bluuebunny/crossref_metadata_2025 huggingface dataset:
Hall Effect and Ponderomotive Force in Simple Metals
Authors: Rostoker Norman
Published: August 2005

The Bloch-Sommerfeld theory of conductivity is applied to the calculation of momentum lost by conduction electrons because of collisions with the crystal lattice. The momentum lost by the conduction electrons, suitably averaged, is interpreted as a force per unit volume acting on the crystal lattice. The calculations provide the basis for a microscopic interpretation of the ponderomotive force f = (1/c)(j×H) per unit volume.

In the case of metals which conduct in a single band, the ponderomotive force f is produced entirely by the action of the Hall electric field on the crystal lattice. When conduction takes place in more than one band f is partially caused by the action of the Hall electric field on the crystal lattice and partially caused by collisions of conduction electrons with the lattice.
Particle Tracks in Nuclear Emulsions
Authors: Beiser Arthur
Published: August 2005

After a brief survey of the properties of nuclear emulsions, the production of tracks in them by ionizing particles is discussed. The various techniques in use for determining the charge, mass, and energy of the particles are reviewed, with the interpretation of grain density, track range, delta-rays, and multiple scattering measurements described. Lastly, consideration is given to auxiliary methods for neutron detection and the magnetic deflection of particles between emulsions.
The Peripheral Potential Drop of an EMF Inside A Conducting Medium
Authors: Gemant Andrew , Miller E. B.
Published: August 2005

When an emf, embedded in an electrically conducting medium, is measured by peripherally applied probe electrodes, the ratio of the measured potential drop to the total emf must be known. It is shown how this ratio can be obtained by computation. The specific case of an electromagnetic blood flow meter is used as the basis of computation.
A Problem in Heat Conduction and Its Solution
Authors: Rice David
Published: August 2005

This paper gives a mathematical solution of a standard problem in one-dimensional heat conduction. It is intended to clarify the steps involved in solving certain boundary-value problems. Fourier series and integrals are involved, and the use of the probability integral is necessary for the final solution. Graphs of the original and final conditions are drawn to scale.
The Significance of Complementarity for the Life Sciences
Authors: Pollard William G.
Published: August 2005

A suggestion of Bohr's to the effect that numerous situations exist among the life sciences and the social sciences which exhibit characteristics of complementarity strikingly parallel to those of quantum physics is developed further in this paper. The supposition is advanced that there may exist for biological systems inherent relations of indeterminacy between sets of observable properties of such systems analogous to the Heisenberg indeterminacy relations between canonically conjugate pairs of observables in quantum mechanics. The existence of such indeterminacies would be manifested, as it is in physical systems, in disturbances, uncontrollable in principle, produced when such systems interact with instruments and apparatus used to gain information about them. The fact that radical disturbances, whether incidental or inherent, accompany the process of observation in the life sciences is, of course, quite obvious. If a well-defined portion of such disturbances should turn out to be inherent, indeterminacy and probability would be introduced into biological phenomena as basic elements. Further progress in scientific explanation and synthesis of knowledge in these fields would then require a redefinition of the state of a biological system analogous to the necessity for using quantum ψ-functions for specifying the state of a physical system with the attendant possibility of wholly new insights, such as those in physics which ultimately depend on the symmetry properties of ψ-functions. This new, and presently unknown, scheme for specifying the state of biological systems would then presumably result in the typically complementary aspects of phenomena in these fields to which Bohr has called attention. A number of familiar examples of apparently complementary phenomena among the biological and social sciences are described, and the possibility that they may arise from inherent indeterminacies basic to the systems which exhibit these phenomena is considered. It is concluded that these considerations lead to the expectation that an approach along such lines in future investigations in the life sciences holds considerable promise, and that the physics teacher is in a unique position to assist in stimulating such an approach and in pointing out by analogy the means at each stage which are likely to prove best suited for carrying it through.
The Spinning Nucleus in a Magnetic Field: A Source of Classroom Problems
Authors: Archibald W. J.
Published: August 2005

The object of this paper is to call to the attention of those teaching quantum mechanics several of the problems arising from the behavior of nuclei possessing a magnetic moment in an external magnetic field. These problems are simple enough to serve as student exercises. They are presented both from the classical and quantum-mechanical points of view, and this is particularly instructive in connection with the problems considered because both techniques of calculation lead to the same answers, but the results in spite of formal similarity are to be interpreted quite differently. This provides the teacher with an excellent opportunity to discuss the conceptual differences of the old and new mechanics.
William Gilbert on the Rainbow
Authors: Boyer Carl B.
Published: August 2005

A qualitatively satisfactory explanation of the rainbow was given shortly before 1311 by Theodoric of Freiberg and Qutb al-dīn al-Shīrāzī, but this work had disappeared shortly before Gilbert was born. The quasi-Aristotelian theory which Gilbert espoused was akin to early medieval ideas according to which rays from the sun are tinged as they traverse a thin dewy vapor and then are reflected to the eye of an observer by a dark cloud or dense object. Gilbert had the happy thought that a spherical magnet might serve as a miniature earth, but he missed entirely the notion of a globe of water as a magnified raindrop. Unaware of the role of the spherical drops in the refraction of solar rays, the fuzzy speculations on the rainbow which Gilbert gave in De Mundo stand in marked contrast to the experimental philosophy which he advocated in De Magnete.
American Physicists and Their Graduate Degrees
Authors: Cooper John N.
Published: August 2005

There are some 4200 physicists listed in the 1949 edition of American Men of Science. Roughly three-fourths have a doctoral degree; only about eight percent have no graduate degree. The number of graduate degrees granted to this group by each of the major American graduate schools has been tabulated. More than 1800 of the 3000 doctoral degrees were awarded by thirteen leading institutions, each-of which granted over one hundred Ph.D. degrees. The University of Chicago has awarded the largest number, 230. After Chicago come Cornell, California (Berkeley), Michigan, California Institute of Technology, Johns Hopkins, Harvard, Massachusetts Institute of Technology, Columbia, Yale, Wisconsin, Princeton, and Illinois. Over sixty other North American schools and fifty European institutions have granted one or more of the Ph.D. degrees.

A survey of the doctorates awarded during successive five-year periods reveals significant changes in the order of productivity of institutions. Within the past decade many schools have expanded their graduate programs to the point at which they are making significant contributions in training at the doctoral level.
A Demonstration of the Transformation of Mechanical Energy for Student Computation
Authors: Blisard Thomas J. , Duursema Charles H.
Published: August 2005

This apparatus was designed to provide data for sustained computations by engineering students in general physics and consists of a large pendulum swinging over a waxed-paper strip. The velocities of the ball at a number of positions are computed, the kinetic and potential energies are calculated for each position and plotted against the angle of displacement of the pendulum. The sum of the two curves when plotted is a horizontal line. Students interpret the total mechanical energy curve in terms of the conservation of mechanical energy. Student interest is motivated by the impressive size, visibility, and precision of the apparatus. The effectiveness of the demonstration is enhanced by using procedures simulating an engineering situation.
On Definitions in the Teaching of Physics
Authors: Chraplyvy Zeno V.
Published: August 2005

Reasons are discussed why certain rigorous definitions of physical quantities appear to be too difficult for the average student. A general criterion for pedagogically satisfactory definitions is proposed and illustrated by several examples; in particular, the definition of the magnetic field vector B by means of the Lorentz force is discussed in some detail. Remarks are added on the use of auxiliary “paradefinitions”
The First Reported Observations on Emission Spectra
Authors: Watson E. C.
Published: August 2005

The first person to use a prism to examine the light from colored flames was a young Scot named Thomas Melvill. He announced his results in a paper read before a philosophical society in Edinburgh early in 1752, less than two years before his death at the early age of twenty-seven. This paper, which was not published until 1756, is so rare that it seems desirable to reproduce a portion of it in facsimile in celebration of the 200th anniversary of its reading.
Graphical Solutions to Optical Problems of Three Different Types
Authors: Irons Eric J.
Published: August 2005

The following problems are considered:

I. Paraxial ray tracing by the focal plane method.—For spherical refracting and reflecting surfaces it is shown that by drawing two secondary axes, one parallel to a ray incident at an arbitrary angle and the other parallel to the path of the same ray after refraction or reflection, the positions of the focal planes are readily established and their necessary properties deduced. The same is done for a lens by a method based on the fact that a focal plane of the first surface is conjugate to a focal plane of the second surface.

II. The variation in the distance L between the conjugate foci of a thin lens (focal length f) with the distance l of one focus from the lens.—A general formula is established, and a simple construction for plotting the graphs between L/f and l/f is described.

III. Refraction by prism combinations and the prism refractometer.—A graphical method is used to discuss the design of the Amici prism, the direct vision spectroscope, and achromatic prisms giving appreciable deviations. A graphical method is also described for finding the refractive index of a liquid from results obtained with a prism refractometer.
On a Routine Analytic Method for the Solution of Problems in Statics
Authors: Simon A. W.
Published: August 2005

A routine analytic method for the solution of problems in statics is given. The method requires no geometry other than that required for the identification of the coordinates of certain cardinal points involved in the problem. The method is illustrated by the detailed solution of an actual case.
Behavior of Magnetic Materials
Authors: Bozorth R. M.
Published: August 2005

This is a review of recent work in which the atomic theory of ferromagnetism and the domain theory of magnetization are applied to new materials.
Surface Energy, A Mode for Energy Absorption During Impact
Authors: Rinehart John S.
Published: August 2005

The role that pulverization of the target material may play in absorbing the energy of an impacting missile is discussed. The energy that can be absorbed in this way will, in general, depend on the area of new surface that is created. Approximate calculations suggest that, for impacts against rock-like materials and glass, very considerable amounts of energy could be absorbed. The production of rock flour at the Barringer Meteorite Crater in Arizona is cited as an example.
Principal Frequencies of a Double Spring-Mass System
Authors: Pong William
Published: August 2005

The purpose of this paper is to show how the masses of the springs will affect the principal frequencies of a double spring-mass system. The frequency equation for the system is first derived from a set of assigned boundary conditions. Then with the assumption that the mass of each spring is relatively small, a special case is considered. It is shown by approximation that the mass of the spring has the equivalent effect of changing the main mass by an amount which depends on the modes of oscillations.
Reproduction of Prints, Drawings, and Paintings of Interest in the History of Physics. 55. Titlepage from Robert Grosseteste's Lines, Angles, and Figures
Authors: Watson E. C.
Published: August 2005

Probably no one had a greater influence upon English thought and literature during the thirteenth and fourteenth centuries than Robert Grosseteste. It is proposed to celebrate the seven-hundredth anniversary of his death by reproducing a curious woodcut, portraying the reflection and refraction of light, which forms the title page of his Libellus de Phisicis Lineis Angulis et Figuris (Nuremberg, 1503).
Discovery of the Differential Thermometer
Authors: Brown Sanborn C.
Published: August 2005

The differential thermometer was simultaneously discovered by Sir John Leslie and Count Rumford. The priority controversy between these two men is presented. Some years later Sir Humphry Davy depreciated Leslie's claim to the discovery. The ensuing debates cast interesting light on the personalities of the protagonists.
Installation and Operation of Ten-Kilocurie Cobalt-60 Gamma-Radiation Source
Authors: Nehemias John V. , Brownell L. E. , Meinke W. W. , Coleman E. W.
Published: August 2005

The expanding interest in studies of the effects of gamma radiation upon biological and chemical systems has encouraged the production of increasingly higher level sources for various institutions. Recently, at the University of Michigan, a ten-kilocurie cobalt-60 gamma radiation source has been installed and is now in routine operation. A brief discussion of some of the problems involved in installation and operation of such a source and some of the studies being undertaken is presented.
Father Procopius Diviš and His Lightning Conductor
Authors: Hujer Karel
Published: August 2005

A description of a grounded lightning conductor erected in 1754 in Přímětice, Moravia.
Electromagnetism without Magnetism: An Historical Sketch
Authors: Moon Parry , Spencer Domina Eberle
Published: August 2005

Maxwell's formulation of electromagnetism is not the only formulation, though it is the most familiar. In particular, the whole subject of electrodynamics can be expressed as an extension of Coulomb's equation, with the magnetic field entirely eliminated. The paper reviews the history of this attack, beginning with the work of Coulomb, Ampère, and Gauss, and concluding with recent developments.
A New Examination of the Laws of Thermodynamics
Authors: Green Robert B.
Published: August 2005

The first law is stated in a new, simpler form which is qualitative, and its quantitative content is proven as a corollary. This is done for both the Poincaré and the Carathéodory methods. A statement of the second law is given. Minimum requirements for statements of the laws are discussed, and new alternative statements suggested.
An Experiment on the Dielectric Constant of a Gas
Authors: Worrell Francis T.
Published: August 2005

An experiment is described wherein the dielectric constant of air is measured in a student laboratory. By using a beat frequency method, rather than a direct comparison, precisions of the order of 0.01 percent to 0.001 percent are obtainable with ordinary equipment. Important instructional features of the experiment are mentioned.
Comments on the Optics of Birefringent Crystals
Authors: Givens M. Parker , Discher Wendell V.
Published: August 2005

Some of the optical properties of biaxial crystals are reviewed. Particular attention is given to the shapes of the wave surfaces and to the fact that true conical refraction cannot be observed.
The Abbe Theory of Microscopic Vision and the Gibbs Phenomenon
Authors: Rogers G. L.
Published: August 2005

An elementary discussion of the Abbe theory of microscopic vision is given, suitable for teaching purposes. The effect of the phases in the back focal plane of the objective is briefly outlined. The consequence of limiting the aperture of the system in this plane is shown to be an image marred by diffraction.

The relationship to Fourier's theorem having been indicated, the Gibbs phenomenon is next described. A standard formula for the finite sum of a Fourier series is taken and adapted to the case of imaging a suitable grating with a microscope objective limited by a slit aperture. If the grating slits are very narrow compared with the opaque region separating them, the image of each is shown to be marred by a set of fringes, due to the Gibbs phenomenon, exactly equivalent to the diffraction fringes from the single slit in the microscope objective.
Allston Burr Lecture Hall, Harvard University
Authors: Hickman Roger W. , Kemble Edwin C. , Nash Leonard K.
Published: August 2005

A building designed for the physical science courses in the general education program at Harvard University is described. Numerous special features of the lecture halls contribute to their utility and convenience for the presentation of lectures in physical science to large groups of students.
A Way of Representing the Motion of a Classical System as Being along a Geodesic in Space-Time
Authors: Armstrong H. L.
Published: August 2005

Ordinarily, the Jacobi formulation of classical mechanics describes a system by giving the path of a “system point” in “configuration space,” the path being a geodesic if a metric is suitably defined. Nothing is said, however, about the motion in time.

It is suggested here that, by adding a degree of freedom in uniform motion to serve as a clock, and identifying the time with the coordinate of that degree of freedom, the configuration space can be extended to a space-time, in which the motion is completely described, both in space and in time, as being along a geodesic. Also, by this representation, the idea of “absolute time” is made unnecessary.

A representation such as this is, of course, normal in relativistic theory, but its use here in nonrelativistic mechanics is believed to have some novelty.
Paper Representations of the Noncubic Crystal Classes
Authors: Schiff L. I.
Published: August 2005

It is shown that the full symmetries of twenty-seven of the thirty-two crystal classes, all except the five cubic classes, can be exhibited by suitably marked pieces of paper or cardboard. It is necessary to use both sides of the paper, and to exploit its small but finite thickness.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 65. The Discovery of the Zeeman Effect
Authors: Watson E. C.
Published: August 2005

This article reproduces and interprets three stained glass windows that have been installed in the Kamerlingh-Onnes Laboratory at the University of Leiden to commemorate the discovery of the Zeeman effect.
Sesquicentennial of Christian Doppler
Authors: Hujer Karel
Published: August 2005

An account of some little-known phases of Doppler's struggling life is given at the occasion of his recent birthday anniversary. A brief analysis of Doppler's major work and its fundamental bearing upon modern astrophysics are also provided. Whether Doppler ever visited an astronomical observatory is not known. Spectroscopy and photography, which alone could prove Doppler's principle in astronomy, were still in their embryonic state during his productive years.
Intermediate Laboratory Experiment in Heat Conduction
Authors: Shaw C. H. , Saunders Norman
Published: August 2005

An experiment in single dimensional heat flow suitable for an intermediate laboratory course is described.
Rectangular Potential Well Problem in Quantum Mechanics
Authors: Pitkanen Paul H.
Published: August 2005

The one-dimensional rectangular potential well problem is one of the standard examples used in courses to illustrate quantum-mechanical properties. It has also been of value in the study of nuclear energy states. However, it is necessary to resort to graphical or numerical procedures at the last if one desires explicit values for the energy levels. It is the purpose of this article to point out a simpler and more perspicuous method of graphical solution than those used at the present time.
Air Suspension Gyroscope
Authors: Duane Bernard H.
Published: August 2005

A simple and challenging freshman laboratory experiment for the quantitative study of gyroscopic precession.
Electromagnetic Sonometer
Authors: Turner Alva
Published: August 2005

The sonometer to be described is unique because of its electromagnetic nature. Its application to the vibrating string experiment makes practicable an important experiment which has hitherto been difficult to perform. This sonometer makes it possible to demonstrate both sound and electrical experiments with very reliable results.
Isochronal Spiral Regulator
Authors: Broek J. A. Van den
Published: August 2005

In 1659 Christiaan Huygens invented the pendulum clock and realizing the lack of isochronism in a simple pendulum, he mounted it between cycloidal cheeks. After many years of trying to adapt this clock to seagoing vessels to determine longitude, he suggested, in 1675, the use of a balance wheel with an elastic wire to control oscillation. At this time the “theory of elasticity” was not sufficiently developed to analyze his balance arrangement.

The first successful effort to establish the laws of isochronism for a balance governed by spiral springs was made by Phillips (Annales des Mines, Tome XX, 1861). However, he did not discuss the problems raised by the use of regulator pins.

The present paper deals with the isochronal balance as influenced by the functioning of spiral springs equipped with regulator pins. To insure isochronal motion of a balance, the inner end of spiral regulator must act on the balance with a pure torque (a moment unaccompanied by any linear reactions), and this torque must be linearly proportional to the angular displacement of the balance. The design of terminals with regulator pins resolves itself to the problem of finding its shape so as to insure isochronal motion.
Oersted Medal Address
Authors: Eaton V. E.
Published: August 2005

Remarks by Professor V. E. Eaton on the occasion of his receiving the nineteenth Oersted Medal for notable contributions to the teaching of physics, at the twenty-fourth annual meeting, New York, January 28, 1955.
Physics in Engineering—A Problem In Appraisal
Authors: Ryder J. D.
Published: August 2005

The general objectives of a course in general physics for engineers are discussed. To ascertain whether these objectives are being met, the author has reviewed several leading physics textbooks and several basic engineering textbooks in equivalent areas. He is discouraged by the multiplicity of applied topics apparently discussed in the physics courses, without apparent major emphasis on concepts. He concludes that it might be better to ask the physics department to teach a course in atomic and nuclear physics, possibly at the junior or senior level, and allow Engineering to teach the fundamentals of the classical area as they are already doing to a large extent.
Acoustic Filter for Classroom Use
Authors: White J. E.
Published: August 2005

Many articles and text books have treated acoustic filters from various viewpoints, and acoustic filter experiments have been devised for laboratory courses in acoustics. These experiments frequently point out the analogy between lumped-constant acoustic filters and electrical filters, in order to make use of the many texts and handbooks dealing with electrical filter theory and construction. Although it is clear that electrical filters are designed to operate from a specified source impedance and into a specified load impedance, the laboratory experiments which the author has seen do not apply this requirement to the acoustic filters used. The present article describes an acoustic source with a primarily resistive output impedance, a microphoen assembly which serves as a primarily resistive load impedance and detector, and a low-pass acoustic filter designed to match them. The analogous electrical filter was built, and the performance characteristics of the two filters are compared.
Trends in Triodes
Authors: Andrews C. L.
Published: August 2005

In each decade prophets predict the maximum frequency which triode oscillators may ever attain. In each decade the limit is revised upward by a factor of two. The present upper limit for commercial triodes is about 6000 Mc/sec (5-cm wavelength). For each demonstration in physical optics there is a most convenient wavelength. Waves of 12 cm are most convenient for classroom demonstrations of the Fresnel diffraction. For the Fraunhofer and Bragg diffraction 5-cm waves are better. A microwave spectrometer for 5-cm waves is described.
Forced Vibration with Damping
Authors: Richards D. A.
Published: August 2005

The experimental determination of the response curves for forced vibration with velocity damping, using a moving-coil galvanometer, is described. The mechanism for producing a sinusoidal emf, of continuously variable frequency ranging from zero to 0.4 cy/sec, is described, together with a method for the determination of the phase angle between the driving force and the motion of the driven system. Experimental results, obtained with the apparatus, both for response curves and phase angle measurements, for various values of damping, are summarized in the paper.
Progress Report on Physics in Engineering Education
Authors: Seeger Raymond J.
Published: August 2005

This report reviews the activities of physics and engineering groups concerned recently with the problem of the role of physics in engineering education. In particular, it describes briefly the interest shown in physics education by the Committee on the Evaluation of Engineering Education of the American Society for Engineering Education, the activities of the American Society for Engineering Education through its Physics Division, of the American Association of Physics Teachers through its Committee on Engineering Education, and the consideration given the whole problem by the American Institute of Physics through a special committee. Other pertinent material such as the ASEE-NSF sponsored conferences on various aspects of physics in engineering education are included.
The Energy of Electric and Magnetic Fields
Authors: Park David
Published: August 2005

This note discusses the transition from the idea of the mutual potential energy of a static system of charges or currents to that of energy storage in a field. The argument is given first in a very simple form, where the transition can be made obvious, and this is followed by a more general discussion of the case in which permittivity and permeability are not independent of the applied fields.
Mechanical Forces on a Current-Carrying Conducting Cylinder
Authors: Jones E. E.
Published: August 2005

The magnetostatic field due to an elliptic cylinder carrying steady current in a nonuniform magnetic field is determined through the use of magnetic vector potentials and complex potential functions. The resultant force and couple on the cylinder are deduced and their forms investigated in the particular cases when (i) the cylinder is of circular section, and (ii) when the external magnetic field possesses a certain type of symmetry.
Electrical Measurement of the Speed of Light with a Clock and Measuring Rods
Authors: Clark George W.
Published: August 2005

An experiment is described for the complete determination of the ratio of the absolute units of charge. The only calibrated measuring instruments used are a meter stick, a micrometer, and a clock. The accuracy of the measurement is approximately 5%.
Classical Meson Theory. I
Authors: Kahana S. , Coish H. R.
Published: August 2005

Meson field theory is introduced from an elementary point of view in analogy with familiar classical fields. Three formulations are considered: scalar, pseudoscalar, and vector. In the symmetric theory the isotopic spin of a nucleon is taken to be a classical vector in charge space.
A Study of Postulates: The “Thermodynamic” Derivation of the Adiabatic Gas Law
Authors: Shanks D.
Published: August 2005

The adiabatic gas law, pvγ = const, is usually derived in thermodynamic textbooks as if it were a consequence of the first law of thermodynamics. It is shown here that the first law, and other assumptions made, are really irrelevant. These “thermodynamic” derivations are then analyzed in order to clarify the nature of the irrelevancies.
Network Theorems Applied to a Determination of the Resistance and Sensitivity of a Galvanometer
Authors: McCormick G. C.
Published: August 2005

Deflection methods used in laboratory courses for determining the resistance and sensitivity of a galvanometer normally involve errors due to contact potentials. Considerations underlying the avoidance of such errors are reviewed. A method of measurement using Thévenin's and other network theorems is presented. Resistance and sensitivity measurements over the complete scale range are readily made to within 0.15%.
Effect of Carbon Dioxide Variations on Climate
Authors: Plass Gilbert N.
Published: August 2005

Variations in the amount of atmospheric carbon dioxide cause temperature changes sufficiently large to influence the climate. If the atmospheric carbon dioxide doubles, the surface temperature rises 3.6°C; if it is cut in half, the surface temperature falls 3.8°C. Some of the factors that can be explained by the carbon dioxide theory are: during a single glacial epoch, the climate continually oscillates between a glacial and an interglacial stage with a period of tens of thousands of years with no stable state possible, when the carbon dioxide amount is below a certain critical value; the increased precipitation at the beginning of a glacial period; the time lag between the period of mountain building and the onset of glaciation; periods of glaciation occur at the same time in both hemispheres; the general warming of the climate in the last fifty years. The various factors that enter into the carbon dioxide balance and the influence of the oceans on the atmospheric carbon dioxide amount are discussed in detail. In contrast to other theories of climatic change, the carbon dioxide theory predicts a warming trend that will continue for centuries or as long as fossil fuels are burned in significant quantities.
Thermodynamic Theory of Irreversible Processes. I. The Basic Macroscopic Concepts
Authors: Miller Donald G.
Published: August 2005

The foundations of the thermodynamic theory of irreversible processes are presented in macroscopic terms. The concept of entropy production in systems with gradients is discussed in relation to classical thermodynamics and to what new hypotheses are necessary. The entropy production is computed in some simple cases, and it is found that its factors can be related to well-known linear laws such as Ohm's. It is shown on experimental grounds that the linear laws must be generalized in complex cases involving interacting flows. Further appeal to experiment shows that the Onsager relations must be valid. The range of validity of the theory is discussed.
Maintaining the Geometrical Alignment of a Large Accelerator
Authors: Crane H. R.
Published: August 2005

In proton accelerators now in the construction or design stages, it appears to be necessary to be able to make adjustments both radially and vertically over distances of several hundred feet with no error greater than 0.02 in. A scheme for accomplishing the required measurements is proposed.
Thermodynamic Theory of Irreversible Processes. III. The Potentials of Electrochemical Cells in Gravitational and Centrifugal Fields
Authors: Miller Donald G.
Published: August 2005

Using the thermodynamic theory of irreversible processes, a general equation is derived for the solution potential of a multicomponent fluid containing both charged and uncharged species situated in a gravitational or centrifugal field. The argument fully takes into account the irreversible processes of sedimentation and diffusion, and it is shown rigorously how the Hittorf transference numbers of ions and nonelectrolytes enter into the expression. The cell emf is derived and specialized for three cases of experimental interest; the concentration cell with transference, the homogeneous solution in the field cell, and the sedimentation equilibrium cell. These equations are applied to three common electrode systems with a single binary electrolyte in a single neutral solvent.
Some Current Problems and Needs in Science Education
Authors: Dees Bowen C.
Published: August 2005

Some of the current problems in science education (principally at the secondary school level) are discussed, and several possible methods of ameliorating present conditions are mentioned. The danger of “over-professionalizing” science instruction—to the detriment of the contribution science can make to the education of the nonscientist—is emphasized.
Classical Model of K Capture Inner Bremsstrahlung
Authors: Winter Rolf G.
Published: August 2005

As a classical model for radiative capture, a current loop that has initially a moment of one Bohr magneton and that decays with a mean life of ħ divided by the transition energy is considered. The shape of the low energy end of the spectrum and the total number of photons produced per capture are given correctly.
Measurement of High Resistance
Authors: Leifson S. W.
Published: August 2005

A method of measuring a high resistance by means of an inverted triode voltmeter is described. Simple and inexpensive apparatus is used. Complete data for plotting the charge and discharge curves of a condenser may be obtained in a few minutes. Being suitable for the general physics laboratory, the experiment gives students good practice in using and analyzing exponential and logarithmic curves.
Duration of Atomic Collisions
Authors: Oldenberg Otto
Published: August 2005

The conventional estimate of the duration of an atomic collision is the time required to cover an atomic diameter or, if there is a force of attraction, the period of one molecular vibration. Whereas this estimate is adequate for the duration of a head-on collision it fails for eccentric collisions. These are described by “effective potential curves,” which were originally introduced to represent dissociation of diatomic molecules by rotation and take into account the centrifugal force. These curves, different from the ordinary potential curves, show broad maxima outside of the well-known minima. The maxima slow down or even repel the approaching atoms. A pair of atoms whose energy carries it just to the top of a maximum may even perform a part of an unstable rotation. In the general case of eccentric collisions the durations cover a wide range between the period of a molecular vibration and the much longer period of a molecular rotation.
Lagrangian Formulation and Mechanical Interpretation
Authors: Bunge Mario
Published: August 2005

The question is asked whether, as is often claimed, the Lagrangian formulation of a physical theory provides its mechanical interpretation. For purposes of this enquiry, an analysis of physical theories is performed, with special emphasis on classical mechanics, electromagnetism, and quantum mechanics. Three aspects are distinguished and defined: the formulation (statement), the representation (transformation properties), and the interpretation (meaning). Confusion of formalism with meaning is criticized, and is suggested as a source of some misunderstandings of recent reinterpretations of quantum mechanics. Properties and advantages of Lagrangian formulations are listed, and it is recalled that their chief usefulness lies in that they are the most helpful precisely when mechanisms are either ignored or absent. It is concluded that Lagrangian formulations contribute to the demechanization of physics and that the program of reduction to mechanics has not succeeded in physics.
The Title of Maurolico's Photismi
Authors: Rosen Edward
Published: August 2005

The recent English translation of Maurolico's Photismi misinterpreted the title of that work and mistook its date of composition.
Concerning the Fellows of the American Physical Society
Authors: Hirsh F. R.
Published: August 2005

The biographies of two groups of Fellows, 1137 from the 8th edition of American Men of Science and 300 others from the 9th, are examined geographically with respect to places of birth, of award of Ph.D. degree, and job. Age-number spectra are plotted for both groups. Academic origins of the smaller group are investigated.
Fashions in Thermodynamics
Authors: Zemansky Mark W.
Published: August 2005

It is pointed out that thermodynamics is a useful subject in widely varying fields, such as engineering, chemistry, and physics. It is, however, used in such different ways by scientists in these fields, that one group hardly recognizes what the other is doing. Some of the controversies in the nomenclature of thermodynamics are mentioned and some of the changing styles in thermodynamics are explained in terms of the thermocouple. Some unfortunate tendencies in the teaching of thermodynamics are deplored. The author ends with a tribute to many of his former students.
Antinucleons. Richtmyer Lecture 1957
Authors: Segrè E.
Published: August 2005

The author describes the historical background on antiparticles and the experimental work that led to the discovery of the antinucleons. Many of the properties of the antiproton which can be predicted exactly on the basis of Dirac's theory have been verified. The outstanding problem is now to find the other properties which cannot be predicted on the basis of Dirac's theory and a start in this direction has been made. The latest experiments on cross-section measurements and modes of annihilation are described.
Model to Illustrate Some Properties of Vectors in Three Dimensions
Authors: Baez Albert V.
Published: August 2005

Vectors represented by thin rubber tubing may be used to illustrate the polygon rule for vector addition in three dimensions. The elastic model lends itself to illustrate multiplication by a scalar, the difference between vectors, a displacement vector which varies with time and the fact that the time derivative of a displacement vector is tangent to the trajectory even when it is not a plane curve.
Addition to the Ballistic Pendulum Experiment
Authors: Barnes George
Published: August 2005

An addition to the elementary ballistic pendulum experiment is described. The basis of the addition is the use of a pump-action pellet gun of accurate bore whose projectile can be fired at a relatively small velocity. By determining the drop of the projectile over a horizontal distance of about 40 ft, its muzzle velocity can be calculated. Comparison of results with those of the usual experiment gives rise to errors of 5% or less.
On the Structure of Atomic Nuclei
Authors: Bohr Aage
Published: August 2005

A survey is given of interpretations of nuclear properties based on the two differing models of nuclear structure, the liquid-drop model and the shell model. These can be considered to be two approximate representations of a structure that is is more complex than either. A more comprehensive model is discussed and shown to facilitate interpretation and correlation of the ellipticities of some nuclei indicated by the hyperfine structure of spectra, of rotational gamma-ray spectra, and of the process of Coulomb excitation.
Study of Collisions. Part. I. A Survey of the Periodical Literature
Authors: Barnes George
Published: August 2005

A review of the periodical literature on the subject of impact and the coefficient of restitution ε shows that it depends not only on the materials (elastic moduli) of the colliding objects, but also on (1) their relative normal velocity at the instant of impact, (2) their shapes and sizes, (3) their masses, and (4) the medium in which the impact occurs.
Simplified Approach to Spin in Dirac Theory
Authors: Mendlowitz H.
Published: August 2005

The usual definition of spin in the Dirac theory brings about peculiar results which one finds difficult to visualize from an intuitive standpoint. An approach to this problem utilizing the framework of the Foldy-Wouthuysen representation is suggested. Applications to the description of polarization of beams and scattering experiments are discussed.
On the Origin of Inertia
Authors: Rasor Ned S.
Published: August 2005

An intuitive concept of the origin of physical inertia is illustrated by elementary semi-quantitative calculations. Physical situations for which the concept predicts departure from the second law of motion are discussed.
Influence of Light upon the Magnetization of Massive Iron
Authors: Stauss H. E.
Published: August 2005

Recently Lamarsh has called attention to old experiments that indicated an influence of light upon the magnetization of massive iron. One of the experiments has been repeated under conditions as free as possible from disturbing conditions that may have influenced the original experiments. No influence of light upon the magnetization of iron was observed. The upper limit of possible change of magnetization in the specimen that may have escaped detection was one cgs unit of intensity of magnetization I.
Induced Rocking
Authors: Satterly John
Published: August 2005

Circular objects such as disks fitted with central spindles rest on a horizontal table in inclined positions which are in neutral equilibrium. If the disk is loaded eccentrically with a small body the disk will rest in stable equilibrium when that body is in its lowest position. If the whole is displaced to one side and released it will rock to and fro about that position. Theory and experiment are applied to find how the period of the rocking motion depends on the dimensions of the disk, spindle, and affixed body, the inclination of the spindle to the horizontal, and the masses and moments of inertia of disk, spindle, and affixed body. The expression found for the length L of the equivalent simple pendulum is L = I cosρ/ma, where I is the total moment of inertia of disk, spindle, and affixed body about the line joining the points of contact of the spindle and the disk with the table, ρ is the angle of inclination of the spindle to the horizontal, m is the mass of small affixed body, and a is the distance of the center of this body from the axis of the disk and spindle.
Thomson Atom
Authors: Zatzkis Henry
Published: August 2005

The historical development leading up to the Rutherford-Bohr model of the atom is briefly surveyed. The atomic model, suggested by J. J. Thomson before Rutherford's model, is investigated. The quantization shows that the bound states bear a marked resemblance to those of the hydrogen atom. However, the states are in general nondegenerate. Thus, the Thomson atom could not have survived the spectroscopic evidence even if no Rutherford scattering experiments had been performed.
Some Rigorous Results for a Model Imperfect Gas
Authors: Baker George A.
Published: August 2005

We show that the classical similarity relations and virial theorem imply particular forms for the internal energy and the equation of state in systems where the potentials are homogeneous of degree n. We also show that for these systems the laws of mechanics imply that the differential of entropy is exact. We deduce rigorously some experimental results which must hold for any gas whose constituent particles interact by means of a homogeneous potential. One physical situation in which this model may be expected to be valid is the case of a totally ionized gas with a superimposed radiation field.
Report to Physics Teachers on Procedures for Obtaining Surplus Government Property
Authors: Rhoten Walter G. , Barry L. K. , Kelly W. C.
Published: August 2005

Physics teachers and researchers in educational institutions can profit greatly from the surplus property program of the United States Government. Equipment and supplies of interest in physics are currently available through this program. Much additional surplus property could be transferred to educational institutions if greater numbers of physics teachers would participate vigorously in the program. This report brings up to date an earlier article on the subject and presents recommendations of ways in which physicists can use the program to greater advantage.
Logarithmic Spiral: An Ideal Trajectory for the Interplanetary Vehicle with Engines of Low Sustained Thrust
Authors: Bacon Ralph Hoyt
Published: August 2005

It is shown that a vehicle with engines of low sustained thrust can be directed along a logarithmic spiral through an inverse-square gravitational field by means of an extremely simple guidance system; it is possible to choose a spiral for which initial and final velocities are optimum.
Laboratory in Elementary Mechanics
Authors: Hazen W. E. , Dockrill A. G. , Lapointe M. , Thurston L.
Published: August 2005

A new laboratory program in elementary mechanics is described. Experimental methods have been devised to permit laboratory study of nearly all of the basic ideas of dynamics that are studied in the classroom. New instrumentation that proved necessary includes a synchronized timing system accurate to 1/100 sec, a simple stroboscopic camera, and various auxilliary devices. Statics is relegated to the role of a method for determining the forces employed in the dynamics experiments. The program of experiments is outlined.
Modified Helical Method for Determining e/m
Authors: Miller Bernard L.
Published: August 2005

In the helical method a cathode-ray tube is inserted in a solenoid and e/m determined from the condition for focusing deflected electrons to a spot on the screen. This has been modified by substituting alternating current in the solenoid and simultaneously supplying a voltage to the deflection plates proportional to the solenoid current. As a result, all electrons move in spirals of the same radius and the pattern observed is a portion of a circle (provided the beam has been properly centered). By adjusting the solenoid current until a full circle just appears, e/m may be deduced. The results obtained were consistent with those of the method using direct current, but were 6 to 9% low. The discrepancy was traced to using the distance from the screen to the rear of the deflection plates in the e/m formula, whereas an analysis showed it should be measured to the center of the plates. e/m was also obtained from the magnitude of the radius of the displayed circle.
Improving the Quality of Science Instruction in Elementary and Secondary Schools
Authors: Smith Herbert A.
Published: August 2005

This paper discusses the training of a science teacher and some factors accounting for so much ineffective science instruction. Some ways to improve the situation are suggested. The paper highlights some of the common misunderstandings and tries to establish a basis for more effective cooperation between scientists and educators.
Coaxial Cavity Oscillator and Some Experimental Oscillator Circuits
Authors: Dilley Norman R.
Published: August 2005

Some coaxial cavity oscillator circuits are described to supplement present laboratory course work in electronics or electricity and magnetism. The concept development aspect of the laboratory will be enhanced if the student can construct his own equipment for the experiment. The equipment described is simple and inexpensive.