bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Recent Past of Physics
Authors: Holton Gerald
Published: August 2005

A brief account of current work in the history of modern physics is given to indicate that the interest of physicists in this field is rising, and that they are beginning to participate in greater numbers. The analyses by A. H. Compton, G. P. Thomson, C. D. Anderson, and W. F. G. Swann of their own early work are used to show some persistent characteristics of developing scientific work.
The History of Cosmic Rays
Authors: Swann W. F. G.
Published: August 2005

The history of developments in the cosmic-ray field is traced back to the time when there was uncertainty about the origin of ionization in closed vessels. We then pass through the period when, through the high-altitude experiments of Victor F. Hess, we were forced to admit the existence of a radiation coming from outside our atmsophere. The controversy as to whether the rays are photons or charged particles is sketched and leads through the results of geomagnetic effects to the conclusion that the primaries are positively charged particles, mostly hydrogen, but that in addition there is about 15% of helium, and representatives of probably all elements are to be found in amounts diminishing with increase of atomic number. The effect on the detailed study of cosmic ray phenomena (as observed in the atmosphere) of the discovery of the mesotron and the positron is traced, as is the part played by such theoretical discoveries as “pair production.” Brief reference is made to “large showers,” and the paper concludes with a brief summary of our knowledge of the origin of the primary cosmic radiation and of the part played by “island magnetic fields” existing in our galaxy and even in our solar system.
Some Applications of Schwinger's Principle
Authors: Chambers LL. G.
Published: August 2005

Formulas are derived using Schwinger's variational principle for capacity, potential coefficients, and inductance.
Relativity and Parallel Wires
Authors: Webster David L.
Published: August 2005

Special relativity gives simple answers to the freshmen's persistent questions, “Why should like currents attract, when like charges repel?,” and, “Why should the speed of light come into the laws of parallel-wire forces?” These answers are derived here in two ways: first, to prove them logically sound, from the Lorentz transformations, with v the drift velocity of the carriers; then by essentially equivalent calculations that have been found intelligible and interesting to freshmen.
Apparatus Drawings Project. Report Number 21. Ionization Chamber
Authors: Marcley Robert G.
Published: August 2005

A simple parallel-plate ionization chamber of the integrating type is described. It was specifically designed for undergraduate investigations of the effects of ionizing radiation on a gas under the influence of a relatively small electric field. A simple gas handling system permits operating the chamber with air or several pure gases at any pressure from a few mm Hg up to several atm γ rays easily penetrate the chamber envelope, while collimated beams of α, β, and soft x radiation can be passed through a thin window into the sensitive region between the rectangular plates. Ancillary apparatus required for experiments consists of 0–100 v potential source, an electrometer capable of measuring a current of 10−13 amp full scale, and a small mechanical vacuum pump. Construction details are given.
The Mössbauer Effect
Authors: Lustig Harry
Published: August 2005

This article reviews the recent discovery and several important applications of recoilless gamma-ray fluorescence. Its main purpose is to give to nonspecialists a self-contained introduction to this currently very lively field of research. The importance of the fluorescence technique and its limitations, before Mössbauer's discovery, are discussed. Mössbauer's pioneering experiments are briefly described and Lipkin's simple theoretical explanation of recoilless gamma-ray emission is presented. From among the large number of recent experiments which make use of the Mössbauer effect, two groups are selected for discussion. The first is concerned with the discovery of nuclear and magnetic properties of iron-57; the other with a test of the principle of equivalence in general relativity, by a measurement of the gravitational shift in the frequency of radiation.
Apparatus Drawings Project. Report Number 12. Hall Effect Magnet
Authors: Marcley Robert G.
Published: August 2005

A small electromagnet designed for use with an indium-antimonide Hall effect device is described. A coil current of 2.3 amp produces a field of 3 kgauss across a 0.56-cm gap. The field is uniform to within 10% over an area 1.5×1.5 cm. Fields high enough for use with a germanium sample are practical.
Significance of the Mach Principle
Authors: Bridgman P. W.
Published: August 2005

It is shown that the fact that a local Galilean frame of reference or a local instrument such as the gyrocompass preserves its orientation with respect to the universe of stars is adequately explained by the fact that the universe of stars has the unique property of having no detectable mechanical interaction with local bodies. The Mach principle asserts that the universe of stars has some connection with local mechanical phenomena. The considerations of this note suggest that the universe of stars appears to have some connection with local phenomena for the paradoxical reason that it has no connection.
A Reversed Loop-the-Loop
Authors: Sutton Richard M.
Published: August 2005

By relying on the complete similarity of an accelerated coordinate system with a gravitational field, a simple accelerated loop-the-loop is described, by which a ball starting at the bottom rolls backward up over a loop and is caught at the top. Simple means of accelerating the apparatus suffice.
Addition to the Physics Building at the University of Texas
Authors: Watson Robert B.
Published: August 2005

A description is given of the planning and design of a $1.05 million addition to the Physics Building at the University of Texas. The building was intended primarily for instructional purposes. Externally the addition blends well with the existing building, having external finish deliberately chosen to match. Internally, laboratory spaces are made in similar size and shape to existing laboratories for continuity in instructional work and to allow interchangeability, especially at the elementary level. Electrical service is arranged generously. The entire building is air-conditioned for comfort. The internal decor leads to a pleasant appearance, in terms of colors and furniture. Proper sound control further enhances a pleasant atmosphere.
On Maximizing the Information Obtained from Science Examinations, Written and Oral
Authors: Platt John R.
Published: August 2005

A written examination is regarded as a “mapping function” to map student abilities onto a numerical scale. The principles of construction for producing maximum information are examined, with somewhat unconventional conclusions about the best gradation and scoring of problems. Increased length t of an exam probably decreases the errors of discrimination between students no faster than t−12 at best.

An oral examination is regarded as a “search path” to locate the boundaries of a student's knowledge. It is less reliable than a written exam partly because of personal biases and fluctuations and partly because an efficient search plan is so rarely agreed upon and followed by oral committee members. Some common pitfalls are listed and some more efficient search procedures are suggested.
Regarding the Observation of the Lorentz Contraction on a Pulsed Radar System
Authors: Sherwin C. W.
Published: August 2005

Terrell has recently shown that a visual or photographic image of a rapidly moving object subtending a small angle from the point of observation will not show relative distortion in its shape arising from the Lorentz contraction. In contrast to this situation, we show that the image of a moving object as presented on the map, plan-position display of a multiple-beam pulsed radar system will show the Lorentz contraction along the direction of its motion, in addition to the distortions caused by finite transit time of light signals.
Apparatus Drawings Project. Report Number 13. Large Electromagnet
Authors: Marcley Robert G.
Published: August 2005

A simple low cost electromagnet, of relatively large size, that can be constructed in a small shop with minimal machine tools is described. The cross-sectional area of the hot-rolled steel core is 4×4 in. The pole faces can be set to give gap widths ranging from 0 to 14 cm. With a gap width of 0.5 cm and a coil current of 4.5 amp, the field produced exceeds 1 weber/m2. Detailed information on construction methods is given.
Apparatus Drawings Project. Report Number 14. Omegatron for Undergraduate Laboratory Determination of the Ratio e/m of the Proton
Authors: Marcley Robert G.
Published: August 2005

An omegatron, a form of cyclotron, designed for measuring the cyclotron resonance frequency of light positive ions is described. Protons, formed by the collision of electrons and residual gas molecules in the apparatus, are accelerated normal to the axis of two semicylindrical electrodes by an rf electric field. An intense uniform magnetic field, parallel to the electrode axis, causes the protons to follow spiral paths. When the frequency of the electric field is approximately 5 Mc, the magnetic field required is about 4 kgauss, uniform over a volume measuring 2.5 cm diam ×3 cm. From data obtained with this instrument, the student can compute the ratio e/m of the proton. The agreement between this computed value and the accepted modern value for e/m of the proton, is directly dependent upon the accuracy with which frequency and magnetic field strength can be measured.
Cooperative Venture in the Philosophy of Science
Authors: Clancy Edward P.
Published: August 2005

The current trend in the teaching of science, with its increasing emphasis on the broader aspects of physical understanding, demands a deeper appreciation of the structure of science. At present, however, most scientists tend to shun the philosophical implications of their subject, and their students suffer thereby.

It is usually the case that only a large university can command the services of a philosopher of science. This article describes a way in which a college found it possible to provide undergraduate training in the philosophy of science, by using cooperatively the services of a philosopher, a physiologist, and a physicist.
1960 Visiting Foreign Staff Project (V.F.S.P.) Temple University
Authors: Offenbacher Elmer L.
Published: August 2005

The increase in international cooperation for the benefit of science education is noted. The foreign lecturer program in the physical sciences for the 1960 summer institutes for science and mathematics teachers, supported by the National Science Foundation, is described. This program included seven physicists, five chemists, two astronomers, one meteorologist, and one geophysicist. A report of the briefing and evaluation conferences is followed by an introduction to the six physics papers. Three of these are in solid-state physics. There is one each in nuclear physics, radio astronomy, and cosmic rays. Results of a questionnaire to determine the usefulness, among high school teachers, of last year's special March issue are also reported.
On the Education of Physicists in Austria and Israel
Authors: Goldfarb Albert M.
Published: August 2005

The basic systems of education in Austria and Israel are described, each followed by a discussion of the training of a potential physicist or physics teacher in that country.
The Education of Physicists in Sweden
Authors: Friskopp K. G. , Sandström Arne Eld
Published: August 2005

A survey is given of the school system and the background expected of students advancing to university studies in mathematics, physics, and chemistry. The degrees offered by Swedish universities are briefly described. The courses in physics at Uppsala University are described as an example of the education of physicists.
Some Geophysical Aspects of Cosmic Rays
Authors: Sandström Arne Eld
Published: August 2005

After some introductory remarks concerning the primary and secondary cosmic radiation, there follows a section dealing with intensity variations resulting from atmospheric effects. The following two sections deal with the normal effect of the terrestrial magnetic field on the primary cosmic-ray particles. Another section deals with intensity variations (Forbush decreases) correlated to magnetic storms (sudden commencements). The main part of the paper is devoted to the daily intensity variations and an experiment during the IGY on the diurnal variation of the cosmic rays.
Films for Students of Physics
Authors: Weber Robert L.
Published: August 2005

Some 450 films helpful for instruction in physics, mostly at the college level, are listed by field. Addresses of distributors are given. Sources of information about domestic and foreign films are included.
Anniversaries in 1961 of Interest to Physicists
Authors: Barr E. Scott
Published: August 2005

During the year 1961, there will be major anniversaries of the birth or death of 11 men who have figured importantly in the development of physics. Brief accounts of their lives and contributions are presented here.
Relativity of Moving Circuits and Magnets
Authors: Webster David L.
Published: August 2005

Many traditional rules that are contrary to special relativity have persisted in elementary textbooks. The persistence of most of them may be primarily a result of a natural but mistaken neglect of a term in one of the Lorentz transformations. Rules required by relativity to replace these older rules are discussed here with illustrative examples.
Experiments on the Angular Momentum of a Supercurrent and the Possibility of a Supercurrent Gyroscope
Authors: Rose-Innes A. C. , Taylor G. M.
Published: August 2005

It is shown experimentally that the direction of the angular momentum of a circulating supercurrent remains fixed relative to the body in which the current flows. It is not, therefore, possible to make a gyroscope which uses the angular momentum of a circulating supercurrent. The influence of an external magnetic field on the direction of the angular momentum has also been studied.
Apparatus Drawings Project. Report Number 15. Acceleration Carts and Track
Authors: Marcley Robert G.
Published: August 2005

A simple and well-tested design for acceleration carts is described. The size of the apparatus will permit its use in the largest lecture rooms with excellent visibility. The equipment is sturdy and adaptable, but will provide data reproducible to within a fraction of 1%. The materials used and the machining procedures required are conventional. Several accessories are also described.
Experimental Verification of the Gain Formula for Parametric Amplifiers
Authors: Buckley J. K. , Hupert J. J.
Published: August 2005

Recent developments in electronics strongly emphasize the theory and applications of parametric amplifiers. The derivation of the gain formula of a basic type of parametric ampliflier is presented and an experiment described which quantitatively verifies this formula. In order to improve the accuracy of experimentation, the verifying tests are conducted at relatively low radio frequencies despite the fact that parametric amplifiers ordinarily find application at very high or microwave frequencies.
Apparatus Drawings Project. Report Number 16. Apparatus for Measuring the Rutherford Scattering of Alpha Particles by Thin Metal Foils
Authors: Marcley Robert G.
Published: August 2005

An easily constructed apparatus, of simple design, for measuring the Rutherford scattering of alpha particles by thin metal foils is described. An evacuated metal cylinder houses a movable system containing the alpha-particle emitter, a small 0.1 mC Po210 welded-foil source, and, at a fixed distance from this source, an annular ring of scattering material. The face of a type 5819 photomultiplier serves to seal the end of the vacuum chamber, and has at its center the detector, a small circular spot of ZnS(Ag) scintillator. The source, scatterer, and detector are coaxial. The scattering angle may be varied between 28° and 71° by changing the distance from the scattering annulus to the detector, with a resultant change in the counting rate from about 30/min to 4/min. Range and intensity measurements on the source are easily made. If common sense precautions are taken, no radiation hazards will be encountered.
Citations for Distinguished Service
Authors: Olsen Leonard O.
Published: August 2005

The American Association of Physics Teachers has annually cited various of its members for distinguished service to the teaching of physics. Since the practice was started in 1953, twenty-six persons have been cited. The four citations presented on February 4, 1961, are quoted here.
Conservative Fields in dc Networks
Authors: Pugh Emerson M.
Published: August 2005

The desirability of writing o∫E·dl ≢ 0 in dc networks is questioned. Since a general relation of Maxwell is ∇×E = −dB/dt, ∇×E = 0, and o∫E·dl = 0 wherever dB/dt = 0. However, within “sources of emf” charges are transported against this E field. The “forces” responsible for transporting charges against the E field should not be ascribed to an electric field since they depend upon the physical properties of the charged particles.
Unitary Interpretation of Quantum Theory
Authors: Landé Alfred
Published: August 2005

This Anti-Copenhagen interpretation [compare with N. R. Hanson, Am. J. Phys. 27, 1 (1959)] submits that the doctrine of an inherent double nature of matter (and of light) is a most uneconomical hypothesis which would never have been proposed (except for heuristic purposes) had it not been for an oversight of the mechanical particle theory of diffraction by Duane (1923), later incorporated into the quantum mechanics of 1926 in Born's unitary statistical interpretation of wavelike phenomena. Bohr's indeterminacy view comes from a verbal translation of a legitimate wave feature; it is contrasted to the uncertainty of prediction of exact results. The latter is supported by the experiment, the former is not, so that various “epistemological lessons” drawn from Bohr's view stand on brittle ground, which can hardly be reinforced by pointing to the transformation from the first to the second quantization, i.e., from one to another form of a complete and unitary theory. The simple quantum rules of the particle theory (first quantization) can be reduced to general postulates of symmetry and invariance.
Relativistic Oscillator with Natural Forcing Functions
Authors: Ojalvo I. U.
Published: August 2005

The free vibrations of a point on a linear spring with mass determined by the special theory of relativity is extended to the case of forced oscillations. Significant dimensionless parameters of the phenomena are introduced and frequency response curves, which resemble those for a constant mass on a soft spring, are plotted. The method of solution, which makes use of “natural” forcing functions to furnish the excitation, is justified.
Two Models of Brownian Motion
Authors: Mermin N. David
Published: August 2005

Two simple models of Brownian motion are presented. They are used to examine the circumstances under which the detailed velocity dependence of collisions may be adequately represented by a continuous frictional damping. The differences between the equilibrium velocity distributions predicted by a damping approximation and an exact treatment are discussed.
Laws of Physical Laws
Authors: Bunge Mario
Published: August 2005

Statements about scientific laws, called metanomological statements, are examined. The following kinds are distinguished and illustrated: (1) factual metanomological statements like “Newton's laws of motion are invariant under time reversal“; (2) normative metanomological statements such as “The equations of motion are not to depend on any frame of reference”; and (3) methodological metanomological statements like “Law statements should not include egocentric particulars such as ‘now’.” It is claimed that metanomological statements are not laws of nature but a subclass of metastatements, and that they are justified in various ways, since some of them are analytic, others are snythetic, and finally others are in the nature of norms or rules. The status of wide-scope physical principles, such as those of covariance, gauge invariance, and parity, is studied in the light of the above distinctions. In particular, some metascientific problems posed by parity nonconservation and by the combined parity (CTP) theorem are dealt with. Finally, the occurrence of important ought-statements in the language of science is employed against the dichotomy between science and ethics.
Fermi Level Demonstration
Authors: Warner R. M.
Published: August 2005

A simple apparatus demonstrates the dependence of Fermi level upon the temperature and impurity content of a semiconductor. Electrons are represented by ball bearings and states are represented by holes in a plastic sheet. A Fermi probability function template is positioned in energy to accommodate precisely the number of “electrons” originally put into the model, and thus the Fermi level is determined.
Preschool Physics
Authors: Stahl Frieda A.
Published: August 2005

A program of physics demonstrations for the nursery school is being developed in which the children themselves participate as active observers. The basis for each presentation is a phenomenon familiar to the child in his own environment, and the approach is to formulate questions for which answers can be found experimentally. To date, lessons have been devoted to magnetism, light, sound, electricity, and the states of matter. The responses and capabilities of the children are in turn being observed, both during the lesson and in associated play immediately afterward.
Intrinsic Magnetic Moment as a Nonrelativistic Phenomenon
Authors: Galindo A. , Sanchez del Rio C.
Published: August 2005

It is shown that the Hilbert space of spin 12 particles, elementary under the Galilei group, decomposes into two subspaces invariant under the “static” Galilei group. This fact implies a linearization of the Schrödinger equation and suggests a square-root procedure to introduce electromagnetic interactions leading to the right expression for the intrinsic magnetic moment of the particle without using relativity. The procedure can be used to introduce the electron intrinsic magnetic moment in a more convincing way than is usual in textbooks.
Axiomatic Development of the Laws of Vacuum Electrodynamics
Authors: Lehmberg R. H.
Published: August 2005

The laws of classical vacuum electrodynamics are derived from three postulates relating to interactions among charges. Two of these describe the behavior of a moving test charge in an electrostatic field. Application of relativistic arguments to these two yields the Lorentz force law and Maxwell's equations for unaccelerated charges. The third postulate states that these laws are unaltered if the source charges are accelerated. The experimental basis of this postulate is discussed, and is found to be generally inconclusive.
Dynamics of Ionized Gases
Authors: Steginsky Bernard
Published: August 2005

The dynamics of a classical, ionized gas is presented in a way which stresses the role of individual particles in contributing to the gross behavior of the gas. An important distinction is drawn between a weakly ionized and a strongly ionized gas, and it is shown how the latter, through long-range interaction forces, exhibits the phenomenon of collective behavior. Three methods of description employed in the study of ionized gases are reviewed. These are the microscopic theory, the velocity-distribution method, and the macroscopic theory. Part of the section on the macroscopic theory is devoted to a consideration of the special case of a perfectly conducting gas in order to illustrate typically the pitfalls which may be encountered in a narrow application of the continuum approach to magnetohydrodynamics.
Presentation of Newtonian Mechanics
Authors: Austern N.
Published: August 2005

Classical mechanics is sketched in elementary terms, from a sophisticated point of view. It is stressed that no formulation of the laws of motion constitutes a complete theory, susceptible of being compared with experiment. Instead, what these laws do is to show how to formulate theories of particular motions, by the introduction of (additional) laws of force. Because the basic force laws are simple in a suitable coordinate system, the over-all theory is simple, and useful, and is believed. The presentation given is designed for pedagogic use.
Convenient Equations for Projectile Motion
Authors: Winans J. Gibson
Published: August 2005

Quaternion multiplication of the basic vector equations for uniformly accelerated motion gives two equations, v2 = u2+2a·s and a×s = v×u, which provide a simple solution for some projectile problems. For a given s and a, the two times of flight are described by t1t2 = 2s/a.
Initial Value Solution of Maxwell's Equations in Cold Plasma
Authors: Gerwin Richard A.
Published: August 2005

Kirchoff and Liouville have derived the general initial value solution to Maxwell's equations in vacuum, i.e., the wave equation. Such a calculation is presented here for the case of a cold, collisionless, uniform, electron plasma.
Apparatus Drawings Project. Report Number 30A. A Versatile RC-Filtered Low-Voltage Power Supply and a Calibrated Direct-Coupled Amplifier
Authors: Marcley Robert G.
Published: August 2005

A versatile RC-filtered power supply and a calibrated direct-coupled amplifier are described. The power supply furnishes operating power to various electronic devices developed for two large introductory laboratories. It provides about 250 V dc at its rated output of 70 mA, and 2.5 A at 6.3 V ac. The direct-coupled amplifier has 6 output ranges, from 0.5 to 150 V full scale. Its normal input resistance is 22 MΩ, with stable operation at input resistances of 125 MΩ being practical. Output is displayed on an external 100-μA meter. The method of achieving calibration accuracies of ±2% or better, using ±10% tolerance carbon resistors is described. Both instruments are stable and extremely reliable, requiring only standard commercial components and conventional tools and techniques for construction. The cost for parts is $16.26 and $22.05, respectively. The article contains full information regarding construction.
Some Aspects of Physics Research in non-Ph.D. Granting Institutions
Authors: Kruschwitz Walter H.
Published: August 2005

More than 265 physics departments that offer an undergraduate physics major but do not have a Ph.D.-level graduate program submitted answers, at the request of the Commission on College Physics, to a general questionnaire dealing with departmental programs and practices. The section of the survey concerned with research in these departments is summarized in this report.
Derivation of Maxwell's Equations and the Boundary Conditions from Coulomb's Law
Authors: Green T. A.
Published: August 2005

It is shown that the traditional methods used to derive Maxwell's equations and the boundary conditions from Coulomb's law are mathematically unsound. One widely used line of argument fails as a proof because it depends on the unwarranted extension of Maxwell's equations in integral form from the case of N point charges to that of continuous volume and surface distributions of charge. The other most frequently presented argument fails because it rests on unwarranted differentiations of improper integrals and the application of Gauss' and Stokes' theorems to situations in which the standard proofs of these theorems do not hold. An alternative elementary approach is presented.
Independence of the First and Second Laws of Thermodynamics
Authors: Schamp Homer W.
Published: August 2005

It is pointed out that several conclusions ordinarily treated as being based on both the first and second laws of thermodynamics are actually dependent only on the second law. These include the efficiency of engines working between two heat reservoirs, an absolute thermometric scale, and the Clapeyron equation.
Remark Concerning the Eigenvalues of Orbital Angular Momentum
Authors: Buchdahl H. A.
Published: August 2005

That the eigenvalues of the components of orbital angular momentum are integral is most often inferred from the requirement that the Schrödinger representatives of the angular momentum eigenkets shall be single-valued functions of the spatial coordinates. Physical interpretation, however, requires only that the squared modulus of any wavefunction shall be single-valued, which leads only to the weaker conclusion that the eigenvalues are either all integral or all half-odd integral. It is shown here in an elementary manner that the eigenvalues are in fact integral, any explicit appeal to single-valuedness being avoided.
Compressible Fluid Flow and the Theory of Characteristics
Authors: Anderson Gordon D. , Band William
Published: August 2005

This paper calls attention to the contemporary need for an elementary discussion of the nonlinear features of the equations of hydrodynamics and their application to supersonic and high pressure phenomena. A simplified account of the method of characteristics is presented, with illustrations from the theory of the ideal fluid, the thermally conducting fluid, and the viscous fluid. An “asymptotic paradox” is briefly discussed.
Apparatus Drawings Project. Report Number 32. Launching Tube for a Laboratory Experiment on Projectile Motion
Authors: Williams T. Walley
Published: August 2005

A ball rolled down the tube of this apparatus is launched upward at various elevation angles as a projectile. Using as data the heights of three points on the tube, the student must consider potential energy, linear and rotational kinetic energy, frictional corrections, and projectile motion to predict the impact point of the ball.
A Device to Demonstrate the Reciprocal Lattice Concept in Relation to Single-Crystal X-Ray Diffraction Patterns
Authors: Mathieson A. McL.
Published: August 2005

The condition for diffraction of x rays is the coincidence of a reciprocal lattice point with the circumference of the reflecting circle. A mechanical-optical analogy is used to illustrate the genesis of single-crystal diffraction patterns.
Lecture Demonstration of Electron Diffraction
Authors: Fowler John M. , Warren William , Lambe Edward D.
Published: August 2005

A demonstration of the diffraction of a beam of electrons by a thin film of gold is constructed inside a black-and-white television tube. A pattern of concentric diffraction rings around a central maximum appears on the screen of a tube in which a thin gold film has been inserted in front of the electron beam. Since the two brightest of these can be seen clearly from a distance of at least forty feet in a darkened lecture room, the demonstration is suitable for large audiences.
Long-Time Transition Probabilities for a Two-Level System Interacting with a Stochastic Electromagnetic Field
Authors: Cummings F. W.
Published: August 2005

The purpose of this paper is to demonstrate solutions of Schrödinger's equations for a two-level quantum system which is coupled to a radiation field. The electric (or magnetic) field, which is considered as a definite (if unknown) function of time E(t), is characterized by a power spectrum or its related correlation function. Long-time transition probabilities are obtained in the form of a contour integral under the assumption of small atom-field coupling. The contour integral can be easily evaluated for many cases of interest. In particular, it is shown how a two level system in interaction with a blackbody approaches the Maxwell-Boltzmann distribution as t → infin.
An Inexpensive Nuclear Laboratory
Authors: Zucker Charles
Published: August 2005

A description of the basic equipment necessary for instituting a nuclear laboratory is presented. A series of fundamental neutron experiments utilizing a neutron source and a neutronhowitzer are outlined.
Determination of a Potential from its Energy Levels and Undetectability of Quantization at High Energy
Authors: Keller Joseph B.
Published: August 2005

The problem of determining a spherically symmetric potential from its energy eigenvalues En in states of zero angular momentum is solved approximately. The corresponding problem for a one-dimensional potential is also solved. It is incidentally shown that the large eigenvalues depend only upon the width of the potential as a function of height rather than on its precise shape. The level spacing En+1−En is investigated for a one-dimensional potential. It is shown that the spacing does not increase faster than En for large values of En. Thus the relative spacing (En+1−En)/En decreases faster than 1/En for large En. This fact is proposed as an explanation for the undetectability of quantization at high energies. It is also shown that of all potentials having a given width at the energy E and a given depth, the square well has the greatest spacing at E. The corresponding classical mechanical problems, which concern nonlinear vibrations, are also considered.
Aether Concept Versus Special Relativity
Authors: Ahrens Tino
Published: August 2005

The concept of “the one-way experiment” is discussed and shown to be meaningless. It is furthermore shown that the pure information extracted from two-way experiments forces one to relinquish the notion of an aether-rest-frame as an operationally significant privileged reference frame. Great care is exercised in defining (spatial) coincidence and (temporal) simultaneity.
Simplified Bridge and Resonant Circuits for the Measurement of Resistance in Absolute Units
Authors: Ainslie D. S.
Published: August 2005

This paper outlines modifications in the bridge and resonant circuit method of measuring resistance in absolute units, as outlined by the author in a previous paper. These modifications simplify the experimental procedures without any loss of accuracy.
The Magnetic Pole in the Formulation of Electricity and Magnetism
Authors: Katz Robert
Published: August 2005

The use of the magnetic pole in the development of the concepts of electricity and magnetism leads unambiguously to a relativistic formulation of the field vectors which is well within the grasp of the sophomore student. The development is wholly consistent with Maxwell's equations and leads to clear and understandable definitions of the field vectors both in vacuum and in the material medium, as well as to the relations defining the transformations of the field vectors.
Fresnel Diffraction with Phase Objects
Authors: Sussman Milton H.
Published: August 2005

An analytic expression is derived for the intensity distribution in the Fresnel diffraction“image” of a transparent object with arbitrary phase shift. Comparisons are made with the Cornu spiral treatment of slits and fine wires. The effects of wavelength variation and finite source width are indicated and appear in a brief mathematical appendix; methods of evaluating Fresnel integrals for plotting purposes are briefly described.
Solution of a Combinatorial Problem—Intermediate Statistics
Authors: Fisher Michael E.
Published: August 2005

This article draws the attention of physicists to the simple yet powerful mathematical technique of “generating functions” and illustrates the method by solving the problem: “How many ways are there of distributing m identical marbles between n numbered boxes when no box may hold more than M marbles?” This problem, which includes both Bose-Einstein and Fermi-Dirac statistics, has been considered recently in this Journal by McLachlan and Chamberlain using geometrical analogies.
Apparatus Drawings Project. Report Number 22. Proportional Counter
Authors: Marcley Robert G.
Published: August 2005

A cylindrical cathode-coaxial anode proportional counter, designed for an undergraduate laboratory, is described. A collimated beam of α particles can be directed into the counter at any point along a narrow longitudinal window in the cathode wall and used to examine the electric field surrounding the anode structure at any point along its length. The anode wire has an enlarged section at one end and is surrounded at the other by an independently biased coaxial auxiliary electrode. The effectiveness of these two geometrical methods for controlling the production of secondary ionization can be studied, as can the effects of varying gas composition, pressure, and operating voltage. A variable output-2000-v power supply, pulse amplifying and counting equipment, a cathode ray oscilloscope, and a small mechanical vacuum pump are also needed for these experiments. Detailed information on construction of the counter and gas handling system is given.
Measurement of the Beta Spectrum of I128 in an Undergraduate Laboratory
Authors: Prentice J. D. , McNeill K. G.
Published: August 2005

An account is given of an experiment performed by final year students in a three-hour laboratory period which enables them to obtain a Kurie plot and a reasonable end point for the ground state beta transition of I128. Use is made of a 1-in. NaI crystal, a photomultiplier, and a single-channel analyzer.
Gratings Prepared by Photographing Double- and Multiple-Slit Fraunhofer Diffraction Fringes
Authors: Rao K. V. Krishna
Published: August 2005

A simple method of preparing gratings that give any desired number of orders of spectra is described. The method consists in photographing double- and multiple-slit Fraunhofer diffraction patterns, taking some special precautions.
Energy Balance in Extensive Air Showers
Authors: Green John R.
Published: August 2005

The production of an extensive air shower is discussed starting with the elementary nuclear interaction and proceeding to the development of the various components of the shower. Mention is made of experimental methods used to obtain information about the different components, particularly with regard to the energy. Emphasis is placed on the division of the energy of the primary particle among the various components and the way in which this is accomplished. Some numerical values are given to typify the magnitudes involved.
A Radioactivity Experiment Using Activities Filtered from the Air
Authors: Whyte G. N. , Taylor H. W.
Published: August 2005

An experiment involving radioactive decay and the successive transformations among members of a radioactive series is described. The source is dust filtered from the atmosphere and bearing the radioactive decay products of radon and thoron. Equations describing the expected variation of counting rate with time are presented, the experimental procedure is outlined, and illustrative results are shown. The procedure for estimating the concentration of radon in the air is also indicated. The experiment is suitable for advanced undergraduate physics students and for students of reactor and health physics.
Electric Production of Ripples
Authors: Palmer Frederic
Published: August 2005

The rise of distilled water about a highly charged wire touching the surface is described. This phenomenon provides a simple means of producing various systems of ripples. The mechanism of the rise and fall of the water is discussed. The rise is found to take place only when the wire is charged positively. If the rise is great enough, the water in the jet falls so rapidly it spreads out over the surface forming a “cake” which eventually merges with the rest of the water. As this happens, a secondary system of ripples may be formed with a velocity greater than the primary system.
Restless Harmonic Oscillator
Authors: Hane Michael
Published: August 2005

An ordinary harmonic oscillator in the laboratory is never completely at rest relative to the earth. Small fluctuations in its position are caused by thermal, quantum-mechanical, and gravitational effects. We discuss in this paper the origins and magnitudes of these fluctuations. The range which the fluctuations may have for extreme physical conditions (e.g., high and low temperatures) is compared with normal terrestrial values.
Report of the Denver Conference on Curricula for Undergraduate Majors in Physics
Authors: Bottom Virgil E. , Hilton Wallace A. , Lodge John I. , Long Vernon L. , Schillinger Edwin J. , Way Harold E.
Published: August 2005

A conference held in Denver, Colorado, during August, 1961, was concerned with the need for bringing about an immediate improvement in the quality of education offered by four-year colleges to their physics majors. The roles that the introductory course, the intermediate courses, the laboratory, undergraduate research, and independent work should play in undergraduate physics majors were discussed at considerable length. Among the chief recommendations made at the conference were: the introductory physics course, using the concepts of the calculus, should begin in the freshman year, preferably in the first semester; all courses, particularly the intermediate ones, must place increasing emphasis on the analytic nature of physics, and the courses must be organized into a sequential arrangement that utilizes the growing maturity of the student in both physics and mathematics; the thoroughness and depth of the laboratory work should increase with the developing skill and insight of the student and should culminate with work at or near the research level; research and independent work are important to the intellectual development of the student and should be strongly encouraged.
Introductory Courses in Physics Major Curricula
Authors: Zemansky Mark W.
Published: August 2005

Introductory courses for students who expect to become physics majors must furnish the background for the intermediate courses at the same time that they serve as a test of the student's ability and interest. If these things are to be accomplished better than in the past, changes should be in the direction of doing in better ways what is already being done, rather than in the direction of some of the radical departures from current practice that have been suggested. Some of the suggestions that have been made are discussed, and it is concluded that they will not result in better preparation.
The Role of Experimental Work
Authors: Michels Walter C.
Published: August 2005

An important function of the laboratory in undergraduate physics instruction is considered to be the illustration of the way in which the interaction of theory and experiment results in the growth of physical science. When existing practices are measured by their degree of success in fulfilling the function, many are found to be deficient. On the other hand, experiments under way in various departments of physics suggest ways in which the laboratory can be made a unique tool for instruction. A set of general requirements for good experiments is proposed and the problems of their application are discussed.
Intermediate Physics Courses for the Undergraduate Physics Major
Authors: Correll Malcolm
Published: August 2005

Present demands, which result from the growth of physics in content and depth, will be satisfied only if we use our teaching time more effectively. The movement of material previously taught in graduate school into the undergraduate curriculum can be allowed for if we take full advantage of improved preparation in the high schools, particularly in mathematics. It is suggested that intermediate courses might be organized about problems that are connected by common principles and methods, rather than about the particular “quasi-sensory” groups of phenomena that have determined the subject matter in the past, and that stronger emphasis be placed on physical content, rather than mathematical manipulation.
Independent Study and Research in the Undergraduate Physics Curriculum
Authors: Schilling Harold K.
Published: August 2005

The nature of physics is such that no one can separate its subject matter from the research activity that has generated our knowledge. Hence research experience and independent study are essential parts of the education of any physicist. Arguments are advanced for including activities of this sort in the undergraduate program, and ways in which this can be done are discussed.
The Stop-Light Dilemma
Authors: Seifert Howard S.
Published: August 2005

Far down the road the light is green, and you hurry toward it at or above the legal speed limit, hoping to reach the intersection before the light changes. While you are yet a short distance d0 feet away, traveling with a high velocity v0, the light turns yellow. You are now faced with an instantaneous decision: shall you tramp hard on the brakes and decelerate at your maximum rate of a− ft/sec2, or press the gas pedal to the floor and accelerate at your maximum rate a+ ft/sec2? You may not stop in time; if you elect to make a run for it, that faltering engine may not get you through before the yellow light turns to red. If the yellow-light duration is T seconds, and the intersection is s feet wide, then you may successfully choose either alternative if (v0T+12a+T2−s)>d0>12(v02/aminus), but if the left or the right inequality is reversed, you will not be able to run through or to stop, respectively. If both are reversed, a violation of the law is probable. The discussion presents the range of values of safe and unsafe combinations of the six basic parameters v0, d0, s, T, a−, and a+.
Single Valuedness of Wave Functions
Authors: Merzbacher E.
Published: August 2005

The requirement that the quantal wave function be single-valued is examined in the light of two recent developments: The effect of a magnetic vector potential on a particle moving in a multiply connected field-free region (Aharonov-Bohm effect), and the flux quantization inside a superconducting ring. Both of these effects are new applications of conventional elementary quantum mechanics. The single-valuedness problem is considered, with its historical background, for particles with no spin, particles with spin 12, and rigid bodies. It is shown that the single-valuedness condition, if properly adapted to the particular physical model, is deeply rooted in the foundations of quantum mechanics. However, wave functions which superficially appear to be double-valued are useful in an helicity representation of spinors and in the construction of nuclear wave functions.
Development of the Kinetic Theory of Gases. VI. Viscosity
Authors: Brush Stephen G.
Published: August 2005

This article reviews the development of theories of transport phenomena by Maxwell, Boltzmann, Chapman, and Enskog, and their application to the calculation of the viscosity coefficient. Maxwell's original mean-free-path theory for hard spheres (1860) was refined by Tait, Sutherland, Rayleigh, and Jeans, but suffered from inherent limitations because the velocity-distribution function in a nonuniform gas was unknown.

Maxwell (1866) and Boltzmann (1872) proposed more general methods for dealing with transport processes in gases; these methods form the basis of the modern theory. However, Maxwell and Boltzmann did not manage to solve their equations except in a few special cases. It was not until half a century later that Chapman (1916) and Enskog (1917) independently succeeded in determining the velocity-distribution function to an accuracy sufficient for the calculation of transport coefficients for any assumed force law. The extension of the theory to dense gases of hard spheres was accomplished by Enskog (1922), who obtained an expression for the viscosity coefficient similar to one proposed by Jäger (1900).
Thermal Imagery: New Medium for Demonstrating Phenomena in Heat and Thermal Radiation
Authors: Strickler Allen
Published: August 2005

The thermosensitive double iodide of mercury and silver (HgI2·2AgI), which changes reversibly from yellow to red on heating, is made the basis of a thermal imaging medium permitting new, vivid demonstrations of many heat phenomena. The sensitive pigment is coated on a thin insulating sheet such as cardboard. The back of the sheet may be variously coated with black, metallic, and electrically conductive areas to absorb, reflect, or inject heat in recognizable patterns. Images are produced by friction, conductive heat transfer, convective heat flow, infrared absorption and reradiation, focusing and shadow casting with infrared rays, electrical heating and evaporative cooling.