bluuebunny/crossref_metadata_2025 huggingface dataset:
Electric Field of a Charge Moving in a Medium
Authors: Volkoff G. M.
Published: August 2005

The object of this paper is purely pedagogic—to clear up an apparent difficulty in applying Gauss' theorem to the classical electric field associated with a charge moving in an infinite homogeneous nondispersive medium with a constant velocity exceeding the velocity of propagation of light in the medium (conditions under which Cherenkov radiation is emitted). This is done by investigating the behavior of the electric field intensity not only inside the cone defining the region that can be reached by light signals from the charge but also on the cone.
Batting the Ball
Authors: Kirkpatrick Paul
Published: August 2005

The velocity vector of a ball struck by a bat is a stated function of the ball and bat velocities, bat orientation, and certain constants. In the light of the equations of the collision, the operation and the consequences of swinging the bat are analyzed, and the role of the constants is discussed.
Institutional Influences in the Graduate Training of Eminent Physicists
Authors: Siebring B. R.
Published: August 2005

American institutions were compared as doctorate sources of eminent physicists. Three criteria were used as recognitions of eminence of physics doctorate graduates. These were Fellowship in American Physical Society (1962), membership in the physics division of the National Academy of Science (1948–1960) and the Nobel Award.

It was found that the graduate training of the Fellows of American Physical Society (1962) was widely diffused over a large portion of the institutions granting doctorates in physics. However, a small group of institutions provided the doctorate training for the majority of the Fellows.

Universities were ranked by the percentage of (1930–49) physics doctorates who became Fellows of the American Physical Society in 1962. The top eight institutions were found to be Princeton, Carnegie, Rochester, Indiana, Harvard, Columbia, and Minnesota.

Doctorate granting institutions were also compared as employers of eminent physicists.
Outline of a Course in Plasma Physics
Authors:   Plasma Physics Study Group
Published: August 2005

This outline is part of an educational experiment initiated by the Commission on College Physics. The Commission has undertaken to highlight the need of college curriculum development in various areas of modern physics. One of these areas is the field of plasma physics. Difficulties in preparing a course in this particular field result from the fact that it has grown from fairly disparate areas of physics, including gas discharges, magnetohydrodynamics, and fusion physics. Synthesis of these various fields into a single course in plasma physics has not taken place spontaneously throughout the country and to look into this problem, the Commission set up a Plasma Physics Study Group to advise it as to what should be done. After considerable discussion, the Study Group decided to run a small working conference to prepare a course outline. This Working Group convened at MIT for a week during the summer of 1962 at which time the members of the group lectured to each other on those areas of their particular competence and at a level commensurate with the training of senior undergraduates in physics and electrical engineering. The notes prepared at that time, and subsequently edited in great detail, have been brought together in the form of the present outline.

The Study Group wanted to differentiate clearly between a finished textbook and an outline designed to guide teachers in preparing a course. This outline clearly bears the marks of this decision. It is not a finished production and it is not supposed to be. Rather than spend the large amount of time and labor necessary to produce a book, it is felt that a detailed outline, rapidly produced and circulated, would have more effect in persuading teachers to introduce plasma physics courses than might be the result of a carefully edited and maturely polished textbook. We hope that this type of effort is successful in stimulating a maximum number of teachers to use this outline material.

The next step in this experiment to introduce such a course with the maximum speed and efficiency is to await positive feedback by teachers who use this material in actual classroom teaching. The Commission would like to know not only about courses of this nature which are being taught, but would like further to receive criticisms and suggestions for improvement of this course outline. Please address your suggestions and criticisms to the Chairman of the Plasma Physics Study Group, Professor Sanborn C. Brown, Department of Physics, Massachusetts Institute of Technology, Cambridge 39, Massachusetts.
Parallel-Plate Plasma Problem
Authors: Hall Richard B.
Published: August 2005

The parallel-plate plasma problem is considered under the assumption of uniform density and a specular reflection boundary condition at the plates. The impedance of the device is derived for several different models of the plasma medium. The impedance of a hydromagnetic medium exhibits resonances whenever the plate separation is an odd multiple of a half-wave-length, as defined by the dispersion relation, while the Boltzmann equation yields similar results which include, however, the presence of losses in a collisionless plasma. The predicted resonances in the impedance can most likely be observed at high frequencies where only electron motion is important. The low-frequency resonances would be difficult to observe in gas-discharge plasmas because of the high collision frequencies and because the resonances occur at small wavelengths.
Stages in the Education of a Physicist: An Attempted Solution of a Pedagogical Problem
Authors: Douglass D. H. , Strandberg M. W. P.
Published: August 2005

In this paper, the stages in the development of a professional physicist are considered. One of the weak points of this process, the transition from the student stage to research apprenticeship, is considered in some detail. A teaching experiment that has been performed at MIT and was designed to bridge this gap is discussed. The results of this experiment lead us to propose this procedure as a partial solution to this particular problem.
Student Measurement of Fermi Energy by Positron Annihilation
Authors: McGervey John D.
Published: August 2005

The angular correlation of positron-annihilation radiation from a polycrystalline metal gives a value for the Fermi energy of the conduction electrons which is in excellent agreement with the free-electron gas model. With the setup to be described, in two hours of counting time, students in the advanced undergraduate laboratory can perform this measurement and obtain a value of the Fermi momentum which is accurate to within 3%.
Vertical Ballistic Pendulum Apparatus
Authors: Weltin Hans
Published: August 2005

This ballistics apparatus, assembled at practically no cost, eliminates the need of a spring gun and the nuisance of requiring sufficient space (as in the ballistic pendulum) to project a steel ball horizontally from the laboratory table. It also illustrates the behavior of a loaded spring in the gravitational field.
An Elementary Theoretical Approach to the Abbe Theory of Optical Image Formation
Authors: Gerrard Anthony
Published: August 2005

An approach to the Abbe theory using only fairly simple mathematics is presented. The approach was originally developed for use in training students preparing for the graduateship examination of the Institute of Physics. Regarding the image as a set of interference fringes, it is shown from considerations of coherence that (a) the fringes are localized in the true image plane, and (b) that the faithfulness with which the object is imaged improves as the number of diffraction orders passing through the system is increased.
Transport Properties of a Gas Mixture
Authors: Desloge Edward A.
Published: August 2005

The thermal and particle current densities of a gas mixture are derived by expanding the distribution functions in Laguerre polynomials and obtaining an approximate solution to the Boltzmann transport equation. The thermal diffusion factor is considered in detail. The techniques employed result in a number of simplifications of the usual derivations.
An Introduction to Dispersion Relations
Authors: Holbrow C. H. , Davidon W. C.
Published: August 2005

The concepts of causality, linearity, time symmetry, unitarity, and crossing symmetry and their relation to dispersion relations are discussed. Dispersion relations are applied to some simple electrical circuits in order to illustrate some of their properties and then a simple example is given of the use of dispersion relations for the analysis of the forward angle scattering of pions on protons.
Statistical Mechanics of a Quantum System of Hard Lines
Authors: Henderson Douglas
Published: August 2005

The energy levels of a one-dimensional quantum system of hard lines are obtained exactly and the resulting thermodynamic properties are evaluated by means of the grand partition function. No phase transitions occur. At high temperatures the thermodynamic properties of this system reduce to the well-known results for a classical system of hard lines.
The Microcanonical Ensemble
Authors: Tobolsky Arthur V.
Published: August 2005

In the usual development of quantum statistical mechanics the microcanonical ensemble is introduced in order to present the basic postulates of this subject with utmost clarity. However practical calculations of elementary problems using the microcanonical ensemble directly are seldom carried out. Either the method of the most probable distribution is introduced, or the canonical ensemble is introduced. Both of these methods require the development of further mathematical and physical concepts.

It is shown here that very elementary methods can be used to develop the thermodynamic properties of monatomic crystals and the “corrected” Boltzmann monatomic gas directly from the basic concepts of the microcanonical ensemble.

For more complex problems, it is shown that the microcanonical ensemble emphasizes the relation between basic concepts in statistical mechanics and certain unsolved problems in the theory of numbers.
Transient Stress Wave Problems
Authors: Rinehart John S.
Published: August 2005

The transient compressional stresses generated in solid bodies by impulsive loading provide an excellent vehicle for demonstrating to elementary students the physical character and implications of wave velocity, particle velocity, wave boundary conditions, and momentum partitioning. This paper suggests how some of these ideas can be presented.
On Certain “Ghost” Lines Observable with a Prism Spectrometer, and Their Use in Precision Refractometry
Authors: Moffat J. K. , Feather N.
Published: August 2005

When a prism with three polished faces is used on a spectrometer, because of partial internal reflection, light eventually emerges from all three faces of the prism. It is shown that, in general, there are only two directions of emergence from each face. From the face of incidence one of these directions is uniquely that of the externally reflected light. The two emergent beams from any face are unequally dispersed, and in certain circumstances one may be undispersed (one of the beams from the face of incidence is always of this character). In such circumstances the undispersed beam coincides in direction with each component of the dispersed beam when that component is at minimum deviation. This property provides an accurate method of adjustment for minimum deviation. When this method is used in practice, there are important advantages to be gained by heavily silvering two of the prism faces and making observations on the spectrum observed in a telescope directed towards the unsilvered face of incidence.
Note on the Use of the Gibbs Entropy Postulate in Statistical Mechanics
Authors: Salsburg Zevi W. , Willis Noel C.
Published: August 2005

In developing the ensemble theory of statistical mechanics, the thermodynamic temperature T, can be introduced in a direct manner avoiding the intermediate use of a Lagrange multiplier, if one adopts the Gibbs entropy postulate and uses a general criterion for thermodynamic equilibrium. This procedure is described in detail for both closed and open systems.
Mechanical Resonance (Experiment)
Authors: Salem Sema'an I. , Ault Earl R.
Published: August 2005

An experiment, based on the change in the velocity of the oscillating mass with applied frequency, has been designed and put to use. It is inexpensive and simple to build, and it may be valuable in an intermediate physics course.
Demonstration of Displacement Current
Authors: Meissner Hans
Published: August 2005

An apparatus is described in which the displacement current in a barium titanate capacitor forms the primary of a toroidal transformer with a Permalloy core surrounding the capacitor. The voltage output of the transformer increases with the square of the frequency. At f = 2kcps and a supply voltage of 50 V an output voltage of 50 mV is obtained.
Coherence and Correlation—Two Advanced Experiments in Optics
Authors: Bloor D.
Published: August 2005

Two “open-ended” optical experiments, intended to bridge the gap between teaching and research laboratories, are described briefly. They are designed to test the capabilities of all students while requiring only the simplest laboratory equipment.
Some Diagnostic Experiments to Accompany a Plasma-Physics Course
Authors: Burke B. E. , Crawford F. W.
Published: August 2005

There has been a considerable growth of interest in many aspects of plasma physics during recent years. This has been reflected in the introduction of new courses, or the expansion of old ones, in many colleges and universities to cater to the needs of students interested in this field. Laboratory experience constitutes an extremely valuable adjunct to teaching courses. There is, consequently, a considerable value in introducing experimental work wherever possible. This paper describes some laboratory experiments, requiring a minimum of expensive equipment, and which serve to introduce the student to useful diagnostic techniques which are founded on very basic models of plasma behavior. They have been tested in the laboratory and adopted for a laboratory instruction course given to graduate electrical engineers and physicists at Stanford University.
The Equation of Motion for Relativistic Particles and Systems with a Variable Rest Mass
Authors: Pomeranz Kalman B.
Published: August 2005

If the rest mass is constant the equation of motion may be presented in the form: force equals time rate of change in momentum. However, if the rest mass varies because there is an influx or or efflux of mass, the equation of motion may include additional terms to account for the momentum flux. These terms are derived by applying the impulse-momentum principal and the work-energy principle. The relativistic equation of motion gives the thrust as a function of the influx or efflux velocity, the rate of mass flow, and the Lorentz factor [1 − (v2/c2)]12 for the system.
Newton in the College Classroom
Authors: Bork Alfred M.
Published: August 2005

One segment of a course for nonscience majors using limited parts of Newton's Principia is described. The relevant source material is reviewed. The class studied in detail the proofs of some of the early theorems in the Principia, including the law of areas for central forces and the relation between forces and motion in conic sections. In spite of warnings in the literature, this was not too difficult; the students' background in geometry proved to be adequate to the task. It is suggested that it may be possible to follow a similar approach in high-school physics, or in the last several months of high-school geometry. In contrast with the usual course for nonscience majors and with most beginning courses in physics, Newton rapidly obtains important results. Using the Principia provides an introduction to the history of science in one detailed situation where some aspects of Newton's thought processes are examined.
Validity Conditions for the Kramers-Kronig Relations
Authors: Sharnoff Mark
Published: August 2005

The Kramers-Kronig relations are shown by elementary methods to be rigorously valid for linear, causal, stationary systems whose response functions obey simple conditions of boundedness.
Translation Project on Soviet Lecture Demonstrations in Physics
Authors: Robinson Howard A.
Published: August 2005

The history and background of a translation project on a series of eight volumes on lecture demonstrations in physics as given at the University of Moscow and published in the Soviet Union over the last ten years is given. An edited and condensed version of the translation is available on microfilm from the American Institute of Physics for five dollars.
Discovery of Nuclear Fission
Authors: Graetzer Hans G.
Published: August 2005

A complete translation of the original German article by Hahn and Strassmann on the radio-chemical evidence for fission of uranium has been made. This famous article was first published in January 1939, so that the year 1964 marks its 25th anniversary.
Magnetic Symmetry and “Forbidden” Effects
Authors: Birss R. R.
Published: August 2005

After a brief discussion of space inversion and time inversion, the distinction between magnetic and nonmagnetic crystal classes is illustrated by reference to cubic lattices. The appearance of “forbidden” effects in various crystal classes is discussed and recent experimental work on pyromagnetism, the magnetoelectric effect and piezomagnetism in antiferromagnetic materials is reviewed.
Consequences of Neutron-Proton Mass Difference in the Kinematics of Neutron-Proton Scattering
Authors: Ghatak Ajoy K.
Published: August 2005

A detailed study of the kinematics of neutron-proton, proton-neutron and neutron-neutron scattering (henceforth called n-p, p-n and n-n scattering, respectively) reveals a significant difference in the elastic differential cross section in laboratory directions corresponding to the near backward direction in the center of mass system. Based on the finite n-p mass difference, the n-p scattering cross section goes to ∞ at 86°59.5′, the p-n scattering shows a slight amount of backward scattering and the n-n scattering cross section equals zero for all laboratory angles greater than 90°. Most treatments of n-p scattering limit the discussion of the kinematics of the scattering process to a neutron-proton mass ratio to unity. It is of interest to consider the extent to which the actual difference in mass influences the angular distribution of the scattered particle. It is the purpose of this paper to discuss the consequences of the small, but non-negligible, n-p mass difference in the kinematics of scattering. Although it is not possible to obtain free neutrons at rest and hence p-n scattering cannot be observed in the laboratory, it, with n-n scattering is discussed here to get an idea as to what the kinematics of n-p scattering would have been if neutrons were lighter than protons and if the neutron mass were exactly equal to the proton mass.
An Axiomatic Approach to Dimensions in Physics
Authors: Parkinson Michael
Published: August 2005

A set of axioms and a formalism is presented for handling units and dimensions. Using the axioms, one form of the II theorem is proved simply and rigorously; also, two often debated questions are given definitive answers, both in the affirmative: (1) Are transcendental functions of a dimensional quantity legitimate? (2) Are the laws of physics always expressible in a form invariant under transformations of units?
A Library of Experiments
Authors: Oppenheimer Frank , Correll Malcolm
Published: August 2005

A new concept in physics laboratory instruction is described in which the experiments are available to the student in much the same fashion as books in a library. The general nature of the experiments is explained and the philosophy underlying the use of the laboratory for instruction is discussed.
The Moiré Phenomenon
Authors: Stecher Milton
Published: August 2005

A simple mathematical analysis using the shadow method is used to predict the shape, disposition, and spacing of moiré fringes produced by two parallel-line grids. The method is extended to grids of regularly spaced closed-nested-plane figures and then to repeated cell structures. Generalizing, it is shown that for any species of grid “moiré magnification” results. The linear and angular displacements of the fringes are related to the relative rotation and displacement of the grids to show the applicability of moiré fringes as a sensitive tool for positioning or for measuring very small displacements and rotations. A brief discussion is presented of the use of the phenomenon as a visual aid in the classroom.
Teaching Significant Figures
Authors: Logan Tracy H.
Published: August 2005

It is suggested that students would not be so careless about significant figures if they could actually see a demonstration of figures which are not significant. Such a demonstration is described, as is a simple teaching machine designed to give students facility in identifying insignificant figures in their calculations.
Inexpensive Physical Pendulum Experiment
Authors: Weltin Hans
Published: August 2005

With simple tools and with a minimum of manual dexterity, the cost of a physical pendulum experiment with a set of rings sold commerically for nearly $100, can be reduced to pennies by making use of bits of copper wire and squares cut principally from galvanized sheet metal scrap.
Modern Study of Solids
Authors: Patterson J. D.
Published: August 2005

This article attempts to present a modern viewpoint of solids from an elementary and yet fundamental point of view. The unifying concept used is that of the “particles” of solid-state physics. Electrons (with spin), holes, phonons, plasmons, and magnons are discussed. The interaction of these particles is discussed in experiments involving light absorption, x rays, magnetic resonance, the Mössbauer effect, neutron scattering, electron beams, charge and heat transport, and acoustic absorption.
Remarks on a Coordinate Transformation to an Accelerated Frame of Reference
Authors: Romain Jacques E.
Published: August 2005

A coordinate transformation from a one-dimensional inertial frame of reference to an accelerated one in empty space-time has recently been proposed by Lass. His derivation displays the remarkable feature that the motion of the accelerated frame relative to the inertial frame is fully determined by a set of assumptions, none of which implies any requirement regarding the individual motions of the different points of one frame relative to the other frame. This peculiarity is ascribed to the conjunction of several independent constraints imposed on the mutual relative motions of such points among themselves. The properties involved in Lass' transformation are analyzed, and their mutual implications are studied. It is found that one property (namely, that the speed of light with respect to the noninertial frame, at each point of this frame and in both directions, is time-independent) has a special status. A comment is made regarding the extension of the transformation to a three-dimensional system.
Anniversaries in 1964 of Interest to Physicists
Authors: Barr E. Scott
Published: August 2005

During the year 1964 there are major anniversaries of the birth or death of eleven men whose accomplishments and influence have been of importance to the development of physics. They are: Joseph Sweetman Ames; Anders Jonas Ångström; Galileo Galilei; Julius Robert von Mayer; Hermann Walther Nernst; Nicolaus de Cusa; Denis Papin; Benjamin Thompson, Count Rumford; Benjamin Silliman, Sr.; Wilhelm C. W. O. F. F. Wien; and John Winthrop. Brief accounts of their achievements and lives are given here.
Theory of the Air-Supported Puck
Authors: Whitney W. M.
Published: August 2005

An approximate solution of the Navier-Stokes equation is given for incompressible flow through the thin annular gap beneath an air-supported puck. Expressions are derived which relate the pressure in the air film to the weight and dimensions of the puck, the thickness of the film to the total air flow, and the retarding force to the speed of a moving puck.
Magnetism in One-Dimensional Systems—The Heisenberg Model for Infinite Spin
Authors: Fisher Michael E.
Published: August 2005

It is observed that the free-energy, susceptibility, and correlation functions for a linear chain of N spins with nearest-neighbor isotropic Heisenberg coupling can be calculated explicitly in the (classical) limit of infinite spin. The results are compared briefly with those for Ising and Heisenberg chains of spin 12.
Trapping of a Charged Particle in a Static Magnetic Field
Authors: Baker Don A.
Published: August 2005

Contrary to a rather widespread belief, the Newton-Lorentz equation of motion mdv/dt  = qv × B does not exclude orbit solutions which represent the trapping of a charged particle which is externally injected into a region of time-independent magnetic field. Specific examples of such orbits are demonstrated. Theorems of Liouville and Poincaré are used to clarify the nature of the restrictions which classical mechanics imposes upon the injection and trapping of charged particles in a static magnetic field.
A Magnetic Resonance Experiment for the Undergraduate Laboratory
Authors: Limon Peter J. , Webb Robert H.
Published: August 2005

A magnetic resonance experiment is proposed which is suitable for a junior or senior undergraduate laboratory course. By use of a six-level spin system and simple detection equipment, a number of concepts may be emphasized which are unavailable to the usual NMR or ESR experiment, and the physical content, as distinct from instrumentation, may be emphasized.
Less May Be More
Authors: Morrison Philip
Published: August 2005

Physics, like all of science, is not merely analytic. Its power of analysis is best demonstrated in its synthetic successes, the design of new questions, new experiments, even new devices. For the students whom we do not now really reach, including a large fraction of all elementary teachers, a very large proportion of women, indeed, the bulk of the college population, we need a new emphasis. It is valuable to vary the style and mood, to break with the Euclidean model at least sometimes, to employ humor, playfulness, invention; above all, to go beyond mere verbal and formula-learning. It is to be expected that the visual and graphic arts, broadly viewed, might make a merger with laboratory science at an introductory level which would genuinely change the audience we can hope to involve. The free use of simple construction materials, accompanied by some analysis of a mechanical and geometrical kind, might begin a course of rich variety which would present circuits and probability, group theory and astronomy, optics, mechanics, radioactivity, even biochemistry, as lab experience and initial analysis. Aesthetic participation and wide context appear more valuable than the necessarily didactic route to the full modern world view of the physicist. Less may be more. Some topics are more fully sketched.
Remedial Programs
Authors: Crane H. R.
Published: August 2005

Students in introductory physics courses often have easily diagnosed weaknesses in their ability to use basic mathematical tools. Experience with remedial material in the form of linearly programed reviews has shown it to be valuable, both on an individual and a mass basis, in alleviating these weaknesses. The philosophy of construction and use of such materials is discussed, and a sample program presented. Four remedial programs—in geometry, trigonometry, vector addition, and exponents—have been prepared and are available for trial use in limited quantities. Suggestions for additional topics are both made and solicited.
Walter Christian Michels: Oersted Medalist for 1963
Authors: Verbrugge Frank
Published: August 2005

Remarks made by the Chairman of the Committee on Awards for 1964 during the presentation ceremony of the Oersted Medal to Walter Christian Michels in recognition of his notable contributions to the teaching of physics.
Sophomore-Laboratory Experiment on the Viscosity of Air
Authors: Oppenheimer Frank
Published: August 2005

We present the design of a simple rotating-disk viscometer that can be actuated while under a bell-jar to measure the viscosity of a gas as a function of pressure. The instrument is designed to provide an interesting application of the kinetic theory of gasses for an introductory physics laboratory.
The WKB Method in Three Dimensions
Authors: Critchfield Charles L.
Published: August 2005

The WKB method of solution to Schrödinger's equation is usually applied individually to partial waves of definite angular momentum, i.e., in one dimension. However, the partial differential equation may be solved directly, by this method, and the first two terms are derived for the solution to scattering by a central potential. The resulting cross section is the same as in classical theory.
Relation between Generalized Foldy-Wouthuysen and Lorentz Transformations
Authors: Sesma J. , Biel J. , Garrido L. M.
Published: August 2005

A relation between the generalized Foldy-Wouthuysen, presented in a preceding paper, and the special Lorentz transformations is shown.
Resource Letter MOP-1 on Masers (Microwave through Optical) and on Optical Pumping
Authors: Moos H. W.
Published: August 2005

Prepared at the request of the AAPT Committee on Resource Letters; supported by a grant from the National Science Foundation.

This is one of a series of Resource Letters on different topics, intended to guide college physicists to some of the literature and other teaching aids that may help them improve course contents in specified fields of physics. No Resource Letter is meant to be exhaustive and complete; in time there may be more than one letter on some of the main subjects of interest. Comments and suggestions concerning the content and arrangement of letters as well as suggestions for future topics will be welcomed. Please send such communications to Professor Arnold Arons, Chairman Resource Letter Committee, Department of Physics, Amherst College, Amherst, Massachusetts.

Notation: The letter E after an item number indicates elementary level, useful principally for freshman liberal arts through sophomore physics courses; the letter I indicates intermediate (junior, senior) level; and the letter A indicates advanced material principally suited for senior, graduate study. An asterisk (*) indicates items particularly recommended for introductory study.

Additional copies: Available from American Institute of Physics, 335 East 45 Street, New York, New York 10017. When ordering, request Resource Letter MOP-1 and enclose a stamped return envelope. A small booklet containing reprints of some of the fundamental references will soon be available for purchase from the American Institute of Physics.
A Note on the Teaching of Gyroscopic Precession
Authors: Larmore Lewis
Published: August 2005

The concept of gyroscopic precession is frequently one of the most difficult encountered by beginning physics students. A new method of presenting this material is suggested which follows logically from the usual studies of uniformly accelerated linear and angular motions.
Precision Measurement of Period vs Amplitude for a Pendulum
Authors: Smith Malcolm K.
Published: August 2005

The dependence of the period of a simple pendulum upon the amplitude of its swing is demonstrated with the aid of a precise timing system consisting of a photocell that triggers a frequency counter functioning as a clock. The period is measured to a few parts in 105. The quadratic dependence of period on amplitude is clearly shown.
The Zeeman Effect in Molecules
Authors: Quade C. Richard
Published: August 2005

The dynamics of an asymmetric top molecule in an external magnetic field is developed. The resulting classical Hamiltonian is in a form which is suitable for the transition to quantum mechanics. The formulation utilizes a velocity-dependent potential to introduce the magnetic field. Particular care is taken to establish the proper relation between the conjugate coordinates and the components of total angular momentum.
Nonsimultaneous Measurement of the Coordinates Used to Obtain the Length of a Uniformly Moving Body
Authors: Durbin Kenneth A.
Published: August 2005

In many textbooks concerned with relative measurements in the special theory of relativity, the length of a uniformly moving rigid body is calculated on the basis that the coordinates of the two ends of the body are to be determined simultaneously. The present paper shows that, for this simple problem, it is both possible and physically more meaningful to make such a determination nonsimultaneously by taking into account the fact that light signals require a finite time to propagate. The basic idea of nonsimultaneity is extended to the calculation of the Doppler shift of light frequency, giving the usual relativistic result.
Rutherford and his Alpha Particles
Authors: Osgood Thomas H. , Hirst H. Sim
Published: August 2005

The authors give some personal recollections of their participation in the experiments of Rutherford and Chadwick on the disintegration of light elements by impact of alpha particles in the 1920's.
General Solutions of the Hamilton-Jacobi Equation
Authors: Epstein Saul T.
Published: August 2005

The importance of finding general solutions to the Hamilton-Jacobi equation is emphasized. The procedure for doing so is presented together with examples of its use.
Oscillations in Single and Colliding Plasmas
Authors: Mirman R.
Published: August 2005

The study of a few idealizations of plasma oscillations, such as the electrostatic, electromagnetic, and hydromagnetic modes illustrate the behavior of vibrations in a plasma. The dispersion relations for each type are derived here and their significance is discussed. Further consideration is given to electrostatic modes of interacting streams with a brief mention of instability growth and decay.
Interferometric Observation of Flat Surfaces and Multiple-Beam Edser-Butler Bands
Authors: Keck Donald B. , Hause C. D.
Published: August 2005

It is suggested that two experiments in intermediate optics be augmented by the introduction of Herriott's multiple-beam multiple-wavelength technique. In the first, a simple method for demonstrating the use of the technique in contouring optical surfaces is given. The second uses a similar technique to produce multiple Edser-Butler bands. A description of the apparatus for obtaining multiple Edser-Butler bands is given and the use of these multiple bands to determine the thickness of a thin etalon is illustrated.
Quantum Scattering Theory in One Dimension
Authors: Eberly Joseph H.
Published: August 2005

A phase-shift analysis of quantum mechanical scattering problems in one dimension is developed. Many of the techniques and results of three dimensions remain even in one dimension, while the discussion is vastly simplified, and thus accessible to the student much earlier, due to the absence of special functions (in particular, Bessel and Legendre functions) with their complicated asymptotic formulas and orthogonality relations. A “partial wave” analysis leads to the familiar relation fl∼eiδl sinδl between the scattering amplitude in the lth partial wave and the phase shift δl. The optical theorem is evident as an immediate consequence of the conservation of probability. The method is applied to an analysis of the well-known square-well scattering resonances.
Tube Method for Measuring the Velocity of Sound in Gases
Authors: Romer I. Carl , Koentop Preston E.
Published: August 2005

A technique for measuring the velocity of sound in gases confined in tubes is described. The basic apparatus first proposed by F. A. Angona [J. Acoust. Soc. Am. 25, No. 6, 1111–15 (1953)] mainly for measurement of tube attenuation coefficients was adapted for this purpose. The method involves locating two positions of identical phase along a free progressive wave. Such a wave is made possible by an absorbing termination. The value obtained for the velocity of sound in high purity nitrogen gas at 21.1 C (70 F) and atmospheric pressure is 349.78 m/sec as compared to a calculated value of 349.80 m/sec.
Rate of Surface-Strain Tensor
Authors: Dishington R. H.
Published: August 2005

Although some work exists relating to the kinematics of fluid surfaces, no development parallel to that for linear and volume elements exists. It is shown, in this paper, that a rate of surface-strain tensor can be defined that has the same relationship to rate of surface extension that the rate of strain tensor has to rate of linear extension. Under some circumstances, this new tensor and a more useful form of the surface transport theorem derived from it, provide an improvement in the physical interpretation of equations of fluid motion. Practical applications have been found in the field of non-Newtonian flow, and hopefully will be found in other fields such as the theory of surface waves and meteorology.
Temperature and Pressure Dependence of the Viscosity of Gases
Authors: Cronin David J.
Published: August 2005

This paper describes a method for making absolute measurements of the viscosity of gases, using timed flow through a capillary. Air, nitrogen, carbon dioxide, argon, helium, and hydrogen were studied at temperatures between 77° and 295°K. Nitrogen was also measured at pressures from 15 to 130 cm of mercury. Accuracy of 2% or 3% is obtained with relatively simple apparatus. The experiment is suitable for an undergraduate laboratory.
Method for Proving that a Given Response is Optimum
Authors: Kunz K. S.
Published: August 2005

A novel method is developed for proving that a particular forcing function f(t), selected from a set of permissible functions, returns a mechanical system to a required state in the minimum time. This method makes use of the moments of the forcing function f(t), or of similar integrals involving f(t), and is illustrated by an application to two mechanical problems. In the first, a free mass is to be positioned in the minimum time using an upper bound on the magnitude of the force. In the second, a system with a restoring torque is to be positioned in the minimum time using an applied torque with an upper bound on its rate of change. The method for proving the optimum nature of the derived forcing functions is thought to be of interest in other fields.
Ways to Improve Undergraduate-Laboratory Report Writing
Authors: Stumpf F. B.
Published: August 2005

Several ways to improve instruction in undergraduate-laboratory report writing are presented. These involve increasing the student's awareness of the importance of good written expression, showing him examples of good writing, and giving him mature criticism on his reports. The concern is expressed that more attention must be given to this instruction in the future or the quality of writing will decrease due to less personal contact with senior staff.
Thermodynamic Fluctuations
Authors: Callen Herbert
Published: August 2005

The general theory of thermodynamic fluctuations in canonical ensembles is derived in a simple and exact form in terms of the semiinvariants (or “cumulants”) of the distribution.
Demonstration Microwave Interferometers
Authors: Andrews C. L.
Published: August 2005

By use of wavelengths of 4 cm, complete demonstrations in microwave optics were mounted on boards the size of a sheet of writing paper. For lecture demonstrations they were constructed on Plexiglass plates above the 10-in.-sq. glass platform of an overhead projector. Detailed descriptions of the constructions were made for Lloyd's mirror, Michelson's interferometer and a grid-detection interferometer.
Problem of a Spin in a Time-Dependent Magnetic Field
Authors: Montgomery David , Ruijgrok Th. W.
Published: August 2005

The long-standing disagreement between the exact and perturbation solutions for the problem of a spin one-half particle in crossed, time-dependent, magnetic fields is resolved. The resolution is achieved by adapting the perturbation methods given by Krylov, Bogoliubov, and Mitropolskii for classical systems.
An Invariance Property of the Free Electromagnetic Field
Authors: Calkin M. G.
Published: August 2005

In the absence of charges and currents, Maxwell's equations are invariant under the transformation E′ = E cosθ+B sinθ, B′ = −E sinθ+B cosθ. Using Noether's theorem, we show that the corresponding conserved quantity is proportional to the difference in the number of right and left circularly polarized photons in the field.
Cherenkov Radiation, “Physical” and “Unphysical,” and its Relation to Radiation from an Accelerated Electron
Authors: Lawson J. D.
Published: August 2005

The δ-function of current which represents an electron traveling in a straight line is Fourier analyzed into a spectrum of infinite linear harmonic currents, having spectral distributions both in frequency and phase velocity. The radiation (and induction) fields associated with these currents are associated either with Cherenkov radiation or with acceleration or deceleration radiation (“bremsstrahlung” in the literal sense) according to whether the velocity of the electron exceeds or is less than that of light in the medium. The analysis of the two situations is identical; indeed, the two types of radiation cannot, in general, be sharply distinguished.
An Elementary Approach to Sublimation of a Multicomponent Solid
Authors: Caulfield H. J.
Published: August 2005

A simple discussion of the pressure-temperature relation during sublimation of a multi-component solid is presented. The assumptions and limitations are shown explicitly, and experimental verification of the applicability of this analysis is discussed.
Foundations of Special Relativity and the Shape of the Big Dipper
Authors: Komar Arthur
Published: August 2005

The foundations of the special theory of relativity are examined in a new form which is more in keeping with the space-time symmetry of the resulting theory, and which employs those concepts which are most directly related to actual observation. The transformation group to which one is immediately led is the conformal mappings of the two-sphere, which, as is well known, is isomorphic to the homogeneous improper orthochronous Lorentz group. In order to obtain extensions to the Poincare group and/or the Einstein group of general relativity, additional assumptions are required.
Experimental Study of Multiple-Choice and Essay Tests. I
Authors: Kruglak Haym
Published: August 2005

Two teacher-made tests dealing with physics terminology were constructed and administered to four groups of students in two general physics courses. Each test consisted of an essay and multiple-choice part. Test reliabilities tended to be higher for the essay parts. The grader reliabilities of the essay parts were high, but there were significant differences between the mean grades by two instructors. The correlation coefficients between the test scores and total course achievement were moderately high. The correlations tended to be higher for the multiple-choice tests. It was tentatively concluded that (1) multiple-choice and essay tests on definitions had low to moderate correlations with each other and (2) multiple-choice tests of physics definitions were fair to good predictors of achievement in general college physics.
Compton-Scattering Experiment using Low-Activity Gamma-Ray Sources
Authors: Chow R. H. , Herold J. S.
Published: August 2005

An experiment on Compton scattering of gamma rays using low-activity gamma-ray sources usually requires a multichannel pulse-height analyzer if the experiment is to be completed within a reasonable length of time. Herein is described a method not requiring such an analyzer, yet permitting the use of a radioactive source of such low activity as to be available license free. The experiment is within the scope of colleges only modestly equipped. The technique is not restricted to Compton scattering only, but may be used generally for nuclear spectroscopy studies.
New Physical Sciences Lecture Hall
Authors: White Harvey E.
Published: August 2005

A new and unique type of science lecture hall has been constructed on the Berkeley Campus of the University of California. Known as the “Physical Sciences Lecture Hall” this facility seating 550 students incorporates a large rotating stage and closed-circuit television. The rotating stage 40 ft in diameter has three complete lecture-room fronts, in the form of an equilateral triangle, and each has all laboratory utilities permanently connected to all lecture tables. The stage permits full demonstration lectures to be given every hour of the day. Sixteen TV picture tubes, suspended by hoists from the ceiling, and two vidicon TV cameras, one operated by the instructor and the other by remote control, make all lecture room demonstrations and activities visible to everyone.
Sources for Half-Life Experiments
Authors: Taylor Julius H. , West Andrea P.
Published: August 2005

Student results of several laboratory experiments of half-lives of one-, two-, and three-component systems are analyzed. The work is presented for its pedagogical value to teachers of radioisotope techniques.
Ejection of Atoms from Metallic Single Crystals
Authors: Cunningham R. L. , Ng-Yelim Joyce
Published: August 2005

The unique characteristics of experimental data obtained from the directional ejection of atoms from metallic single crystals subjected to ion bombardment are discussed. The advantages, for instructional purposes, are outlined. Simple experiments are described that are designed to give the beginner in crystallography a working familiarity with (1) crystal directions, (2) techniques for orientation determinations, and (3) anisotropic characteristics of crystals. All experiments described may be performed with simple and inexpensive equipment.
Dialogue on Statements and Mis-Statements About Energy
Authors: Armstrong H. L.
Published: August 2005

Some statements commonly seen about energy and its conservation are criticized as being loose, misleading, and useless. In particular, it is argued that any discussion which seems to put energy into the category of substance must be suspected.
Books Most Often Recommended by Textbook Writers
Authors: Lufburrow Robert A.
Published: August 2005

Sixteen books are identified as those most often recommended as supplementary reading in introductory physics textbooks.
Apparatus for Measuring the Specific Heat of a Gas
Authors: Livesey D. L.
Published: August 2005

A simple type of apparatus has been developed for measuring the specific heat of a gas at constant volume with an accuracy of about 10%. A large capacitance is used to supply a known amount of energy to a known amount of gas and the momentary rise of the gas pressure is recorded. With a suitable choice of time constant the results are highly reproducible and the calculated specific heats of air and argon are close to accepted values.
Evidence Against Emission Theories
Authors: Fox J. G.
Published: August 2005

The Ritz theory of electromagnetism and optics is criticized in relation to the experimental evidence after the introduction of a simple and natural modification of the hypothesis concerning the velocity of radiation scattered by the electrons of a medium. It is argued that the theory is then in harmony with the electron theory of dispersion, accounts satisfactorily for aberration, the first-order Doppler effect from moving sources and interferometer experiments on binary stars. There is no evidence from binary stars which contradicts it. It is compatible with the second-order Doppler effect and possibly the Fizeau experiment since arguments are advanced which indicate that these phenomena depend essentially on the momentum and energy of radiation. Other phenomena are discussed. It is concluded that the best evidence against the theory comes from experiments on the lifetimes of fast mesons and the velocity of γ rays and light from moving sources. The justifications for the discussion are the desirability of having the experimental base of an important part of physics be as rigorous as possible, and the hope that it sharpens our understanding of existing evidence for special relativity and stimulates new and different experiments.