a heated body radiating freely to the outside, one assumes that the emission of a body when radiating freely is the same as its emission when enclosed in a blackbody cavity. But the radiation field inside the body is everywhere smaller in the first case than in the second; consequently the emission arising from induced radiative transitions must be smaller for a freely radiating body than the emission arising from these transitions when the body is enclosed in a cavity. Since the emissions differ, one is apparently led to the conclusion that Kirchhoff's law cannot be valid for a freely radiating body. It is shown that this conclusion is false: Kirchhoff's law is valid as long as the distribution over material states is the equilibrium distribution, and is therefore, in this sense, independent of the state of the radiation field. One must, however, take proper account of the effect of induced emission in calculating the absorption coefficient.
Derivation of the Speed of Electromagnetic Waves in Terms of Dielectric Constant, Magnetic Permeability, and Ratio of Charge Units
Authors: Werner Frederick G. , Brill Dieter R.
Published: August 2005

We give an elementary derivation of the expression for the propagation speed of a change in the electromagnetic field in terms of the dielectric constant, the magnetic permeability, and the ratio of magnetic to static units of charge. The only knowledge of electrodynamics required is familiarity with the expressions for the electrostatic charge on a parallel plate condenser, the magnetic field in a long solenoid, and the induced emf in a loop. Also easily found are expressions for the characteristic impedance of the medium (or the vacuum) and displacement current. These are introduced in a rather directly conceivable physical manner. No use is made of calculus or vector analysis proper. No swiftly moving bodies are considered. Units are kept general so that reduction to any particular unit system is easy.
Role of Physics in Revision of Engineering Curricula
Authors: Parsegian V. L.
Published: August 2005

It has been said that engineering education has been overspecialized, compartmentalized, and insufficiently founded on fundamentals, not only with respect to engineering courses but equally in the basic science courses. Improvements are being attempted through reorganization and integration of engineering science materials, given as common courses in categories such as thermodynamics, fluid mechanics, materials and solid state, etc.

Science courses must also eliminate compartmental thinking. Students need more than the elements and concepts of basic science in a limited frame of reference; they must achieve quantitative understanding of the interrelationship and underlying unity of the laws of nature, through a wide range of natural phenomena. Transition and translation from micro to engineering macro realms, from physical to chemical to biological phenomena, must be made meaningful in a quantitative sense.

The role of physics is not to teach engineering mechanics or electrical circuitry, but the phenomena that underlie and introduce these effectively. There is particular need to stress and to take examples from atomic systems as far as possible, even with freshman physics.
Apparatus Drawings Project. Report Number 3. Air Suspension Gyroscope
Authors: Marcley Robert G.
Published: August 2005

The apparatus to be described will permit the quantitative study of gyroscopic precession in an undergraduate laboratory. By suspending a rotating, magnetized, steel sphere on a jet of air and driving it as a synchronous motor by means of a rotating magnetic field, it is possible to eliminate, for all practical purposes, corrections for frictional losses in gimbal bearings. By using only a stop watch, micrometer caliper, and a simple stroboscope, an experimental error of 0.5% may be easily obtained. By suitable refinement of the equipment and techniques, an experimental error of 0.01% may be achieved.
Energy Loss from the Filament of an Incandescent Lamp
Authors: Dewdney John W.
Published: August 2005

The current-voltage characteristic of a lightbulb can be analyzed graphically to reveal much about heat loss from a hot filament. The low-temperature region is particularly interesting. The experiment can be done and the effects understood by elementary students.
Nature of Physics and Its Relation to Other Disciplines
Authors: Thomson George P.
Published: August 2005

Physics is one aspect of the science which deals with nonliving matter. It is concerned primarily with general principles valid either for all kinds of material, as for example gravitation, or relating to laws in which matter as such does not come in directly ; for example, the propogation of electromagnetic waves in a vacuum. However, the boundary between physics and chemistry in common parlance is largely historical in origin.

Physics is a great triumph of the human mind, but it has often grown from the study of apparent trivialities. That these can lead to the most important discoveries is itself one of the great discoveries of the scientific method. There is as yet no all-embracing physical theory, and as knowledge increases the significance of the partial theories is seen to change, but they are seldom entirely superseded. Even a successful universal theory would leave much to do; the consequences of theories are deemed worthy or unworthy of study for aesthetic or practical reasons.

Nature is no longer considered to be deterministic in detail though it is in gross.

The practical value of physics showed itself clearly in the development of electrical engineering, and now physics has become essential to a developing civilization.

Scientists are responsible for those consequences of their actions which reasonably can be foreseen, but the extent to which consequences can be foreseen is exaggerated. The different parts of a civilization are interlocked and it must be accepted or rejected as a whole.
Elementary-Particle Physics
Authors: Burkhardt Hugh
Published: August 2005

In Sec. A, a review is given of the modification of the classical picture of forces and particles by the ideas of quantum theory leading to Yukawa's meson hypothesis. In Sec. B, some aspects of the present knowledge of the elementary particles and their interactions are discussed from a phenomenological point of view.
Cosmic Radiation
Authors: Scarsi Livio
Published: August 2005

The paper gives some general information about cosmic rays, especially with regard to the properties of the primary flux: charge composition, energy spectrum, and time variations. The experimental evidence for these properties of the cosmic rays is outlined briefly and possible origins of the radiation are discussed.
Metallurgy in the Development of Atomic Power
Authors: Sabato J. A.
Published: August 2005

Some of the metallurgical problems in the construction of nuclear reactors are discussed. Typical problems resulting from neutron bombardment encountered such as uranium growth, deterioration of fuel cans, thermal effects, and radiation effects, are presented in detail. Solutions to some of these problems found during the construction of the Calder Hall reactor in the United Kingdom are given as examples of the complex problems encountered. Some of the basic solid-state effects due to neutron irradiation are still not fully understood and are being investigated.
Introduction to Soft X-Ray Spectroscopy
Authors: Pike E. R.
Published: August 2005

The presentation of some fundamental ideas concerning the behavior of electrons in solids is followed by an outline of the theory of the use of x-ray methods for obtaining information about these electrons. Experimental methods are discussed briefly and some recent trends and developments in the subject are reviewed.
Is There an Ideal Crystal?
Authors: Dobbs E. Roland
Published: August 2005

An elementary classification of crystals according to their binding forces shows that an ideal crystal, defined as a perfect lattice of spherical atoms held together with two-body, central forces, should be found among the inert gas solids. The calculation of a lattice energy from an interatomic potential of the Mie-Lennard-Jones form is discussed, and the results for the hexagonal and cubic close-packed lattices compared. For argon, it is shown that a (12,6) interatomic potential, whose constants have been calculated from the crystal parameters at 0°K, can be used to predict both the specific heat of the crystal and the second virial co-efficient of the gas over suitable ranges of temperature. A comparison of this interatomic potential with existing calculations of the interaction of two argon atoms shows that the macroscopic properties of argon can be calculated at present from a pair potential, but not directly from the properties of an argon atom.
Paramagnetic Resonance
Authors: Kamper R. A.
Published: August 2005

The basic idea of paramagnetic resonance is presented in terms of a simple classical mechanical model. The model is then elaborated to show how paramagnetic resonance may be used to obtain information about atomic nuclei and the structure of crystals. A typical apparatus with which it may be observed is briefly sketched.
Graphical Derivation of the Inverse-Square Law of Gravitation from an Elliptic Orbit and Kepler's Law of Areas
Authors: Baez Albert V.
Published: August 2005

Motivated by the common knowledge that earth satellites move in elliptic paths, a graphical demonstration is presented which shows that if a small mass moves in an elliptic orbit about a large mass at one focus and obeys Kepler's law of areas, the force of attraction on it must vary inversely as the square of the distance between the two masses. The demonstration differs from the usual elementary proofs of the inverse-square law in that it assumes elliptic rather than circular orbits, uses the law of areas instead of the dependence of period on semimajor axis, and requires a minimum of formal mathematics. By using a similar construction it may be shown that if the large mass is at the center of the ellipse, the force varies linearly with distance.
Apparatus Drawings Project. Report Number 4. Air Suspension Apparatus for Measuring the Resolution of Forces
Authors: Marcley Robert G.
Published: August 2005

The equipment to be described is a sailboat model designed for use in an undergraduate student laboratory for the quantitative investigation of the resolution of forces The “sailboat” floats on a cushion of air to reduce friction to a minimum. The force to be resolved, which may be applied from any horizontal direction, is the “wind,” supplied by a high-velocity blower. The experimental error is less than 5%.
Advanced Placement Program in Physics
Authors: Moore Kenneth H.
Published: August 2005

The background and growth of the Advanced Placement Program are discussed. Construction, form, and grading of the examination are described. Some indications of the validity of the examination and acceptance by the colleges are presented. A number of problems still to be solved are posed.
National Science Foundation Institutes
Authors: Haenisch Edward L.
Published: August 2005

The program of the National Science Foundation for the support of academic-year, summer, and in-service institutes is summarized and the place of physics in the various institutes is analyzed. Details are given as to dates at which proposals must be received, what type of financial help is available to institutions and to participating teachers, and as to the factors that all institutes have in common.
Secondary School Physics: The Physical Science Study Committee
Authors: Finlay Gilbert C.
Published: August 2005

The physics course developed by the Physical Science Study Committee is outlined in some detail. Examples of the laboratory work and of the instructional films that accompany the course are included to show how these parts of the course are integrated with the text on the one hand and supplementary to it on the other.
Course in Physics for Students of Architecture
Authors: Williamson Charles
Published: August 2005

This course was set up for freshmen in architecture whose preparation in science and mathematics may be limited and whose major interests are elsewhere. Because most of the mathematical difficulties in a course in elementary physics appear in mechanics and electricity, we begin with sound, light, and heat, postponing mechanics and electricity to the second semester. This unconventional order of presentation has the added advantage that our students find the subjects of sound, light, and heat unexpectedly interesting, and immediately applicable to problems confronting the architect. In this part of the course much of the laboratory work is descriptive and only semiquantitative. The textbook is supplemented with three specially written chapters dealing with the architectural applications of sound, light, and heat, and one more which summarizes the fundamentals of electricity. A reference shelf is set up.
On the Rationale of Lecture Demonstrations
Authors: Schilling Harold K.
Published: August 2005

Among the important, unique contributions lecture demonstrations can make to the effective teaching of physics are the following: 1. They confront the student with nature itself to an extent not possible in the laboratory. 2. They facilitate physical thinking. It is easier to theorize about a phenomenon after one has observed it directly. 3. For most students they provide unexcelled opportunities for observing, and thinking with, a physicist in action in a concrete problem situation. 4. They contribute to historical perspective and understanding, especially through the reenactment of classical observations or experiments, representing momentous discoveries.
Number of Images Produced by Multiple Reflection
Authors: Kulkarni V. M.
Published: August 2005

The number of images obtained by multiple reflection by two inclined plane mirrors is not, in general, independent of object position. Also, there is no single formula giving the number which holds good for every angle between the mirrors. One of the four rules laid down in this article can meet any general case with regard to the angle between mirrors or the object position.
Certain Matters in Relation to the Restricted Theory of Relativity, with Special Reference to the Clock Paradox and the Paradox of the Identical Twins. II. Discussion of the Problem of the Identical Twins
Authors: Swann W. F. G.
Published: August 2005

The problem of the “twins” concerns two twins a and b. With a at rest in S, we set b in motion, allow it to travel a certain distance, and then reverse the motion so that it returns to rejoin a. In this problem, acts are performed on b while nothing is done to a. The problem of the effects of imparting motion to an entity is analyzed in the light of the discussion in Part I, and the customary conclusion is established to the effect that, as measured by heartbeats, b ends the journey younger than a. The customary argument which produces the apparent paradox is to the effect that if we take our stand with b in S′, we see a moving away from b, then reversing its velocity with subsequent return to b, to find that it, a, is now younger than b. It is pointed out that in this second view of the problem there is danger of envisaging a situation entirely different from that of the first problem. The danger lies in supposing that in the frame which accompanies b something is done to a—in the reversal of its velocity. The second view of the matter should recognize that to secure the apparent reversal of velocity of a as seen by b, we should not do something to a from the frame of b, but should do something to b from the frame of b itself. If the discussion is carried out in this manner, no paradox results.
Well-Informed Heat Engine: Efficiency and Maximum Power
Authors: Finfgeld C. , Machlup S.
Published: August 2005

Further analysis is presented of a thought experiment due to Raymond, which permits an apparent violation of the second law of thermodynamics (the conversion of heat into work by a cyclic process), utilizing spontaneous fluctuations, and supplying the negentropy in the form of information obtained by counting. The thermodynamic efficiency of the heat engine itself is unity; considering the engine and counting demon together preserves the sanctity of the second law. An expression is derived for the power delivered by the engine, and the maximum value of this expression is studied as a function of the various parameters.
Momentum Space Representation and Photodisintegration of the Deuteron
Authors: Suh Kiu S.
Published: August 2005

The momentum space representation is discussed in general and an application is made, deriving the cross section of the photodisintegration of the deuteron, using the Hulthen wave function. The theoretical results are compared with the experimental values, and the Hulthen wave function parameter is determined.
Partition Function of an Atom in a Spherical Box
Authors: Mazo Robert M.
Published: August 2005

The density of states of spherical waves used in the calculation of low-temperature second virial coefficients of gases leads to an incorrect result when applied to the partition function of an ideal gas in a spherical box. A more accurate density of states is derived and shown to lead to the correct result. It is argued that the corrections play no role in the calculation of the second virial coefficient, and hence the known results for that case need no revision.
Similarity Solutions in Fluid-Gas Dynamics
Authors: Borg S. F.
Published: August 2005

Following a brief discussion of the general applicability of similarity transformations in solving fluid-gas dynamic problems, certain specific problems solved in this manner are described.
On Experimental Tests of the General Theory of Relativity
Authors: Schiff L. I.
Published: August 2005

This paper explores the extent to which the three “crucial tests” support the full structure of the general theory of relativity, and do not merely verify the equivalence principle and the special theory of relativity, which are well established by other experimental evidence. It is shown how the first-order changes in the periods of identically constructed clocks and the lengths of identically constructed measuring rods can be found without using general relativity, and how the red shift and the deflection of light can be computed from them. Only the planetary orbit precession provides a real test of general relativity. Terrestrial or satellite experiments that would go beyond supplying corroborative evidence for the equivalence principle and special relativity would be extremely difficult to perform, and would, for example, require a frequency standard with an accuracy somewhat better than one part in 1018.
Eötvös Experiment and the Gravitational Red Shift
Authors: Dicke R. H.
Published: August 2005

The relation of the results of the Eötvös experiment to the equivalence principle is discussed. It is asserted that the equivalence principle is not established by the results of the Eötvös experiment. The type of discrepancy discussed could result in an anomalous gravitational red shift. Consequently, contrary to the conclusion of L. Schiff's article [Am. J. Phys. 28, 340 (1960), this issue], red shift experiments are considered important.
An Unmixing Demonstration
Authors: Heller John P.
Published: August 2005

It is pointed out that the usual mathematical description of the slow flow of viscous liquids within rigid boundaries indicates that such motion is reversible in time. The equations of a mixing transformation, in the geometry of the Couette viscometer, are given. The motion is ideally quite reversible, but because the fluid consists of molecules subject to thermal agitation, the pattern is smeared out in time. Observed unmixing by reversal of motion, although striking, is not perfect.
The Fluid Column
Authors: Mills Blake D.
Published: August 2005

When a piece of metal tubing is filled with fluid under pressure, it has been found that the tube may buckle elastically by lateral deflection, before it either yields or bursts. Analysis and experiment show that the behavior is much like the buckling of an ordinary column subjected to axial compression