bluuebunny/crossref_metadata_2025 huggingface dataset:
Shapes of Craters Formed in Plaster of Paris by Ultra-Speed Pellets
Authors: Rinehart John S. , White W. C.
Published: August 2005

Observations have been made on the craters produced in plaster of Paris targets by steel pellets that weighed 2 g and impacted at a velocity of 2.5 km/sec and by aluminum pellets that weighed 23 g and impacted at a velocity of 4.7 km/sec. The angle of impact was varied from normal incidence to 75°. For angles of incidence between 0° and 45°, the mouth of the crater was substantially circular. At 60°, it had roughly the shape of an arrowhead. At 75° obliquity, the pellet ricocheted and produced an elliptical crater.

The area of the mouth of the crater in every case was many times the area of the impacting particle. The craters were characterized by a large bowl-shaped excavation from 12 in. to 1 in. in depth with a shaft that extended a few inches into the plaster and whose area was approximately that of the pellet.

The volumes of the holes have been measured and related to the impacting energy and momenta of the respective pellets.
Space at Mid-Century
Authors: Schlegel Richard
Published: August 2005

The concepts of space which are used in contemporary physics are discussed, and are contrasted with the older concepts associated with Newtonian physics. The effects of uniform motion on space and the simplest currently accepted relations between space and time are stated. Deviations from three-dimensional orthogonal space as demanded by the general theory of relativity are discussed, with attention to the relative roles of space and time terms in the space-time curvature associated with gravitational fields. The development of cosmo-logical theory, on the basis of general relativity concepts, is briefly indicated. Mach's suggestion for the relation of matter and space is described; more recent speculations relating over-all space and local properties, and the possibility of discontinuity in microscopic space, are noted. The emphasis in the current conception of space on interdependence between space and matter is pointed out.
A Demonstration of Wave Fronts, Attenuation, and Diffraction
Authors: Moore W. Cullen
Published: August 2005

The concept of wave fronts, defined as points of like phase, can be demonstrated by the use of an audiofrequency oscillator, a loud-speaker, a microphone, and a cathode-ray oscilloscope. The shapes of wave fronts radiated from plane, line, and point sources and the attenuation of intensity with distance can be qualitatively demonstrated. The double slit diffraction pattern can be explored as a function of the wavelength, slit spacing, and distance to the plane of observation in a simple arrangement of equipment.
A Demonstration Experiment on Positron Annihilation
Authors: Levinger J. S.
Published: August 2005

A lecture demonstration on positron annihilation is discussed. By use of two small Geiger counters and a standard Rossi coincidence circuit, we were able to demonstrate that the two annihilation photons go in opposite directions. A special arrangement of lead shielding is suggested.
Microwave Resonance Absorption in Antiferromagnetic Materials
Authors: Maxwell Louis R.
Published: August 2005

Microwave resonance absorption in Cr2O3, MnO, MnF2, and CoO above and below the paramagnetic-antiferromagnetic transition temperature is reviewed. The amount of the absorption decreases abruptly in lowering the temperature of the sample through its Curie temperature. The nature of the crystal structure changes associated with the changes in magnetic structure are given for comparison. With the exception of CoO, the alignment of magnetic ions to form the antiferromagnetic configuration results in a deformation along an axis perpendicular to sheets of magnetic ions having parallel spins. Similar results are reported for magnetite.
Projects in Electrical Laboratory
Authors: Williamson Charles
Published: August 2005

After performing nine standard experiments, the student chooses a project from a list of eleven for which the department has the necessary apparatus. Some of these projects require independent thinking and planning; others require only intelligent and selective use of printed references. Three men ordinarily work together, planning and executing their project in four weeks, with minimum help from the instructor. Each team hands in a written final report and may make an oral progress report to the class. Surprising enthusiasm is generated, and much is learned about the management of a small research project. A list of project titles appears in this paper.
Geometrical and Graphical Representations of Lissajous Figures
Authors: Fahy Edward F. , Karioris Frank G.
Published: August 2005

The fact that a sine curve, wrapped on the surface of a circular cylinder and projected orthogonally on a plane, will in certain cases produce Lissajous figures is used to develop a simple geometrical model which will demonstrate these curves. It is pointed out that natural generalizations of Lissajous figures can be obtained through this model.

The use of sine-sine graph paper for plotting and analyzing Lissajous figures is also described.
A Simple Arrangement for a Rotating Cylinder Viscometer
Authors: Hibberd F. H.
Published: August 2005

A modification of the rotating-cylinder method of measuring coefficients of viscosities of liquids, suitable for advanced laboratory classes, is described. The terminal angular velocity is measured for a series of driving torques and of depths of liquid. End effects can be eliminated by appropriate treatment of the data.
Some Considerations of an Employer Hiring Physicists for Applied Research
Authors: Chapman Seville
Published: August 2005

Applied research and development in industrial laboratories are contrasted with traditional university research. Various characteristics of scientific workers for applied research are classified as indispensable (intelligence, social adaptability, ability to use the English language, integrity), important (industriousness, initiative, intellectual curiosity, imagination, ingenuity), and desirable (experience, knowledge).
Velocity-Dependent Potentials for Particles Moving in Given Orbits
Authors: Coffman Moody L.
Published: August 2005

Velocity-dependent potential functions can sometimes be used to determine the field of force that can be applied in order that particles may move in specified paths. In particular, the electromagnetic field vectors E and B can be determined from such a potential function if the paths on which charged particles move are specified.

The velocity-dependent potential U is related to the kinetic energy T and the Lagrangian function L by the equation U = T − L, where L is an arbitrary solution of the Lagrange equation (d/dt)(δL/δp′) − (δL/δp) = 0, where p = constant represents the orthogonal trajectories of the curves which describe the paths the particles are to follow. From the velocity-dependent potential function U, the field of force can be calculated by the definition Qp = −(δU/δp) + (d/dt)(δU/δp′).
Undergraduate Origins of American Physicists
Authors: Cooper John N.
Published: August 2005

The number of physicists listed in the 1949 edition of American Men of Science who have received their undergraduate degrees from various colleges and universities has been tabulated. For each institution the ratio of the number of listings in physics to the total enrollment has been computed. A comparison of these data with those available from previous editions suggests that universities having major graduate programs in physics are becoming increasingly important in the training of undergraduates.
Experimental Study of Sliding Friction
Authors: Maney Charles A.
Published: August 2005

This article constitutes a report on an independent experimental study of the variation of the coefficient of sliding friction under very simple laboratory conditions. It is based on nonaccelerated motion involving sliding friction at speeds from 0.25 to 20 cm/sec. The experimental set-up consists of a weighted block resting upon a horizontal surface, subjected to the pull of various weights suspended over a pulley and attached to the block by means of a cord.

For all materials tested, including wood, leather, glass, and various metals, it is found that (1) the coefficient of sliding friction varies as the logarithm of the speed of the moving surface, increasing directly as the logarithm of the speed increases, (2) in the case of wood surfaces in contact, the coefficient of sliding friction decreases as the normal force increases, (3) in the case of both wood and leather surfaces in contact with other surfaces, the coefficient decreases with repeated performance, and (4) in the case of metal surfaces in contact, the coefficient of friction increases with repeated performance, unless the product of the abrasive action of friction is removed for each performance. The removal of the loose metallic particles causes a decreased coefficient of friction.
A Study of a New Arresting Device for Fletcher's Acceleration Apparatus
Authors: Wadey W. G.
Published: August 2005

A new mechanism for rapidly absorbing the kinetic energy of the cart in Fletcher's apparatus is described, and experiments to determine the physical basis of its operation are discussed. It is shown that the energy is absorbed by viscous flow.
Conditions for the Derivation of the Stress Deviator Tensor
Authors: Anderson Orson L.
Published: August 2005

The decomposition of the stress tensor into the spherical stress tensor and the stress deviator found in theories of plasticity is shown to depend upon the postulate that the stress tensor is the tensor sum of two physically independent stress constituents. The decomposition is derived by two different methods, the first method based on energy arguments, and the second method based on cause and effect arguments.
Opportunities and Rewards in Physics Teaching
Authors: Knowlton A. A.
Published: August 2005

Response to the presentation of the Oersted Medal of the American Association of Physics Teachers, February 1, 1952. The article is directed particularly to young physicists and is intended to present some of the more attractive features of small college teaching for their consideration.
The Prismatic Curvature of Spectral Lines
Authors: Gates David M.
Published: August 2005

A review of the early papers on the curvature of spectral lines is presented. The formulas for the oblique refraction of a light ray incident upon a boundary between two media are derived by means of Fermat's principle. These results are applied to the prismatic refraction of the oblique rays that originate at the off-axis positions of the spectrometer entrance slit. Three algebraic forms for presenting the resultant curvature of the slit image are given. Graphical results are presented relating the radius of curvature with the index of refraction of the prism at constant prism angles. Comparison is made with the curvature caused by reflection from a plane grating.
The Scattering Theory of the Schrödinger Equation
Authors: Park David
Published: August 2005

The Schrödinger equation for the scattered particle is converted into an integral equation, in which the kernel is obtained by the use of the condition that the events described by the solutions of the equation must be causally related, i.e., that causes must always precede the effects which they produce. The integral equation is iterated once, and it is found that its solution corresponds to the usual description of a scattering process in terms of an undeflected wave traversing the system plus a radially scattered wave moving outwards. In the second part, it is shown that a simple relation exists between solutions of Schrödinger's equation of the sort just described and the solution of the initial-value problem associated with the equation of motion for a free particle. By this means a solution of the scattering problem is set up which describes how the wave function develops as the wave which it describes propagates through the system. The series which results was first given by Feynman. As an example, the first Born approximation for the scattering problem is developed by each approach.
On the Physics of Harmonicas
Authors: Simon A. W.
Published: August 2005

Several studies and researches carried out in connection with the manufacture of harmonicas are briefly reviewed. A stroboscopic device used in tuning the harmonica reeds and a constant pressure device for sounding them during test are described. The manufacture of the reeds is discussed in some detail. It is pointed out that the primary problem in the manufacture of harmonicas is to produce them at a cost which will meet European competition. It is concluded that harmonica manufacture presents interesting problems for the physicist, engineer, and metallurgist.
A Direct Treatment of the Foucault Pendulum
Authors: Noble William J.
Published: August 2005

The equations of motion of the Foucault pendulum are set up in polar coordinates. The oscillation is shown to be simple harmonic for a particular angular velocity, −Ω sinφ, where Ω is the angular velocity of rotation of the earth and φ is the latitude. In general, the motion involves a constant areal velocity c and a nonlinear oscillation given by r̈+ω2r−c2/r3 = 0. This equation is integrated through the energy equation and shown to give the same precession as in the harmonic case.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics 46. Portrait of Christiaan Huygens by C. Netscher
Authors: Watson E. C.
Published: August 2005

This note points out that excellent reproductions in color of Netscher's fine portrait of Christiaan Huygens may be purchased at small cost from the Municipal Museum, the Hague.
Bodies Rocking on Planes and Cylinders, Spheroids and Spindles Rocking on Planes, Balls and Other Symmetrical Bodies Rocking in Elliptical and Other Holes
Authors: Satterly John
Published: August 2005

In continuance of earlier work (references below) the rocking of bodies of other shapes resting on different supports has been studied. The examples afford a useful study of the dynamical equations appropriate to such vibrations and provide simple and inexpensive experiments for students in the laboratory. Rocking bodies are often observed in every day occurrence, and interest in such motion is well worth development.
Quantum Mechanics and Thermodynamic Continuity
Authors: Landé Alfred
Published: August 2005

The basic concepts and rules of quantum mechanics are shown to be immediate consequences, on the basis of simple reasoning, of a postulate of continuity in the domain of macroscopic thermodynamics. The continuity principle leads first to the concept of a fractional likeness between two states in general, as opposed to the classical alternative of either like or unlike. Then all possible states of a system can be arranged in sets of mutually unlike or “orthogonal” states, with members A and B of different sets interconnected by fractional likeness factors q(A, B) between zero and unity. These factors q are identical with the relative intensities in a splitting effect of a state into components, ruled by probability relations and by the basic principle of quantum statistics of not counting permutations of individual particles. The problem of relation between the various fractional likenesses, or probabilities of transition under analysis, is a purely mathematical problem and is solved by the introduction of probability amplitudes necessarily subject to a matrix law of multiplication, i.e., to the principle of superposition. Thus, starting from the continuity postulate of thermodynamics, quantum theory in its general outline is obtained by simple reasoning. All further details, such as the duality of waves and particles, the uncertainty relation, and the mechanics of special systems, need only one more bit of empirical information, namely, the symmetric and periodic form of the amplitude ψ of fractional likeness between a state of given coordinate and a state of given momentum.
Path Concepts in Hamilton-Jacobi Theory
Authors: Landauer Rolf
Published: August 2005

It is pointed out that the classical analog to a wave function is not a single orbit but a set of paths as defined by the solution of the Hamilton-Jacobi equation. A review is given of Hamilton-Jacobi theory in language appropriate to these path concepts. It is shown that there is a classical analog to a wave packet. Quantum-mechanically, constants of motion are not arbitrary but must be characteristic values of commuting operators. It is shown by examples that the possible classical states are similarly restricted. The conditions are discussed under which a classical set of paths is derivable from the solution of a Hamilton-Jacobi equation.
Reproductions of Prints, Drawings and Paintings of Interest in the History of Physics. 47. The Heyday of Electrostatic Experimentation
Authors: Watson E. C.
Published: August 2005

Two contemporary engravings showing early electrical experiments are reproduced together with an entertaining account of such experimentation written by Park Benjamin in 1895.
Liquid Scintillation Counters
Authors: Falk C. E. , Poss H. L.
Published: August 2005

A review of the present status of liquid scintillators is given. The theory explaining the properties of the counters is discussed. Preparation of counters is described and counter characteristics such as emission spectra, response to various nuclear radiations, counting efficiencies, and emission intensities from various scintillating solutions are given. The applications of liquid scintillation counters in various fields of nuclear physics are discussed.
On the Theory of Dipole Interactions with Metals
Authors: Czyzak S. J.
Published: August 2005

The classical and quantum-mechanical interactions of molecular dipoles and metallic surfaces are derived and numerical calculations given for several molecule-metal pairs. The results represent the permanent dipole contributions to the total van der Waals interactions. The bearing of the dipole interactions on the problem of adhesion is discussed.
On the Physical Interpretation of Solutions of the Dirac Equation for a Free Particle
Authors: Neamtan S. M.
Published: August 2005

The usual choice of an orthogonal set of four plane-wave solutions of the free-particle Dirac equation does not lend itself readily to direct and complete physical interpretation except in low-energy approximation. A different choice of solutions can be made which yields a direct physical interpretation at all energies. Besides the separation of positive and negative energy states there is a further separation of states for which the spin is respectively parallel or antiparallel to the direction of the momentum vector.
Concerning Statistical Fluctuations in Radioactive Phenomena
Authors: Rodgers Eric , Rodgers Sarah H.
Published: August 2005

A recent paper by Grundl, Karioris, and Barkow on statistical fluctuations in radioactive phenomena is discussed. It is shown how their theory may be improved. Also, some results of experiments on the same subject by the present authors are presented.
Quantum Effects in the Radiation from Accelerated Relativistic Electrons
Authors: Schiff L. I.
Published: August 2005

The radiation associated with the operation of a betatron or synchrotron, due to the transverse acceleration of relativistic electrons by the magnetic field of the machine, is discussed qualitatively. Order of magnitude expressions for the angular opening of the cone within which the radiation is emitted, and for the wavelength of the maximum of the radiated spectrum, are obtained by means of qualitative arguments based on classical physics. It is then shown, from a consideration of the rate of spread of a wave packet that describes the electron, that quantum effects are negligible so long as the ratio γ of the total energy to the rest energy of the electron is small in comparison with the square root of the ratio of the orbit radius R to the reduced Compton wavelength λ̄c of the electron. This criterion for the validity of classical theory is substantially equivalent to, but not identical with, the commonly accepted criterion γ2≪R/λ̄c, which is derived from the assumption that the momentum of an emitted photon must be small in comparison with the momentum of the electron. Thus classical theory is expected to be valid for electron energies small in comparison with 1015 ev if the magnetic field strength does not exceed 104 oersted.
On the Zitterbewegung of the Dirac Electron
Authors: Huang Kerson
Published: August 2005

The detailed motion of a free Dirac electron is investigated by examining the expectation values of the position r and of r×ṙ in a wave packet. It is shown that the well-known zitterbewegung may be looked upon as a circular motion about the direction of the electron spin, with a radius equal to the Compton wavelength (divided by 2π) of the electron. It is further shown that the intrinsic spin of the electron may be looked upon as the “orbital angular momentum” of this motion. The current produced by the zitterbewegung is seen to give rise to the intrinsic magnetic moment of the electron.
An “Original” Experiment in Heat for the First-Year Laboratory
Authors: Barbour Ian G. , Kerman Ralph O.
Published: August 2005

There is need for elementary experiments in which the “research spirit” is present. Such an experiment involving the measurement of low temperatures has been used in both general physics and physical sciences laboratories. Each pair of students is required to devise its own method for measuring the temperature of a dry ice-alcohol mixture, to design and construct its apparatus, to carry out the measurement, and to report back to the whole group at the close of the laboratory period the following week. Stronger student motivation and insight into basic factors involved in experimental procedure have been among the outcomes of this experiment.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 48. William Hyde Wollaston and the Discovery of the Dark Lines in the Solar Spectrum
Authors: Watson E. C.
Published: August 2005

That the spectrum of sunlight is crossed by dark lines was observed for the first time by William Hyde Wollaston in 1802. In celebration of the 150th anniversary of this important discovery, Wollaston's announcement is here reproduced.
Optical Filters
Authors: Mohler Nora M. , Loofbourow John R.
Published: August 2005

In Part II of this survey of filters useful in optical work are included descriptions of polarization, interference, and Christiansen filters, and devices occasionally used in lieu of filters such as focal isolation and residual ray apparatus, gratings, and powder films used effectively as scatterers. Absorption type filters were surveyed in Part I.
Achievement of Physics Students With and Without Laboratory Work
Authors: Kruglak Haym
Published: August 2005

Two general physics laboratory groups were compared in achievement with a group enrolled in the same course without laboratory. The achievement was measured by two pencil-paper examinations and two laboratory performance tests. The analysis of variance and covariance method was used to hold constant three measures of initial differences among students. There were no statistically significant differences between the means of the groups on the mechanics theory test. The laboratory groups were significantly better than the no-laboratory group on all tests dealing with laboratory work.
Particle Properties of Radiant Energy in Wave Guides
Authors: Raudorf Walter R.
Published: August 2005

The mean energy per excitation wavelength of e.m. radiation propagated along a lossless uniform wave guide is found to be w = Qμ, Q being independent of frequency for a given amplitude of the longitudinal field intensity, mode of the field, and structure of the guide. The frequency μ and the group velocity vg of the radiant energy are related by the equation μ/μc  = [1 − (vg/c)2]−12 where μc = c/λc denotes the frequency at cutoff, and λc the excitation wavelength at cutoff. This equation permits one to put hμ = hμc+hμc{[1 − (vg/c)2]−12 − 1}. The amplitudes of the field intensities are chosen such that Q equals Planck's constant h. Applying the mass-energy relation, the term hμc = hc/λc = m0c2 may be interpreted as the “potential” (= rest) energy of the quantum hμ and m0 as the rest mass. The momentum p associated with hμ is found to be p = h/λg, λg being the wavelength along the guide. When radiant energy passes from one guide into another one of different cross-sectional structure via a tapered piece of wave guide, a partial conversion of “potential” to “kinetic” energy, and vice versa, occurs along the tapered section. In the case of TEM waves, which, however, can only be supported in a guide of infinite transverse dimensions, the group velocity becomes c and the rest mass zero.
On Fluid Dynamics in Physics Teaching
Authors: Seeger R. J.
Published: August 2005

In the light of private answers suggested for the public questions: What is physics? What is education?, a critical review is made of fluid dynamics in physics teaching. First, general physics is examined for what is being done in teaching fluid dynamics in physics. A critical analysis is made in particular of the important Bernoulli theorem as to what it is, what it says, what it means, and how it is used. Second, theoretical physics is examined for what is being done. In this case, the motion of a sphere has been selected as illustrative of present teaching. The typical course in theoretical physics is then examined with respect to its material about the motion of a sphere, both in a perfectly inviscid fluid and in a perfectly viscous fluid. This academic material is compared finally with experimental observations, particularly those in wind tunnels and in ballistics ranges. In conclusion, questions are noted on the foundations of fluid dynamics, particularly the role of viscosity, turbulence, the concept of a steady state, and the role of heat. The review ends with a moral question as to the students' stake.
Possible Motions of a Sphere Suspended on a String (The Simple Pendulum)
Authors: Hughes J. V.
Published: August 2005

The possible motions of a sphere suspended on a string are found to consist of combinations of (1) a pendulum type of motion and (2) a rolling motion, in which the ball rolls in angular harmonic motion about an axis very near its center. For (1) it is shown (a) the usual formula for the length of the equivalent simple pendulum should be replaced by L(1+2r2/5L2+4r3/25L3 +···), where r is the radius of the ball and L the distance of point of suspension to center of the sphere, and (b) the best way of starting this motion is to pull the ball aside by a horizontal force through its center. For (2) it is shown that the period of oscillation is very close to 2π(2r/5g).

Photographs are given showing experimental verifications of these effects.
An Electronic Differential Analyzer
Authors: Symon Keith R. , Poplawsky Robert P.
Published: August 2005

An electronic differential analyzer designed primarily for classroom teaching is described. The value of building such a device as a project for advanced students is emphasized. The method of setting up differential equations on the differential analyzer is explained, and a few sample solutions are illustrated.
A Graphical Demonstration of White Light Interference
Authors: Traub Alan C.
Published: August 2005

A teaching device is described which can be used in lectures on the interference of white light. The wave forms of four selected components of white light, in the violet, green, yellow, and red regions, are shown one above the other on a cardboard chart, inked in their respective colors. A sheet of clear plastic with an identical set of waves drawn on it is placed over the chart so that the two sets are in register. The combination represents a beam of white light as it arrives at the retina. A retardation of part of the beam is illustrated by displacing the plastic sheet laterally. Since the sine waves differ among themselves in wavelength, the various phase changes which result among the four components are shown quite clearly.

The principle has been embodied in slide rule form with the wave trains appearing at a large plastic window. Five smaller windows indicate, respectively, path difference in millimicrons, dominant wavelength and purity of the resulting light when C.I.E. Illuminant C is used, and relative energies and resultant hue for the four components shown.
The Definitions of Magnetic Flux Density and Field Intensity
Authors: Hughes J. V.
Published: August 2005

The present theory of magnetism, in which it is treated as a phenomenon of current electricity, suffers from objections which are pointed out. The meanings of B and H on an atomic scale are considered, and a method of picturing B and H, inside a ferromagnetic body, without mentioning magnetic poles or dipoles, is developed. It is shown that this method satisfactorily accounts for the demagnetizing field in certain simple cases and that it also makes clear why H occurs in the circuital theorem while B is used in Laplace's equation. Rigorous definitions of B and H at any point in a magnetic medium are then developed. In the concluding section the advantages of the suggested method are summarized.
A Classroom Antenna Experiment
Authors: Zieman Clayton M.
Published: August 2005

This article describes equipment for studying antenna patterns without the use of cumbersome outdoor apparatus. Patterns for numerous arrays, in good agreement with theory, are readily obtained. Construction of arrays observed by students is encouraged.
Application of Dirac's δ-Function to Some Problems in Classical Physics
Authors: Kothari L. S.
Published: August 2005

The Dirac δ-function is used in solving the problem of bending of a beam and also some problems of vibration. It is seen that fairly general results can be obtained without complicated calculations.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 51. Caricature of Sir John Leslie
Authors: Watson E. C.
Published: August 2005

An excellent caricature of Sir John Leslie, Professor of Natural Philosophy in the University of Edinburgh and inventor of the differential thermometer, was made by John Kay shortly before his death. It is here reproduced together with some amusing biographical notes.
The Closed Differential Pulley: Analysis of Its Rotational and Linear Motions
Authors: Dodd Laurence Ellsworth
Published: August 2005

A mechanical system of special design, primarily for instructional purposes, is proposed, mathematically analyzed, and tested experimentally. It may be regarded as a hybrid form between the compound wheel-and-axle and the differential pulley or chain hoist. Although the design is simple, the analysis is not too obvious at the start, and is somewhat complicated, exhibiting coordinated angular and linear motions with constant accelerations due entirely to the weight of the movable pulley. While the analysis assumes no friction, the actual heat loss can be readily calculated from time and displacement measurements and the equivalent friction force determined. Numerous equations and numerical data are included. The system offers various challenges to student interest in classical mechanics, both on the lower-division and advanced levels. Particular experimental work is suggested and analytical exercises given for use by teachers.
Elementary Theory of Neutron Sources in Reactors
Authors: Masket A. Victor
Published: August 2005

The basic physical and mathematical ideas involved in the use of a neutron source in reactors in the steady state are developed from the diffusion theory of neutrons of one energy group. The ideas are fundamental to more general and difficult discussions in published material and should serve as a helpful preliminary to the formal study of reactor theory.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 52. Frontispiece and Vignette from Chérubin's La dioptrique oculaire
Authors: Watson E. C.
Published: August 2005

Chérubin's La dioptrique oculaire (Paris 1671) is an unusually beautiful scientific work. The frontispiece and a vignette engraved by Edelinck are here reproduced and commented upon.
Demonstrations with Half-Wave Plates
Authors: Winans J. G.
Published: August 2005

Cellophane of thickness to give 180° phase difference between O and E beams may be combined with polarizing sheets to make three types of windows. A design is cut in the Cellophane and it is mounted on the polarizer with effective optic axis 45° to the plane of vibration transmitted. The three types are (a) linear polarizer with half-wave Cellophane (b) linear/circular polarizer with half-wave Cellophane mounted on the side opposite the quarter-wave plate (c) linear/circular polarizer with half-wave Cellophane mounted on the same side as the quarter-wave plate.

Two windows of type (a) give eight different patterns depending on the arrangement. One window of type (a) permits detection of small degrees of polarization. With one window of type (b) and one of type (c) there are six possible patterns two of which do not change with rotation of one window with respect to the other. These effects result from the ability of a half-wave plate to rotate the plane of vibration through any angle or reverse the sense of circularly polarized light.
Sustained Foucault Pendulums
Authors: Mackay R. Stuart
Published: August 2005

The time-delay or phase-shift effects crucial to the operation of ordinary doorbells and buzzers can be employed to sustain a Foucault (or other) pendulum in a very simple manner, not involving any electrical contacts. Some new electrical effects as well as the pendulum itself are discussed.
Advances in Knowledge of Nuclear Forces
Authors: Breit G. , Hull M. H.
Published: August 2005

The paper is primarily a review article covering work within the last five years preceding the summer of 1952. The principal features of experimental results on nucleon-nucleon scattering are summarized. The main conclusions of the theory of nuclear forces are reviewed with an attempt at a distinction between knowledge and speculation. The photoelectric effect of the deuteron, evidence regarding isobaric states from meson physics, the proof of the pseudoscalar character of the π-meson are briefly discussed as part of the main problem, and a partial account is given of relevant progress in the fields of binding energies of light nuclei and shell theory.
The New Physics Building at the Ohio State University
Authors: Oetjen Robert A. , Cooper John N.
Published: August 2005

The new Physics Building at the Ohio State University is described and pictured. Floor plans are shown and special features of the building are discussed.
Three Lecture Room Demonstrations in the Field of Electricity
Authors: Kolossvary Bela G.
Published: August 2005

Semiquantitative verification of the impedance formula for series circuits containing inductance and capacitance, phase relations in similar circuits including the case of resonance, and a triode oscillator operating in the frequency range from 2 cycles/sec to 20 000 cycles/sec, all based on a dissectible transformer, are described.
Longitudinal Vibrations of a Vertical Column by the Method of Laplace Transform
Authors: Hall L. H.
Published: August 2005

An interesting illustrative problem in mechanics is the motion executed by a vertical rod or column when it suffers sudden loss of support at the bottom. A solution is presented by the method of Laplace transform in two alternative forms: one represents the motion as a superposition of free fall and two oppositely directed progressive waves equal in amplitude and form; the other, as a free fall and a pulse, initiated at the bottom and propagated up and down the column upon reflection at the ends.
A Proposed Procedure for Selecting and Using Symbols for Physical Units
Authors: Roller Duane
Published: August 2005

Since the symbols—names, or their abbreviations—for physical units may be incorporated in physical equations in exactly the same manner as are the letter symbols for physical quantities and the numerical symbols, it follows that the rules for selecting and using these unit-symbols should be formulated in the light of established mathematical procedures. A set of such rules is proposed. Symbols are suggested for 185 commonly used units and combining forms.
Experimental Reactor Physics Course at the Oak Ridge School of Reactor Technology
Authors: Klema E. D. , Stephenson R. J. , Taylor S.
Published: August 2005

The curriculum of the Oak Ridge School of Reactor Technology includes a laboratory course in reactor physics. The first experiments are concerned with the fundamentals of nuclear physics and the later ones are of direct relevance to reactor engineering. The laboratory manual of the course is available as AECU-2164.
An Undergraduate Experiment for the Determination of Alpha-Particle Range
Authors: Michels Walter C. , Wiener Eva
Published: August 2005

Simple apparatus, using a scintillation counter with a 931-A photomultiplier, is described. The range of alpha-particles from Po210 is determined with this apparatus by varying the pressure in a shielded container, keeping the geometry constant. Data are presented on a 0.06 millicurie source, yielding a range of (3.81±0.03) cm at 760 mm Hg and 15°C. This value is obtained after correction for finite source thickness. The experiment offers particular value in giving students an opportunity to consider statistical fluctuations and to analyze the effects of finite source thickness, straggling, etc.
A Course in Radioactive Determinations
Authors: McFarland Robert H. , Hein Richard E.
Published: August 2005

A lecture-laboratory course in the use of radioactive isotopes is discussed. The scope of the material presented should furnish adequate initial training for persons whose future may be expected to include work with radioactive materials.
The Physics of Microwave Calorimeters
Authors: Okress Ernest C.
Published: August 2005

The electromagnetic reflection characteristics of a system of nonideal isotropic dielectrics in nearly ideal wave guides are formally developed. The general analytical results are applied to several cases of practical importance. Consideration is given to the manner of deriving optimum characteristics of flow calorimeters normally used for microwave measurements of power. Other applications include the determination of the complex dielectric constant of high loss quid dielectrics. Considerations relating to bandwidth of microwave calorimeters are included.
The Prenatal History of Electrical Science
Authors: Roller Duane , Roller Duane H. D.
Published: August 2005

The history of electricity was at first the history of the “amber effect,” that is, of the “attraction” for light objects displayed by rubbed amber. This effect was well known in antiquity and was coupled and confused with the attraction for iron by the loadstone. The earliest explanations of these phenomena were anthropomorphic, being followed, in classical antiquity, by teleological organismic explanations and also materialistic mechanistic explanations. In the 15th century the lack of a directive (north-south) property in amber was noticed. By the 16th century several substances exhibiting the amber effect were known. From this time onward, attempts were made to provide a theory for the amber effect independently of magnetic phenomena. Effluvium theories, so important in the later history of electricity, first began to develop in the 16th century. The present paper covers the period up to the work of Gilbert in 1600.
A Survey of Elementary Physics Laboratories
Authors: Brown Sanborn C.
Published: August 2005

Results of a survey of the physics laboratories in about twenty-five colleges and universities are reported. Problems of administration, teaching methods and techniques, scope and content, and finance have been studied in relation to the size of the student load in the elementary laboratory courses in physics.
The Motion of a Conducting Sphere in a Uniform Magnetic Field
Authors: Besdin D. J. , Shewell J. R. , Ikenberry Ernest
Published: August 2005

The motion of an uncharged, homogeneous, solid conducting sphere in a uniform, static field of magnetic induction B is determined in terms of the initial velocity of the center of mass, the initial angular velocity ω0, and the time. It is found that the component of the velocity of the center of mass in the direction of B is constant, whereas the components perpendicular to the field are damped exponentially; the angular velocity vector is always in the plane of B and the initial angular velocity vector ω0, but its magnitude is damped exponentially, with the component parallel to B being damped twice as rapidly as the component perpendicular to B. The motion in space of axes fixed in the sphere is determined in terms of solutions of the Weber equation.
Canonical Field Theory—A Prototype Example
Authors: Knight Bruce W.
Published: August 2005

The equations of a field may be put into a standard “Lagrangian” form from which several conservation laws follow directly. As an illustrative example, a string free to vibrate in two directions is investigated; this example clearly illustrates the outstanding features of the canonical theory, while avoiding the notational and physical complications encountered in most systems of practical interest. The conservation laws are interpreted for the string. The theory is further developed to express the field's behavior in terms of canonical coordinates and momenta. Quantum conditions are introduced, as in meson theory and quantum electrodynamics. It is shown that the mathematics of the “quantized string” is that of several charged particles occupying a set of energy states.
The “Best” Straight Line among the Points
Authors: Bacon Ralph Hoyt
Published: August 2005

The familiar method of fitting a straight line to a set of experimentally observed points by use of least squares, is reviewed, and variations of it briefly discussed. Then methods, apparently not so familiar to many physicists, for estimating the adequacy of the fit thus obtained, and for comparing the results of several such experiments, are explained. A few of the principles of mathematical statistics underlying these methods are given in the Appendix.
An Experiment in Teaching: Incomplete Symmetry of Physical Systems
Authors: Happ W. W.
Published: August 2005

A new approach to teaching a simple problem in optics is attempted by introducing concepts and ideas from recent developments in theoretical physics. The presentation is intended as an experiment in teaching at the junior college level with a view to stimulating the student's interest in mathematical physics.
The Concept of Radiation Measurements
Authors: Lovell Donald J.
Published: August 2005

Concepts are defined which are suitable for discussing all portions of the electromagnetic spectrum. The concept of “light” is limited to that portion of the spectrum called the visible region. The term radiation is employed as a more general concept. Similarly general and fundamental terms are used to illustrate techniques of teaching radiation without the confusion frequently connected with the psychophysical concepts of photometry.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 53. Photograph of H. A. Lorentz, H. Kamerlingh Onnes, Niels Bohr, and Paul Ehrenfest
Authors: Watson E. C.
Published: August 2005

The year 1953 marks the hundredth anniversary of the birth of two remarkable Dutch physicists, Hendrik Antoon Lorentz and Heiche Kamerlingh Onnes. The purpose of this article is to commemorate this anniversary by reproducing an interesting photograph of these two men, together with their great friends and fellow physicists, Niels Bohr and Paul Ehrenfest.
A Nonplanar Circuit with a Steady Current in a Uniform Magnetic Field
Authors: Amar Henri , Oberman Carl
Published: August 2005

It is shown that the forces on a nonplanar circuit with a steady current in a uniform magnetic field are the same as those on an equivalent plane circuit uniquely determined. The proof involves several remarks of mathematical interest.
Anharmonic Resonance
Authors: Jehle Herbert , Cahn Julius H.
Published: August 2005

The oscillations of a pair of classical oscillators which are synchronized because of anharmonic resonance can be calculated by the method of variation of constants. Two types of motion are studied: librational and nonlibrational—referring to oscillatory and progressive behavior, respectively, of the phase difference of the two oscillators. These motions are exemplified by the corresponding motion of a rod pendulum. Conditions for prolonged persistence of librational motion are discussed. This paper is essentially a review of some of E. W. Brown's papers on nonlinear resonance.
Some Thoughts on the Educational Process
Authors: Hutchisson Elmer
Published: August 2005

This paper analyzes the educational process, using graphical methods wherever possible. In its simplest aspect education is represented by a growth curve. If restricted to a single subject the curve is a two-dimensional one and may include both learning and forgetting. The mechanism of learning appears to be quite different for accumulative subject matter such as mathematics or physics from that in nonaccumulative fields such as political theory or business management. Combining the learning curves for several subjects one obtains an educational pattern which may be directly related to particular job requirements or to college admission requirements.
The Secondary School Textbook
Authors: Compton Charles A.
Published: August 2005

An analysis is made of existing textbooks in secondary school courses in physics. Particular attention is called to the illogical order, content, and over-popularization of material. These criticisms are supported by a detailed study of two important texts, and the question is raised whether these failings contribute to the shortage of young scientists.
A Course in Electromagnetic Radiation for Seniors
Authors: Cook C. Sharp
Published: August 2005

The course described replaces the optics course in the undergraduate curriculum. It is believed that the course described provides the student with a more interesting approach to the subject of optics, allows a better understanding of the relationship optics plays to the other fields of physics, and above all, gives a much better knowledge of the fundamental principles of the subject.
The Quantum Radiation of a Given Current
Authors: Koppe H.
Published: August 2005

A new treatment is given of the emission of light quanta by an electrical current. It works with the Heisenberg representation, and might be suitable for teaching purposes.
A Coordinated Program for Teachers of Chemistry and Physics
Authors: Rochow E. G.
Published: August 2005

While many programs are suggested for extending the instruction in physics for engineers and specialists, much remains to be done in adapting the introductory general courses to today's extended requirements. A program of reciprocity or coordination of subjects is suggested, particularly between elementary courses in chemistry and physics.
Physics for Students of Electrical Communication
Authors: Adler R. B.
Published: August 2005

The physics background of a student preparing for work in communication engineering is outlined and assesed. The parts which the postulational viewpoint from mathematics, its application to and abstractions from modern physics can play in his training are evaluated.
Physics for Non-Physics Majors in Chemical Engineering
Authors: Weber Harold C.
Published: August 2005

Some shortcomings of physics instruction from the standpoint of the chemical engineer are noted. Suggestions for improvement in the educational process include the discussion of approximate quantitative solutions to complex problems and the application of more imagination to the processes occurring.