bluuebunny/crossref_metadata_2025 huggingface dataset:
Baccalaureate Origins of Ph.D. Physicists
Authors: Siebring B. Richard , Schwahn Duane H.
Published: August 2005

Using the data gathered by the National Academy of Sciences about the baccalaureate origin of Ph.D. physicists for the periods 1936–1945, 1946–1950, and 1951–1955, the authors detected certain trends in the undergraduate training of Ph.D. physicists. It was found that the undergraduate training of physicists who earned doctorates during the years covered by this study was concentrated in a small proportion of this country's institutions of higher education. This concentration in the top institutions was found to be increasing.

The North Central states lost the lead in the undergraduate training of Ph.D. physicists to the Northeastern states. This is true both numerically and percentagewise. In terms of percentage contribution, the trend is toward the increasing influence of the technical schools (up 4.75%) rather than the colleges (down 5.2%) and universities (up 0.8%). The Ph.D. granting institutions have led the nongranting Ph.D. institutions over this time span and are increasing their percentage contribution. There is a slow trend from the privately controlled to publicly controlled institutions.
Resolution of the Clock Paradox
Authors: Builder Geoffrey
Published: August 2005

It is shown that the clock paradox of the restricted theory of relativity arose solely out of the elementary mistake of utilizing, in a single calculation, quantities expressed in the measures of two different reference systems.
Structure, Methods, and Objectives of the Required Freshman Calculus-Physics Course at Amherst College
Authors: Arons A. B.
Published: August 2005

A description is given of the Amherst freshman calculus-physics course with specific examples of test questions, term paper assignments, and laboratory instructions. A few quotations are given from student papers, and fairly detailed syllabi of the mathematics and physics work are included.
Collision Term in the Boltzmann Transport Equation
Authors: Desloge Edward A. , Matthysse Steven W.
Published: August 2005

The scattering probability W(v,v′), associated with particles of mass m interacting by means of hard elastic collisions with moving scatterers of mass M, is obtained in terms of the corresponding scattering probability associated with scattering from rigid elastic scatterers. The collision term in the Boltzmann transport equation can then be written in a form which is convenient for handling both equilibrium and transport phenomena. The conditions of equilibrium are discussed. The approximate collision term for a distribution function of the form f(v) = f0(v) + vxg(v( is derived, and the results applied to the problem of the conductivity to microwaves of a slightly ionized gas.
Simple Graphical Method of Drawing and Interpreting Parallel Planes through a Unit Crystal Cell for Any Given Set of Miller Indices
Authors: Savitsky George B.
Published: August 2005

It is shown that a graphical method can provide a rapid analysis of parallel planes in various crystal structures. This method can be used to answer questions regarding relative distances between planes and whether planes with a given set of Miller indices are equivalent, as well as to determine the relative populations of each type of atom in nonequivalent planes. This in turn enables one to make some immediate inferences about x-ray scattering intensities for various orders of reflection without recourse to complicated mathematical analysis. The method involves a construction of a projectional diagram in accordance with some simple rules, which are illustrated with reference to a cubic unit cell for CaF2, and then generalized to crystal structures of any other type.
Truth in Physics
Authors: Schmidt Paul F.
Published: August 2005

A number of different uses of the concept true are distinguished within physics in order to answer the questions: When is a physical law true? and When is a theory true? It is shown that a law cannot be tested as true or false independently of some theory. The concepts of true in physics are shown to be quite different from those of philosophy. The uses of true in physics make no reference to nature or the external world as is often held, nor do the changes in theories bring us progressively nearer to a correct picture of nature.
Apparatus Drawings Project Report Number 1. Balmer Series Spectrum Tube
Authors: Marcley Robert G.
Published: August 2005

A spectrum tube for the Balmer series of hydrogen that is simple to construct, reliable, and has a useful life in excess of 1500 hours is described. The intensity of the atomic spectrum of hydrogen is more than adequate for visual work with a grating replica or prism, and under proper conditions would be sufficient for photographic use. The molecular spectrum of hydrogen is of negligible intensity when the tube is properly filled. Full information is given on the construction and filling of the tube.
Certain Matters in Relation to the Restricted Theory of Relativity, with Special Reference to the Clock Paradox and the Paradox of the Identical Twins. I. Fundamentals
Authors: Swann W. F. G.
Published: August 2005

The paper first discusses the significance of the meaning of space-time coordinates as attached to “events” in the Lorentzian transformation. Restricted relativity involves two distinct parts: A—the invariance of the forms of the laws under the transformation: B—the hypothesis that similar experiments performed in relatively moving frames S and S′ give identical results. The test of A is a matter of pen and paper. B involves the hypothesis that the instruments are such that the actual measurements of space-time coordinates of events shall be related, for the two systems, by the transformation. Only by the postulation of a theory such as the quantum theory, but one relativistically invariant in sense A, can one understand the relationship between the instruments, whether the said instruments be constructed by independent observers in S and S′ from the material around them, or whether the observer in S′ acquires his instruments from S by setting them in motion. The second method of acquiring the instruments will not, in all cases, yield measurements related by the transformation. Thus, if we start with a system of isolated clocks which have been synchronized in S according to Einstein's principle, and if we transfer them to S′, their “rates” (in a suitably defined manner) may be expected to alter in accordance with the transformation. However, it will remain for the observer in S′ to synchronize the clocks in that new frame, having adjusted the time origin of one of them.
Influence of the Environment on the Wave Transmission of Energy: Resonance and Relaxation
Authors: Lindsay R. B.
Published: August 2005

This paper reviews the influence of the environment on the emission and absorption of radiation energy, both elastic and electromagnetic. Attention is called to the loading of wave sources which is independent of frequency. Of those influences which are frequency dependent, resonance and relaxation are the most important. These are compared and their similarities and differences noted. Numerous illustrations are presented.
Hula-Hoop: An Example of Heteroparametric Excitation
Authors: Caughey T. K.
Published: August 2005

This paper considers the parametric excitation of a pendulum swinging in a horizontal plane. It is shown that there exist a number of different limit cycle motions, one of which is a steady rotation about the point of support. This motion is associated with the mechanism whereby a Hula-Hoop may be kept in rotation by an oscillatory motion of the point of support. The stability and dependence of this type of motion on the initial conditions are analyzed in detail.
Thermodynamics of an Irreversible Quasi-Static Process
Authors: Thomsen John S.
Published: August 2005

Quasi-static processes are not reversible when sliding friction forces are present. An example is considered consisting of a cylinder containing a gas and equipped with a piston for which sliding friction forces are significant. It is assumed that the frictional force may be a function of temperature, displacement, and direction of motion. From measurements on the boundary of the system it is then possible to determine energy as a function of temperature and volume. However, force and entropy are not uniquely determined although thermodynamic considerations impose severe restrictions on the possible choice of these quantities. The generalized definition of entropy proposed by Bridgman is discussed in light of these conclusions. The possible analogy between this model and a perfectly plastic material is briefly discussed.
Search for a Fundamental Length in Microscopic Physics
Authors: McKinley William A.
Published: August 2005

This paper reviews some of the attempts to introduce into microscopic physics a constant of fundamental length. These theories aim to restrict the notion of localizability in the domain 10−13 cm or smaller in an effort to remove the well-known divergences which arise in modern field theory.
Elementary Electricity Experiment Involving Measurement and Synthesis
Authors: Smith Wesley R.
Published: August 2005

An elementary experiment designed to give the student a great deal of freedom in its conduct is described. The experiment develops the student's feeling for circuit behavior and introduces him to some nonlinear elements. It has been successfully tested in the laboratory of a large freshman physics course.
Apparatus Drawings Project. Report Number 2. Magnetic Field of a Circular Coil
Authors: Marcley Robert G.
Published: August 2005

The apparatus to be described will permit a quantitative investigation of the magnitude and direction of a 3-dimensional, cylindrically symmetrical B field, produced by a current-carrying coil. A 400-cps current through the coil produces a time-varying field which is measured with an accuracy of 2% by a moveable search coil, simple preamplifier, and ac voltmeter.
The Education of an American Scientist: H. A. Rowland, 1848–1901
Authors: Rezneck Samuel
Published: August 2005

The primary interest of this article lies in disclosing the circumstances and influences which combined to help, or hamper, the preparation of a young man for a career in science nearly a century ago. Rowland's particular case is, of course, highly individual and personal, but it also presents overtones reflecting the relevant conditions of the American social and educational scene in the last century. It illustrates how a young man, endowed with a natural talent, actuated, above all, by an early zeal for science, was able to acquire such formal training as was then available, but largely created his own opportunities for extracurricular experimentation and self-education. Good fortune and bold venturesomeness also played their part in enabling this obscure young student of physics to achieve early professional recognition through contact with Clerk Maxwell and Helmholtz, and to become, at twenty-seven, a member of the academic group assembled by President Gilman for a new venture in graduate education and research at the Johns Hopkins University.
Elementary Considerations on the Dynamics of Light Waves
Authors: Györgyi G.
Published: August 2005

An elementary treatment of the dynamical aspects of light refraction and Čerenkov radiation is given. Although some authors have given preference to the Minkowski energy momentum tensor in the interpretation of these effects, the treatment presented here shows that the rival theory of Abraham is fully capable of describing them correctly. A crucial point for the settlement of the old polemic concerning the energy momentum tensors of Abraham and of Minkowski, is recognized to be the existence of the Lorentz force acting on polarization currents. The Abraham energy momentum tensor yields an adequate expression containing this type of force, but the Minkowski one fails to describe this phenomenon.
Theory of Superconductivity
Authors: Cooper Leon N.
Published: August 2005

Some recent developments in the theory of superconductivity are discussed with emphasis on the underlying physical ideas. It is proposed that the electron-phonon interaction produces a strong preference for singlet zero momentum pairs in two-body correlations which can account for superconductivity and related phenomena.
Visiting Foreign Staff Project (V.F.S.P.) at Temple University
Authors: Offenbacher Elmer L.
Published: August 2005

We describe the National Science Foundation supported V.F.S.P. for institutes for secondary school teachers of science and mathematics, conducted for the first time in the summer of 1959. The need for the program stems both from the international nature of science itself and from the lag in our present secondary school science education. It is emphasized that lectures on recent advances in physics can be made more effective by organized programs such as the V.F.S.P. A briefing session is most important. Highlights of the visits' evaluation are followed by an introduction to the twelve papers constituting the heart of the project report. The fields of physics included are thermodynamics and molecular physics, low and high energy nuclear physics, thermonuclear physics, cosmic rays, three topics in solid state physics and metallurgical physics.
On the Education of Physicists in Three Foreign Countries
Authors: Goldfarb Albert M.
Published: August 2005

The basic systems of education in France, Argentina, and England are described, each followed by a discussion of the training of a future physicist or physics teacher in that country.
Some Aspects of Molecular Physics
Authors: Levelt J. M. H.
Published: August 2005

It is shown how the results of compressibility measurements in gases and liquids lead to the hypothesis of molecular interaction, and how details about this interaction may be obtained from the experimental data for the equation of state. The reasons for the molecular interaction are found in the laws of electrostatics and quantum mechanics.

The problems the molecular physicist is interested in are threefold. He wants to understand molecular interaction from first principles, he tries to get information about this interaction from a variety of experiments, and he seeks to understand a large group of experimental observations once the interaction of the molecules is known. For the solution of the second and third problem it is usually necessary to link the macroscopic observables to the microscopic molecular properties; although this has been possible in some instances, the general problem cannot be solved.
The Concepts of Classical Thermodynamics
Authors: Buchdahl H. A.
Published: August 2005

This paper, which is itself in the nature of an abstract, discusses how one can gain an understanding of the basic concepts of classical (phenomenological) thermodynamics, using virtually no mathematics at all, and without the introduction of the usual artifices such as abstract engines, cycles, perfect gases, and so on.
Thermonuclear Reactions
Authors: Thomson George P.
Published: August 2005

The possibility of extracting energy in a controlled manner from the nuclei of deuterium holds out the hope of a permanent solution of the problem of the supply of energy. It involves heating the gas to temperatures in the 100-million degree range. The outstanding difficulty is to prevent the heat escaping. Inevitable loss by radiation can be accepted. Loss by conduction must be greatly reduced. This means using magnetic fields.

Among the methods that have been tried to contain a plasma, three are: the pinch discharge in which a large current is passed through the rarified deuterium in a torus; containment by magnetic mirrors in which the diamagnetic character of the plasma is used to exclude it from regions of high magnetic field; Spitzer's stellerator in which gas is contained by re-entrant lines of force due to currents outside the vessel which holds it.

Difficulties arise in all cases; for the pinch discharge and to some extent the stellerator, these are due to some of the many forms of instability which can affect plasma in magnetic fields ; for the magnetic mirrors to the poor containment at relatively low temperatures and to difficulties of injection. No method has yet been successful, but all these are very hopeful.
A Look at the “Continental Classroom”
Authors: Randall Robert H.
Published: August 2005

This article comprises a set of three independent reviews of the 1958–1959 television presentation of a course in modern physics at about the college freshman level. There is a short introduction to the reviews by Robert H. Randall, Chairman of the Visual Aids Committee of the AAPT, pointing out the part played in the production by Dr. Harvey White, the chief lecturer, and also noting the occasional appearance of a number of prominent guest speakers. The joint sponsorship of the program is also described.

The three appraisals are supplied by Myron C. McCay of the University of Chattanooga, Truly C. Hardy of the City College, New York City, and Alan T. Wager of Arizona State University. In general, all three reviews pay tribute to the careful and effective handling of the subject matter by Dr. White and to the stimulation afforded by the presence of guest speakers. The lack of opportunity for discussion, inevitable with a television presentation, is stressed. A number of the guest speakers, in the view of the reviewers, spoke at too high a level. The course has apparently appealed to a large group of viewers well outside academic walls. In general, the venture is considered well worth the effort.
Testing for Physics Achievement
Authors: Ferris Frederick L.
Published: August 2005

Students are influenced strongly by tests, because the tests are to them the basis of rewards for their efforts. Because of this, it is essential that attempts to emphasize methods, as well as subject matter coverage, in physics courses must include the construction of tests that require the student to demonstrate his knowledge of process or method as well as knowledge. Examples of the way in which this has been done in connection with the tests that accompany the Physical Science Study Committee Course are included.
Method of Virtual Work for Some Problems in Physics
Authors: Srivastava Surendra Nath
Published: August 2005

The method of virtual work is applied to solve a number of problems in surface tension, and one problem in electrostatics. It is found that the solution is much simplified in many cases. The treatment is uniform in every case and is easily understandable.
Subcritical Reactor as a College Facility
Authors: Dietrich Frank S.
Published: August 2005

A subcritical assembly of natural uranium and ordinary water has been constructed at Haverford College as an educational instrument. Many of its parameters have been determined; their theoretical calculation and experimental measurement are discussed in the text.
Momentum and Conservation Laws in Newtonian and Canonical Formalisms
Authors: Frank William , Trigg George L.
Published: August 2005

A simple example is given to show how confusion can result from an uncritical transfer of concepts between Newtonian and canonical (Lagrangian or Hamiltonian) formalisms.
Atomic Term Symbols by Group Theory
Authors: Curl R. F. , Kilpatrick John E.
Published: August 2005

The problem of the terms that arise from a given electronic configuration is defined and then solved by elementary methods. The problem is then solved much more easily by the use of elementary group theory. Finally, a new closed solution is given by means of which the terms from even the most complicated electronic configurations may be rapidly enumerated. This new method has been used to compile a table of all terms from configurations up through nf14.
Note on a New Design for the Centripetal Force Apparatus
Authors: Chen Henry S. C.
Published: August 2005

A new design is given for the centripetal force apparatus such that any two of the three variables, mass, angular velocity, and distance, may be kept constant while the centripetal force is determined as a function of the third variable. Typical experimental results are given.
Apparatus Drawings Project. Report Number 5. Small Mass Spectrometer
Authors: Marcley Robert G.
Published: August 2005

A small-radius 180° mass spectrometer of a very simple type is described. The ion source is a tungsten filament coated with a salt of the material to be investigated. Using lithium-7, a magnetic field of 1000 gauss, and an accelerating potential of 100 v, a detector current of 10−11amp is obtained The resolving power is 33.
On Teaching the Philosophy of Physics
Authors: Seeger Raymond J.
Published: August 2005

Starting from the thesis that the philosophy of physics is taught in all courses of physics, including college general physics, the author urges teachers to become more articulate in their expressions in view of the ideological inferences being drawn by certain national groups. He illustrates his concern with three examples of modern physics, namely, relativity theory, concept of mass, and quantum mechanics. In each case he notes the Soviet interpretations, particularly as expounded by Professor A. F. Ioffé in his book Basic Concepts in Contemporary Physics.
Apparatus Drawings Project. Report Number 7. Versatile Mass Spectrometer
Authors: Marcley Robert G.
Published: August 2005

An extremely versatile mass spectrometer, suitable for an undergraduate laboratory and simple enough to be constructed by an average departmental shop, is described. The data obtained when using the potassium isotopes K41 and K39 indicate an instrument resolving power of 75. The auxiliary equipment required is conventional and inexpensive. The apparatus structure and construction techniques are described in detail.
Nuclear Models
Authors: van Wageningen Riek
Published: August 2005

A summary is given of the development of nuclear models, both for the description of structure and of scattering and reaction processes. The treatment is qualitative, and follows mainly the historical development. Models discussed are the liquid drop model, the potential well model for nuclear reaction processes, the compound nucleus model for nuclear reactions, and the shell model. Then a summary and comparison is made, followed by a brief sketch of the unified or collective model, which is a unification of the liquid drop and the shell model. Finally the nuclear optical model or complex potential well model is discussed.
Creative Thinking and Experimenting
Authors: Crane H. R.
Published: August 2005

The assumption is made that creative thinking, like playing tennis or bridge, is an activity rather than a phenomenon; that it can be cultivated through coaching and practice. An individual's ability at creative thought is not fixed in the same sense that the size of his feet are fixed. Therefore, the method which is often used for fostering it in the schools, namely, sorting out the creative thinkers and giving them special opportunities, meets only a part of the problem. A discussion of the creative process is given, with examples from the writings of Poincaré and others, followed by some words of advice which can be passed on to students.

Experimental science projects are discussed, with particular reference to those which are entered in science fairs. A sharp distinction is drawn between projects which are scientific investigations and those which are demonstrations. The former follows the pattern of question, hypothesis, experiment, modified hypothesis, etc. More new questions are raised than are answered, and the true flavor of research is tasted. The project which merely demonstrates a scientific process or principle may be a good teacher of facts, but it does not provide the experience of finding an answer by the scientific method. Some examples of the two types of projects are described.
Relativistic Theory of the Behavior of Clocks
Authors: Bradbury Ted Clay
Published: August 2005

The clock paradox is studied both from the point of view of special and general relativity. A solution for the case of a space ship moving in a straight line path with arbitrary acceleration is given in terms of special relativity. It is pointed out that an appeal to general relativity is not necessary as long as a single clock in the accelerator frame is considered, but that general relativistic considerations are necessary if two clocks separated by an appreciable distance are introduced into the accelerated frame. A solution for this case is given.
Simple Method of Determining the Thickness or the Refractive Index of Thin Films
Authors: Rao K. V. Krishna
Published: August 2005

This paper describes a simple method of determining the thickness or the refractive index of thin films using double-slit Fraunhofer diffraction fringes. To illustrate the method, the thickness of a gray photographic film and the refractive index of a cellulose acetate film have been determined.
Undergraduate Mass Spectrometer
Authors: Dewdney John W.
Published: August 2005

Described here is a simple static-field mass spectrometer which has had usefulness both as an undergraduate laboratory instrument and as a piece of demonstration apparatus. The design provides for the adjustment of such parameters as magnet position, slit widths and heights, and allows the use of different types of sources and detectors. Ion currents are large enough to be easily measured or displayed on an oscilloscope.
Electrical Conductivity and Thermoelectric Power in Ionic Crystals
Authors: Christy R. W.
Published: August 2005

Many of the most interesting mechanical and electrical properties of solids, especially at high temperatures or after radiation damage, depend on the presence of point defects—interstitials and vacancies—in the crystal lattice. Ionic crystals are especially suited for the study of these defects, because in them the defects are electrically charged. The ionic conductivity mechanism is reviewed, with reference to the information it yields about the properties of the defects. Recently, further information about the defects has been derived from the thermoelectric power (Seebeck effect), and these new developments are summarized.
Gravitational and Inertial Mass
Authors: Brown G. Burniston
Published: August 2005

One of the most astonishing features of the history of physics is the confusion which surrounds the definition of the key term in dynamics—mass, a confusion which has existed almost from the day that Newton defined it. Originally defined as a measure, i.e., a number, it became something which a body had, which could be measured. Mach considered the definition “unfortunate, ” Einstein “illusory,” and Sommerfeld called it a “mock definition.” Yet without it Newton could not have laid the foundations of dynamics, succeeding where Galileo failed. A careful examination of the problem shows, with very little doubt, that when Newton used the word density he meant what we now call relative density. His definition of mass is then unexceptionable. What is unfortunate is that he allowed himself to speak of mass with the common meaning as well as with the special meaning he had given it. Recently the terms gravitational and inertial mass have been coming into greater use, but the confusion has increased rather than diminished. The author's theory of inertia, which is in quantitative agreement with experiment, helps to lessen the confusion, both old and new.
Correlation Times, Line Widths, and Cross Relaxation of Spin Systems in Solids
Authors: Kaplan Jerome I.
Published: August 2005

A simple computational formulation is derived for calculating line widths of electron (or nuclear) spin resonance absorption in solids. The method is not limited to a Zeeman local field energy. It is further shown how, starting with time-dependent perturbation theory, cross-relaxation times are calculated. In both cases the results are expressed as the Fourier transform of a correlation function.
Physics in Auto Accidents
Authors: Barnes George
Published: August 2005

This article concerns a particular application of the fundamentals of physics with which most physicists have little contact. Some elementary physics commonly used by our law enforcement officers in the reconstruction of automobile accidents is reviewed. In particular, formulas for the determination of (a) vehicle speed through skid marks, (b) minimum speed for a vehicle skidding off-course while turning a corner, (c) minimum speed required to roll a vehicle over sideways, and (d) center of mass are discussed.
Robert Wichard Pohl: Oersted Medalist for 1959
Authors: Overbeck C. J.
Published: August 2005

Remarks made by the Chairman of the Committee on Awards for 1959 during the presentation ceremony of the Oersted Medal to Robert Wichard Pohl in recognition of his notable contributions to the teaching of physics.
Discovery of Interference by Thomas Young
Authors: Pohl Robert W.
Published: August 2005

Thomas Young contributed to philology and to the problems of vision, as well as to the understanding of wave motion and interference for which he is principally known. The steps by which he achieved understanding of the phenomena of interference, from his first work in 1801, through the publication of Course of Lectures on Natural Philosophy, and up to his development of the theory of the interferometer in 1817, are outlined.
Apparatus Drawings Project. Report Number 8. Driven Linear Mechanical Oscillator
Authors: Marcley Robert G.
Published: August 2005

A simple and robust apparatus for quantitative undergraduate investigations of forced damped harmonic motion is described. A variable frequency sinusoidal driving force is applied to a large mass suspended on a helical spring. The damping applied to the moving system may be adjusted. Phase measurements are easily made.
Some Remarks on Lattice Thermal Conductivity
Authors: MacDonald D. K. C.
Published: August 2005

The problem of lattice thermal conductivity (in an insulator) has been outstanding for many years. Debye and Peierls made fundamental contributions in relating finite thermal conductivity to anharmonic interactions between the normal modes of lattice vibration; detailed analysis and calculation, however, remains today a difficult problem. This paper presents a rather crude and elementary discussion of the problem for “classical” temperatures (T⋧θ) which yields a semiquantitative result in agreement with other workers. We are also able to make a rather direct estimate of the probable magnitude of the contribution to the thermal resistivity which arises from the quartic term in the lattice potential.
Observation of Length by a Single Observer
Authors: Weinstein Roy
Published: August 2005

One problem arising in teaching special relativity is the confusion in many texts of the thought experiments, used in developing the theory, with other simple laboratory operations. As an example we consider here the observation of length. The existence of the Lorentz-Fitzgerald contraction has led educators to conclude that one sees a contraction of a rapidly moving body. However, the act of seeing involves a single observer, while the observation of the Lorentz-Fitzgerald contraction requires at least two observers. It is shown here that the length seen by a single observer is not the usual contraction, and indeed, under certain circumstances, one sees a body considerably lengthened rather than contracted.
Electromagnetic Radiation from Extra-Terrestrial Sources
Authors: Friedman Herbert
Published: August 2005

Rocket astronomy has mapped the spectrum of the sun from the ground level cutoff at 3000 A down to x-ray wavelengths as short as 0.1 A. The x-ray emissions are strongly dependent on solar activity with greatly enhanced intensities accompanying solar flares. Photographs from rockets have revealed the disk distribution of ultraviolet emission. The first measurements of ultraviolet light of the night sky have discovered the existence of extended ultraviolet nebulosities surrounding hot stars and a bright diffuse glow of Lyman-α radiation scattered from neutral hydrogen in space.
On the Origins of the Special Theory of Relativity
Authors: Holton Gerald
Published: August 2005

Einstein's early work on relativity theory is found to be related to his other work at that time (e.g., in subject matter and style). In addition to this element of internal continuity one finds also—as a key to a new evaluation of the significance of Einstein's contribution—an external continuity with the classic, Newtonian tradition governing restrictions on permissible hypotheses. On the other hand, Einstein's work is shown to have been, in important respects, more independent of other contemporary work in this field than has recently been proposed.

These continuities and discontinuities are set forth to make the point that philosophical studies of scientific work should proceed on historically valid ground. Some guiding principles are indicated for dealing with conflicting source materials for such studies.
Optical Pumping
Authors: de Zafra Robert L.
Published: August 2005

A brief review is given of the basic concepts of optical pumping, followed by description of an optical pumping apparatus suitable for application to a number of experiments in an advanced undergraduate, or graduate laboratory.
Apparatus Drawings Project. Report Number 9. Simple Kinetic Theory Demonstration
Authors: Marcley Robert G.
Published: August 2005

The apparatus described in this article is a model for the simple kinetic theory of an ideal gas. It dramatically demonstrates the concept that the pressure a gas exerts on the walls of its container is due to the combined effect of the many individual impacts of the gas molecules on those walls. A massive moving system integrates the effect of many small equal impulses to produce a steady deflection whose magnitude is accurately predicated by simple theory.
Radiation Pressure on a Rapidly Moving Surface
Authors: Schlegel Richard
Published: August 2005

The radiation pressure is calculated for a surface which is moving in an electromagnetic radiation field that is isotropic to a rest observer. In the limit where the velocity of the surface is that of light, the pressure is found to reach a maximum value 2u, where u is the isotropic electromagnetic energy density for the observer at rest. The finite value comes with an integration over radiation incident at all angles, even though radiation from a source which is directly approaching the surface has infinite momentum when the surface velocity reaches the speed of light. Estimates of radiation pressure in interstellar space lead to the result that the energy expended by a space-traveling vehicle in moving against electromagnetic radiation, at any possible speed, would be negligible.
Use of Punched Cards for Personal Reference Files
Authors: Anderson R. A.
Published: August 2005

A brief discussion of the advantages of punched cards for personal filing systems is given, followed by a description of the system used by the author.
Misconception Concerning the Dynamics of the Impact Ball Apparatus
Authors: Chapman Seville
Published: August 2005

The impact ball apparatus, which usually consists of a straight row of balls of equal size touching each other, is used for demonstrating conservation of momentum. If the balls are perfectly elastic and there are more than two balls in the row, then if N balls are drawn aside and allowed to strike the remaining group, it is-just not true, as is often erroneously supposed, that N balls fly out from the other end of the row while the other balls remain at rest. The two principles of conservation of momentum and of energy are sufficient to determine the motion after impact of only two balls. If there are more than two, then the law of force between the balls (a 32 power law) must be invoked. The case for three equal masses with linear force laws is solved exactly and several consequences are discussed. Numerical solutions for the cases of three and four equal spheres are given. Calculations are found to agree with experimental data. When a single ball of velocity v0 impacts against two balls in contact at rest, the velocities after impact are −0.0710v0, +0.0765v0, and +0.9944v0, if the balls are elastic. Since the demonstration is always interesting and has many ramifications, it seems unnecessary to mislead students into believing that the velocities of the balls with relatively little motion arise because of inelasticity or misalignment, neither of which can explain the negative velocity. If the coefficient of restitution is much less than unity, then inelasticity masks the effects discussed here.
Virtual Binding and Its Relation to Resonance Scattering
Authors: Trigg George L.
Published: August 2005

A discussion of virtual binding and resonance scattering is presented in such a fashion as to make clear the relationship between them.
Deviations from Equipartition of Energy with Nonquadratic Hamiltonian
Authors: Peterlin Anton
Published: August 2005

If the Hamiltonian contains nonquadratic terms, the energy contribution per particle and degree of freedom deviates from 12kT (classical approximation). A very simple case which can be easily treated is that of a particle in a sinusoidal potential field. Energy, free energy, and molar heat are calculated as an example of the resulting deviations from equipartition.
Electromagnetic Waves in an Introductory Physics Course
Authors: Carr H. Y. , Sells R. L.
Published: August 2005

The properties of plane electromagnetic waves are derived without the use of calculus in a manner which provides a fundamental understanding of isolated waves far removed from their sources or any guiding conductors. The symmetrical relationship of the induced electric field to the induced magnetic field and the role of the displacement current are clearly demonstrated. Expressions for the velocity of the wave and the magnitudes and directions of the fields are derived. These results are developed directly from basic induced field concepts, thus avoiding the complications arising in the traditional transmission line approach which of necessity involves free charges and conduction currents.
Sophomore Laboratory Course in Modern Physics
Authors: Brody Selma B.
Published: August 2005

A new laboratory course in atomic physics using standard commercial apparatus, has been developed for students in their second year of physics. The experiments, apparatus sources, laboratory procedures, and results are briefly discussed.
Contribution of Thomas A. Edison to Thermionics
Authors: Johnson J. B.
Published: August 2005

A brief summary is given of the steps in the development of the thermionic vacuum tube. This leads back to the experiments of various people in the early 1880's, and particularly to the attempts by Thomas A. Edison to find the cause of the blackening of his newly developed incandescent lamps. Edison discovered during this work that substantial electric currents could flow between a hot carbon filament and another electrode across a high vacuum. Along with his contemporaries he wrongly ascribed the current to the flow of molecular ions rather than electrons. He, nevertheless, invented and built devices making use of these currents, the first applications of thermionics. The work received wide publicity at the time. Extracts from Edison's notebooks and other sources serve as illustrations.
Photographing and Projecting Crystal Patterns in Convergent Polarized Light
Authors: Burns Stephen H. , Jeppesen Myron A.
Published: August 2005

Procedures and inexpensive apparatus are described for photographing and projecting patterns formed by crystals in convergent polarized light. The methods are especially suitable for wide-angle patterns such as those formed by mica. Illustrations are given.
Simplification of Carathéodory's Treatment of Thermodynamics
Authors: Turner Louis A.
Published: August 2005

A simplified development of Carathéodory's thermodynamics, which obviates the principal mathematical complications of the original paper, is presented. A sketch of Carathéodory's treatment is given in an Appendix.
Error Analysis in the Introductory Physics Laboratory
Authors: Moreno Dario
Published: August 2005

Although most physics instructors agree that the analysis of error in a measurement is equally as important as the measurement itself, the matter is often neglected in the introductory laboratory. This neglect is frequently attributed to the belief that the relevant equations lie beyond the comprehension of the students. An elementary treatment of error is here presented in which it is shown that, at least in measurements involving simple functions, the propagation of error can be discussed using simple algebra. Two experiments are described as a basis for discussion.
Mechanical Equivalent of Heat Apparatus
Authors: McLeod John , Werbrouck Albert E.
Published: August 2005

A continuous flow-type mechanical equivalent of heat apparatus is described. It consists of two turbines immersed in water and rotated with respect to each other by an electric motor. Lucite housing facilitates observation of the energy conversion and provides good thermal insulation. In our elementary physics laboratories, most students obtain results within 2% of the accepted value.
Biophysics in the Medical Curriculum
Authors: Randall James E.
Published: August 2005

As biology becomes a more quantitative and theoretical science, concerned with mechanisms at both the molecular and macroscopic levels, the physician will need to be familiar with the analytical concepts and techniques of physics. An approach to meeting this need with efficiency is that of teaching a course devoted to the more physical and theoretical aspects of biology as part of the medical curriculum. This paper describes how one such course has been organized and taught for the past five years.
Real Fringes in the Sagnac and Michelson Interferometers
Authors: Zajac Alfred , Sadowski Henry , Licht Seymour
Published: August 2005

In describing the Michelson interferometer, it is usually stated that in order to observe fringes an extended source must be used. It has to be realized, however, that this requirement applies only to the formation of virtual fringes. Actually two distinct sets of fringes exist; virtual and real. Rarely, if ever, is attention brought to the existence of the latter type. The existence of the real fringes was first noted by the authors using the Sagnac interferometer, which is described in this paper. This little-known interferometer and the Michelson interferometer are both amplitude-splitting types. Real fringes were obtained for both a point source and an extended source while virtual fringes were, of course, only visible for an extended source. Similar sets of real fringes were also observed for the Michelson interferometer using either an extended or a point source. An analysis of the formulation of real fringes is presented.
Can Four-Year Colleges Prepare Physics Majors for Graduate Work in Physics?
Authors: Pake George E.
Published: August 2005

Some problems faced by four-year colleges trying to prepare physics majors are discussed, together with some proposals for their alleviation.
Students Method for Determining the Binding Energy of the Deuteron
Authors: Ortiz Eddie
Published: August 2005

A recording spectrometer model 1820 manufactured by Nuclear Chicago with a sodium iodide crystal scintillator, a neutron source, water, and paraffin are used to determine the binding energy of H2 by measuring the energy of the photons emitted when thermal neutrons are captured by H1.
Definition of the Perfect Gas
Authors: Landsberg P. T.
Published: August 2005

Usual definitions of the perfect gas are analyzed, and changes are proposed. The considerations advanced here lead to a view which, in its most extreme form, might run as follows: The ideal gas concept as used at present is unduly influenced by classical ideas, and out-of-date; but it can readily be modernized. The proposal is to define the ideal gas by the equation of state pv = gU, where g is a constant. The ideal classical gas is defined by the additional relation pv = NkT. These two equations lead to a system whose heat capacities Cv,Cp are independent of temperature, as normally required in elementary discussions. In other words, it is proposed that the ideal gas shall remain a generalization of the system for which pv = NkT and Cv and Cp are temperature independent, but it shall be defined by pv = gU rather than by pv = NkT.
Laws of Classical Motion: What's F? What's m? What's a?
Authors: Weinstock Robert
Published: August 2005

The basic definitions and laws of classical motion are systematically developed in a way which, when suitably amplified by the class-room teacher, can be made clearly understandable to any collection of reasonably intelligent beginning students of physics.
On the Tight Packing of Equal Spheres and Associated Problems in Flat N-Dimensional Space
Authors: Fahy Edward F.
Published: August 2005

As an exercise in the application of simple mathematics to a problem in N-dimensional geometry, the question of packing equal spheres together is examined. For the case of tight packing, it is found that the volume occupied per sphere is RN[(N + 1)2N]12 where R is the radius of the spheres. This is compared with the expression [π12NRN]/[Λ(1 + 12N)] which is the volume of a single sphere. The relation of the tight packing, as defined, to the closest possible packing is also discussed.
Measurement of Molecular Diameters and Average Velocities
Authors: Warner Robert E.
Published: August 2005

Pumping speed and gas viscosity measurements are described. These experiments permit a determination of average molecular velocities and molecular diameters to better than 10% accuracy. A vacuum pump, two McLeod gauges, and a filar micrometer microscope are required.
The Pierre S. du Pont Science Building, Swarthmore College
Authors: Dayton Irving E.
Published: August 2005

The Pierre S. du Pont Science Building at Swarthmore College was completed in the late fall of 1959 and houses the departments of physics, chemistry, and mathematics as well as the science library. The building comprises four distinct but interconnected units arranged around a central landscaped courtyard. The interior arrangement of the entire building is described and features of interest to physicists are pointed out. Particular attention is paid to the procedure followed in planning the building.
Physics Education in Poland
Authors: Piekara Arkadiusz
Published: August 2005

The basic system of education in Poland is described, followed by a discussion of the education in physics offered there.
Physics for the Biologist
Authors: Blüh Otto
Published: August 2005

The work of college physics teachers is to a great extent devoted to the teaching of service courses for nonphysics students, engineering students probably forming the largest group. Little provision is made for students in the biological sciences beyond the introductory physics course. With the growing recognition of the importance of physics in biology and medicine, and the advent of biophysics, it can be expected that physics departments will soon be called upon to organize advanced physics courses for biologists. This paper discusses the past and present situation, and outlines two physics courses for biologists offered at different levels: an intermediate course and a biophysics course. Out of these new physics service courses for the biology, premed, and medical students, and others, valuable experience will be gained about teaching programs for biophysicists.
Laboratory Performance Testing
Authors: Caughlan Georgeanne R. , Towe George C.
Published: August 2005

The nature of the laboratory performance testing program introduced at Montana State College in 1959 is described. Six original test problems are discussed. Analysis of the testing results reveals benefits which accrue to students and instructors such as improvement of regular laboratory work, a more realistic basis for grading, and the possibility of discovering instruction deficiencies.
Physical Nature of Shock Propagation
Authors: Band William , Duvall George E.
Published: August 2005

This paper gives an elementary discussion of the basic concepts required for an understanding of shock propagation. Simple derivations are presented of the Rankine-Hugoniot relations, Bethe's stability condition, Earnshaw's relation, and the structure of the shock front or shock profile.