bluuebunny/crossref_metadata_2025 huggingface dataset:
Whip Effect in a Falling Chain
Authors: Heywood W. A. , Hurwitz H. , Ryan D. Z.
Published: August 2005

A simple experiment is described for demonstrating the whip effect in a falling chain. The observed reduction in fall time due to the concentration of energy in the falling section of the chain agrees well with the assumption of small energy loss in the loop of the chain. The measured tension at the support point rises far above the maximum value which would be reached in the absence of energy concentration.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 70. Mechanical Clocks in Fifteenth-Century Art
Authors: Watson E. C.
Published: August 2005

Small table or wall clocks with weight-driving mechanism and escapement came into use during the fifteenth century. They are clearly delineated in some of the so-called “planet-pictures” engraved during the early part of the second half of the century. Three such plates are here reproduced and discussed.
The Siphon Balance
Authors: Dodd Laurence E.
Published: August 2005

A balance of special design demonstrates the principle of the siphon, and incidentally, if desired, that of Archimedes at the same time. A vertical rod, ending at the top in a hook that hangs from a knife-edge, supports a horizontal platform at its center. Placed symmetrically on the platform near its ends, are two equal beakers containing water in equal amounts. If the beakers are connected by a siphon tube, when water is added to or taken from either of them, the system will rebalance itself automatically. After rebalance, the volumes of water in the beakers are again equal. Putting a floating object into either beaker causes the same deflection that the same weight of water would (Archimedes' principle), and again the pointer returns automatically to zero. If the floating object is now removed, the balance behaves as if the same weight of water had been removed. But laying a weight on the platform outside a beaker causes the siphon to increase the deflection to a new equilibrium value.
Physics in Engineering—A Rejoinder
Authors: Varney Robert N.
Published: August 2005

The contentions are raised that a thoroughly integrated presentation of fundamentals is highly essential to engineering students and must be given regardless of the title or department of the professor doing it, that physics departments and texts are doing it today, not perfectly perhaps, but under considerable difficulties, and finally that physicists still have an approach and a point of view that is decidedly more basic than that of the engineer and is decidedly healthy for the engineering student to learn. A suggestion is offered for expanding the crowded four-year curriculum by bringing students from high schools a year earlier.
Nature of the Primitive System in Kron's Theory
Authors: Hoffmann Banesh
Published: August 2005

The idea of a primitive system in Kron's theory is shown to involve two distinct concepts and to be not well defined. An attempt is made to give a sharper definition. The discussion is confined to electrical networks. The anomaly is stressed that though Kron's primitive network and the given network are physically different, the transformation laws imply that their instantaneous power inputs are equal. Ways proposed by various authors of avoiding this anomaly are briefly discussed. Some ignore the primitive network; others make the primitive network physically equivalent to the given network, either by changing the primitive network or by changing the given network. Since this does not accord with the method by which Kron forms his primitive network, the view is put forward that the primitive network is physically different from the given network. A new network, the “connected primitive network,” is introduced which, among other things, clarifies the physical significance of a singular C-transformation. The given network and primitive network are considered to stand for infinite families of networks; the singular C-transformation then selects from the family of primitive networks a subfamily that coincides with the family of given networks.
The Néel Theory of Ferrimagnetism
Authors: Smart J. Samuel
Published: August 2005

The Néel theory of ferrimagnetism is a molecular-field theory of magnetic ordering in systems which contain nonequivalent substructures of magnetic ions. The two principal results of the theory are (a) the curve of reciprocal susceptibility vs temperature above the Curie temperature is an hyperbola, and (b) the curve of spontaneous magnetization vs temperature below the Curie temperature may have any one of a number of unusual forms. The exact form depends on the distribution of magnetic ions between the substructures and on the relative values of the molecular field coefficients.

The agreement between the predictions of the Néel theory and some experimental observations on ferrites is discussed briefly.
On the Development of the Compound Nucleus Model
Authors: Wigner Eugene P.
Published: August 2005

The cross sections of certain nuclear reactions, as functions of energy, show sharp maxima and low values between the maxima, thus exhibiting a great similarity to line spectra. The compound nucleus theory was originally designed to explain this structure and to describe the corresponding nuclear reactions. After a brief description of the picture which the compound nucleus theory presents for these reactions, the story of the extension of the theory to describe a wide variety of reactions is presented. This includes an outline of the mathematical concepts which the extended theory uses. The last part of the article deals with the connection between the so-called principle of causality, which expresses the fact that the scattered particle wave cannot leave the nucleus before the incident particle wave has reached it, and the formulas of the generalized compound nucleus theory.
Torque Condition for Equilibrium
Authors: Scott William T.
Published: August 2005

The torque condition for equilibrium can be derived from Newton's first and third laws, the postulate of central forces, and some geometrical considerations. Such a derivation, or adequate statements about its possibility, were not found in 52 elementary textbooks examined. A simple form of this derivation is given.
Elementary Course in Solid State Physics
Authors: Bessey William H.
Published: August 2005

Engineering educators are becoming very interested in solid state physics. A course is described which is designed for seniors and beginning graduate students in both physics and engineering. Some of the difficulties in the choice of textbook and subject matter are pointed out, difficulties due in large part to the lack of background of the students. A selected bibliography, with comments, is given in the appendix.
Simply Constructed Ampere Balance with Good Precision
Authors: Edwards R. L.
Published: August 2005

Although the ampere balance is today the primary standardizing device for the measurement of electric current, such balances are not available in the laboratory supply houses. Elaborately designed ampere balances have been made in physics departments with large resources, but the models we have seen elsewhere are satisfactory for demonstration purposes only. This paper describes the construction of a simple balance well suited for quantitative laboratory work as well as classroom demonstration.
Critique of Teaching Objectives in Secondary Schools
Authors: Wise Harold E.
Published: August 2005

Formal statements of the objectives of secondary education place major emphasis on the “common needs of youth” and minimize the importance of developing the potential abilities of outstanding students and their preparation for college. Emphasis in the preparation of teachers is on the professional aspects of teaching often at the expense of subject matter, while the school program suffers from a number of “maladies” such as “curriculum dilution,” the philosophy of “no failures,” and an excess of extra-curricular activities.

To increase the supply of potential physicists, it is suggested that emphasis be placed on the better preparation of teachers and on securing their continuing tenure on a 12-months basis at salaries comparable to those paid in professions requiring similar ability and preparation. To accomplish these ends, it is suggested that high school science and mathematics teaching be placed under Federal regulations somewhat similar to those which now govern Vocational Agriculture and Home Economics under the Smith-Hughes Law.
Effectiveness of the Case-General Electric Science Fellowship Program for High School Physics Teachers
Authors: Olsen Leonard O. , Waite Rollin W.
Published: August 2005

The effectiveness of the Case-General Electric fellowship program for teachers of secondary school physics has been studied. The impact of the program on the training of scientific and engineering personnel through advanced training of physics teachers is discussed. An indication of the general problems faced by teachers in their respective schools is set down, along with specific examples of improved teaching.

The effect of the program is set forth convincingly through the results of a questionnaire sent to former Fellows.

The records of Fellow's students who attended Case have been examined. Their performance at Case is quite appreciably above the average, showing that more and better students are being trained for scientific and engineering careers as a result of the GE Science program.
Teaching Aids: Equipment and Facilities
Authors: Eaton V. E.
Published: August 2005

The formation and work of the AAPT Committee on Scientific Apparatus for Educational Institutions is described. Many suggestions are made for increasing the variety and appeal of apparatus used in teaching physics, with the ultimate objective of increasing student interest in the subject, and of meeting the growing demand for research physicists and physics teachers.
Influence of Permeable Membranes on the Measured Values of Osmotic Pressures
Authors: Barr T. A.
Published: August 2005

An “operational” definition of osmotic pressure is presented and the difference between this definition and the thermodynamic definition of osmotic pressure is pointed out. By the use of a negative pressure osmometer a formula is developed to express the values of “osmotic pressures” when the osmometer membrane is permeable to both solvent and solute. A membrane factor B is introduced to account for the efflux of solute from the osmometer. B is evaluated in terms of the effective solute diffusion coefficient, D.
A One-Semester Physics Course for Liberal Arts Students
Authors: Peck R. A. , Haisley W. E.
Published: August 2005

The course described represents an attempt to lead freshmen not specializing in physics to an understanding of the nature of scientific endeavor which may provide an adequate scientific foundation for twentieth-century citizenship.

Holton's admirable general education text was employed to organize the study and define its semihumanistic approach. Equal attention was directed to a tightly integrated core of technical physics and to the interplay between science and the social environment. Technical material was organized about Newton's synthesis in mechanics and Bohr's in atomic structure. For the role of physics in human affairs subject matter was drawn from outside reading in selected historical and philosophical expositions and brought into the course through written papers and symposia. The customary laboratory curriculum was modified to provide a gradual increase in pace and difficulty throughout the semester.

Departures from conventional techniques are described in detail and their merits and shortcomings evaluated. Most of the innovations appear to have been successful in some degree.
Logical and Philosophical Foundations of the Special Theory of Relativity
Authors: Grünbaum Adolf
Published: August 2005

It is argued that the correct understanding and teaching of the special theory of relativity are still impaired by a number of specific, widespread misconceptions. To remove these, the relevant definitional, experimental, and philosophical foundations of the kinematics of the theory are made explicit by reference to the following issues: (i) the relativity of simultaneity, which arises, in the first instance, within a single Galilean frame, (ii) the principle of the constancy of the speed of light, which rests on three distinct experimental facts as well as on an important convention, made possible by a fourth experimental result, (iii) the compatibility of the invariance of the speed of light with the absence of a retardation on the part of moving clocks, and the role of that optical principle in the deduction of the Lorentz transformations, (iv) the merits of the ad hoc charge against the Lorentz-Fitzgerald contraction hypothesis; the philosophical sources of the difference between Lorentz' and Einstein's interpretations of the transformation equations.
Note on the Study of Simple Harmonic Motion
Authors: Chen Henry S. C.
Published: August 2005

A new approach to the study of simple harmonic motion is presented. A record is taken of the positions at different times by means of a spark timer. From the limits approached by the average velocities, instantaneous velocities are obtained. From the limits approached by the average accelerations, instantaneous accelerations are obtained. A linear relation shows the direct proportionality between acceleration and displacement. The period of SHM may be determined from the slope of this straight line and compared with the experimental value.
New Geometric Representation of the Lorentz Transformation
Authors: Amar Henri
Published: August 2005

Most geometric representations of the Lorentz transformation use either imaginary angles or imaginary space-time coordinates. A new and simple representation is proposed using only real coordinates and real angles, and allowing a graphical illustration of the major features of the Lorentz transformation.
Production of Chladni Figures on Vibrating Plates Using Continuous Excitation
Authors: Jensen Harald C.
Published: August 2005

A method of producing Chladni figures by continuous excitation is described. Thin metallic plates are placed in the sound field of a 15-watt (or higher) loud-speaker driven by an audio-oscillator and power-amplifier combination. Advantages of this method, especially for demonstration purposes, are enumerated.
Kundt Tube Dust Striations
Authors: Carman Robert A.
Published: August 2005

An interesting anomaly in the familiar Kundt tube experiment and the eighty-year search for an interpretation is reviewed for teachers of physics. Unfortunately the correct explanation of this phenomenon, although available, is rarely cited and known to very few. The work and explanation of Andrade are presented and expanded in hopes of remedying this situation.
Bent Mica Focusing X-Ray Spectrograph for a Course in Atomic Physics
Authors: Weymouth John W. , Bauer Norman
Published: August 2005

This paper describes a simple bent mica x-ray spectrograph that was built for use in a senior course in atomic physics. The theory and construction of the spectrograph are discussed and its application to the study of the properties of x-rays by means of the recording of direct and fluorescent radiations is described.
Lecture Demonstration of Relativistic Behavior of Electrons
Authors: Peter Martin
Published: August 2005

A lecture demonstration is described, which allows verification of the relativistic relation between kinetic energy and momentum, (mc2+E)2 = m2c4+c2p2. Electrons are accelerated by a small high-voltage generator (van de Graaff, of approximately 250 kv) and deflected in a magnetic field of approximately 100 gauss. The measured values of high-voltage and deflecting magnetic field are plotted on a straight line which represents the relation given above.
Spinor Theory and Relativity. I
Authors: Payne W. T.
Published: August 2005

The elementary properties of relativistic spinors of first rank are developed geometrically, on the basis of the idea that the space in which they reside is either the positive or the negative branch of the light cone. As an aid in the development, the Lorentz transformations of points on the light cone are first studied in considerable detail.
On Deriving the Formulas for Electromagnetic and Other Forces from the Interaction Energy of the Fields
Authors: Armstrong H. L.
Published: August 2005

A treatment of some force and energy relations of electromagnetic theory is given, in which the energy density of the field is postulated as fundamental, and the force relations are derived by transformations of vector integrals. This focuses attention on the fields as the concepts of especial interest; the attention to interaction energies of fields offers interesting analogies to the methods used in wave mechanics.
Spin Resonance Line Shape
Authors: Kaplan Jerome I.
Published: August 2005

A method is given for the calculation of the spin resonance equations based on solving for the spin vector expectation value subject to several external conditions. The value of the method is limited to the case where the system can be described by one relaxation time.
Note on the Derivation of the Equation v = (T/μ)
Authors: Chen Henry S. C.
Published: August 2005

A simple, straightforward derivation is given for the speed of a transverse wave along a stretched string. It is free from the many limitations and assumptions which are generally found in other derivations. The only assumption which has to be made here is that the wave travels with a constant speed and small amplitude.
Hydromagnetism. I. A Review
Authors: Elsasser Walter M.
Published: August 2005

This paper gives a survey of the theories (Part I) and phenomena (Part II) of cosmic magnetism, extending from geomagnetism over solar and sunspot magnetism to stellar and interstellar magnetic fields. The theoretical treatment is purely classical and Maxwelliam. Most cosmic fluids, being highly ionized, are excellent conductors; this implies that the displacement current can always be neglected. The fundamental equations of hydromagnetism are the electromagnetic field equations together with the hydrodynamic equation, both containing coupling terms between magnetic field and motion. Among other theoretical developments, the “dynamo” theory which ascribes the cosmic magnetic fields to amplifying processes in the moving fluid is described and it is shown that it is well suited to represent the observed phenomena of the generation and maintenance of cosmic magnetic fields.
Heat Units and Temperature Scales for Calorimetry
Authors: Stimson H. F.
Published: August 2005

Calorimetry is the measurement of quantities of heat. Temperature scales are usually involved. The General Conference on Weights and Measures adopted the International Temperature Scale (practical scale) in 1927 and its first revision in 1948. This scale is nearly parallel to the thermodynamic scale, proposed by Kelvin in 1854. In 1954 the General Conference redefined the Kelvin Scale, in the manner which Kelvin originally said “must be adopted ultimately,” by assigning a value for the temperature of a single fixed point, viz. 273.16° for the triple point of water (ice point=273.15°). Several calories have been used in the past but the joule was adopted for the unit of quantity of heat in 1948. The need is stressed for using units of heat which are unambiguous.
Circuit for Measuring High Resistance or Low Capacitance
Authors: Kersten Harold J. , Klingenberg E. W.
Published: August 2005

A convenient circuit for making linear measurements of high resistances and low capacitances consists of a conventional power supply, a relaxation oscillator, and a flip-flop circuit for alternately connecting and disconnecting a seconds timer. The relaxation oscillator makes use of the WL 759 cold-cathode, glow-discharge tube.
Feasibility of a Nonrelativistic Explanation for the Advance of the Perihelion of Mercury
Authors: Gerjuoy E.
Published: August 2005

Nonrelativistic explanations for the advance of Mercury's perihelion are described, and the point made that Einstein's theory is favored over these because of his theory's intellectual appeal. Consideration is given to the possibility that the perihelion advance could be explained by hypothesizing a charge on the Sun which induces a dipole on Mercury and thereby causes a departure, from inverse square, of the total force between the Sun and Mercury. It is shown that such a hypothesis runs into serious difficulties. The results of the calculations are thought to be illustrative of the difficulties which are encountered by an attempt to account for the advance by postulating heretofore unsuspected interactions between Mercury and other bodies.
Electrostatic Dynamometer
Authors: Little Noel C.
Published: August 2005

Three forms of an instrument which combines the functions of the absolute electrometer and the current balance are described. The theory of this instrument and its application in determining current, potential, and resistance in the intermediate course in electricity and magnetism are discussed briefly.
Introductory Physics in a Program of Directed Studies
Authors: Major J. K.
Published: August 2005

Orthodox courses and textbooks in elementary physics are criticized for too much material, too little interrelation to other disciplines, too much emphasis on practical applications, too little modern physics, and too little opportunity for student initiative. The selective rather than general approach is briefly reviewed, and a course described which is part of the Directed Studies in the Liberal Arts at Yale, an experiment in a prescribed curriculum for the first two years. Elementary Atomic Physics, with no prerequisites, devotes the first term to a background in classical physics centered around particle dynamics and electrodynamics, and the second term to atomic and nuclear physics. General reaction appears favorable, and screening students according to backgrounds, introducing seminars with opportunities for laboratory experiments, and integrating physics more closely with other courses are suggested improvements.
Phase Shifts and the Doppler Effect
Authors: Michels Walter C.
Published: August 2005

If the path between a source S and an observer O is changed by an amount Δx, the phase of the wave received by O is shifted by Δn = −Δx/λ = −fΔx/c, where λ and f are, respectively, the wavelength and frequency of the disturbance and c is the speed of propagation, all measured by an observer fixed in the medium. The resulting change in observed frequency is Δf  = Δn/Δt, where Δt is the time taken for the observation of the phase change. It is shown that these two statements are sufficient for the derivation of the acoustic Doppler effect equations in all cases. The extension to the relativistic optical Doppler effect also follows if the Einstein time dilatation is taken into account.
ψ Superposition and Quantum Rules
Authors: Landé Alfred
Published: August 2005

The superposition rule for probability amplitudes ψ is not a separate ad hoc assumption of a physical character but is a formal consequence of the arrangement of the states of a system in sets of mutually orthogonal states linked by probabilities of transition. Nor do the quantum prescriptions of Born and Schrödinger have to be introduced as ad hoc assumptions; they can be deduced as consequences of (a) the superposition rule, and (b) the definition of conjugates q and p as leading to a constant probability density in qp-space, a quality known from classical statistical mechanics. Quantum theory can thus be deduced from a nonquantal background.
Using the Snooperscope with the Spectrometer
Authors: Dean D. E.
Published: August 2005

The adaptation of the snooperscope to the spectrometer is described. With it the elementary student may observe the near ultraviolet and infrared spectrum as an extension of the visible. The visible lines still show in their colors. Some of the better sources for spectral demonstrations are recommended. The “snooperscope spectrometer” is effective in demonstrating the shrinkage of the continuous spectrum with decrease in temperature of the source.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 72. Other Unrecorded Fifteenth-Century Paintings in which Spectacles Appear
Authors: Watson E. C.
Published: August 2005

This article calls attention to the fact that a fifteenth-century painting in which spectacles appear is to be found in the Fogg Museum of Art at Harvard University. Another unlisted painting of this type which hangs in the Art Gallery in Glasgow is also described.
Some Deterrents to Effective Teaching
Authors: Voeks Virginia W.
Published: August 2005

At the University of Washington, students of 284 classes anonymously rated their teachers on clarity of lectures, awakening of interest, and three other matters. At the end of the rating scale were spaces for comments. Over 90% of the students wrote comments. For the 57 teachers whose mean rating on the scale was either in the top 10% or the bottom 10% of the faculty, we made statistical analyses of the comments by their 1503 students.

The two groups of teachers appear to differ fundamentally in their conception of the students and, consequently, in their techniques of motivation. The low-rated teachers seem to be seriously out-of-touch with their students and to view them cynically. For example, these teachers frequently dwell upon the obvious, repeat the text or their lectures too much, ridicule the students, ignore questions, and use much sarcasm. The top-rated teachers apparently rarely or never do these things.

Other statistically significant differences between the two groups also are presented and discussed.
Secret of a Teacher
Authors: Stewart G. W.
Published: August 2005

A brief account is given of the teaching activities of Professor J. C. Jensen of Nebraska Wesleyan University during the last forty-five years. The story demonstrates how much can be accomplished with small financial resources if the teacher possesses energy, enthusiasm, and a lively interest in young people.
Improvement of Teaching as a Factor in the Production of Physicists
Authors: Buchta J. W.
Published: August 2005

The small number of physicists in training is a matter of national concern. The quality of the teaching of physics and the attention given the undergraduate students are here considered as factors contributing to the present difficulties.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 73. Portable Clocks and Watches in Early Paintings
Authors: Watson E. C.
Published: August 2005

Small portable clocks were in use at the end of the fifteenth century. Three interesting paintings now hanging in European galleries are here reproduced and the possibility that they portray such clocks is discussed.
Second Law of Thermodynamics Apparatus
Authors: Cole Malcolm B. , Ingersoll L. R.
Published: August 2005

Satisfactory laboratory apparatus—based on the electric refrigerator—for demonstration and quantitative work with the second law of thermodynamics has been devised and is now in use at the University of Wisconsin and the Missouri School of Mines and Metallurgy. The design and operation of the Wisconsin apparatus is described and the possible calculations discussed.
Useful Friction Recorder
Authors: Kurz Philip F.
Published: August 2005

A simple apparatus for recording frictional forces and changes in such forces encountered in traversing plane surfaces is described. Typical records are presented and the flexibility of the apparatus is discussed.
On Cerenkov Radiation
Authors: Balazs N. L.
Published: August 2005

In this paper Čerenkov radiation is treated using a generalization of Dirac's representation of the four potentials. This way the case of moving media can also be discussed.
Representation of Rotations in Three-Space by Complex 2×2 Matrices
Authors: Walker Marshall J.
Published: August 2005

A comparison is made between the representation of rotations in three dimensional space by real 3×3 matrices and complex 2×2 matrices. The relationship is used as a means of visualizing first-rank spinors.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 74. Fourteenth-Century Clocks Still in Existence
Authors: Watson E. C.
Published: August 2005

At least four mechanical clock mechanisms believed to have been constructed in the fourteenth century have survived to the present day. Two are in England (Salisbury and Wells), one in France (Rouen), and one in Germany (Nuremberg). Photographs of each are here reproduced and brief descriptions are given.
Teaching Performance
Authors: Hutchisson Elmer
Published: August 2005

An attempt is made in this paper to analyze the qualities that enter into good teaching. In making this analysis a parallel is drawn between performance measurement in the management field and that in teaching. Both contain highly emotional components which are difficult to measure. Both also contain components which can be measured and which are generally susceptible to improvement. Further analysis of the measurable components may require a joint study program by a large group of teachers and some suggestions are made for such a joint program. A better understanding of these components should result in better over-all teaching performance.
Experiment in Forced Oscillations
Authors: Henry Robert L.
Published: August 2005

A device for a quantitative experiment in forced, damped oscillations is described. The oscillator is a torsion pendulum driven by a variable speed motor and damped magnetically. Provision is made for reading the amplitude of the resulting steady-state oscillations, as well as the phase difference between the angular displacement and the driving torque. These directly measured values can then be compared with values obtained from theoretical expressions.
The Need for Trained Intelligence
Authors: Giddings Glenn W.
Published: August 2005

Three aspects of the need for highly intelligent trained people are discussed: the need for more understanding of some of the problems of education, the need for a more enlightened attitude on the part of industry in using trained intelligence, and the need for intelligent acceptance of our social responsibilities.
Johannes Kepler's Universe: Its Physics and Metaphysics
Authors: Holton Gerald
Published: August 2005

Though much neglected and misunderstood, Kepler was the first to attempt the detailed construction of a clockwork-like world picture operating on a single physical force law. An analysis of the eventual failure of Kepler's attempt gives us a clue to the central enigma in his writings: His heliocentric conception is a superposition of three aspects—physical, mathematical, and metaphysical. Kepler's free choice among these, which is the source both of his strength and of his apparent inconsistencies, results from his indecision between two different criteria of reality; according to one, the real world is the world of phenomena explainable by mechanical principles, and according to the other it is the world of harmonious regularity which man can discern by virtue of a direct connection existing between his mind and the Deity.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 75. Mechanical Clocks in Sixteenth-Century Art
Authors: Watson E. C.
Published: August 2005

By the sixteenth century mechanical clocks and watches were making frequent appearances in works of art. A number of examples are here reproduced.
Intermediate Laboratory Experiment in Physical Optics Using an Electron Microscope
Authors: Rood Joseph L.
Published: August 2005

An undergraduate laboratory experiment to study the magnification and limit of resolution of an electron microscope, appropriate to a physical optics course, is described. Polystyrene latex spheres of known diameter are used to obtain the magnification. The experiment introduces the student to some of the techniques of electron microscopy.
On a Certain Blindness in Physicists
Authors: Pierce W. M.
Published: August 2005

Shortages in people interested in science begin at the elementary level and continue at the secondary level for two fundamental reasons: inadequate teacher preparation and inadequate organization of curriculum materials. Solutions to the problem of shortages are being sought by physicists in the same tradition which has prevailed for the last fifty years, ignoring completely the changed high school conditions with which they must deal. Suggestions as to the lines of a possible solution other than the traditional one are indicated.
Remarks by Dr. Marsh W. White, February 2, 1956
Authors: White Marsh W.
Published: August 2005

Remarks made by the Chairman of the Committee on Awards for 1955 in presenting the medallist for the Oersted Medal, awarded to George E. Uhlenbeck, Professor of Physics at the University of Michigan, in recognition of notable contributions to the teaching of physics.
Reminiscences of Professor Paul Ehrenfest
Authors: Uhlenbeck G. E.
Published: August 2005

Remarks by Professor G. E. Uhlenbeck on the occasion of his receiving the Oersted Medal for notable contributions to the teaching of physics at the twenty-fifth anniversary meeting, New York, February 2, 1956.
Summary of Recent Measurements of the Compton Effect
Authors: Bernstein A. , Mann A. K.
Published: August 2005

The use of newly developed experimental techniques has led to the performance of experiments that have verified with relatively high precision both the assumptions and predictions of the quantum theory of the Compton effect. Several of these recent experiments, including some on the simultaneity of appearance of the scattered photon and recoil electron, the conservation of energy and momentum and the differential and total scattering cross sections, are briefly described. Their results are compared with those of earlier experiments and with theory to indicate the degree of severity with which the theory is presently tested.
Spectral Purity
Authors: Conn G. K. T.
Published: August 2005

Simple expressions are derived for the spectral purity of spectrometers of any slit width in terms of a variable α which expresses the angular slit width in terms of the diffraction pattern of the horizontal aperture. The range in wavelength embraced in the exit focal plane, Δλ = λ(α + h(α))/R, h(α) is the correction for diffraction and R is the Rayleigh resolving power. In terms of wave number this corresponds to Δv = (α + h(α))/(λR). These expressions are valid both for prisms and gratings. The form of Δv suggests that prismatic materials should be assessed according to a dispersive number dn/d logλ rather than the dispersion dn/dλ.
Magnetic Field Distributions for a Sphere and for an Ellipsoid
Authors: McClurg G. O.
Published: August 2005

The magnetic field distribution for a sphere in a uniform field is obtained by the usual method. This distribution is then transformed into the distribution for an ellipsoid in a uniform field by the method of conformal mapping.
Magnets for Resonance Work from Transformers
Authors: Broersma S.
Published: August 2005

With minor modifications, cutting and shaping one of the sides of the iron circuit, a core transformer can be made into a magnet. For example, one obtains a field strength of 6 kilogauss from such an electromagnet with a one-inch pole separation and a one-inch pole diameter. Using hollow pole pieces, it is possible to send a beam of microwaves through a paramagnetic sample placed between the poles inside a Dewar flask and to measure the microwave Faraday effect. The beam passes through the side walls of the oval-shaped flask. For 10 g of MnSO4·4H2O the absorption at the resonance point is 11, 26, and 30%; going through resonance the angle of rotation varies from plus to minus 1.9, 5.6, and 6.2 degrees for 290, 77, and 20°K, respectively.
Simple Model for Optical Activity
Authors: Chandrasekhar S.
Published: August 2005

The paper describes a simple theoretical model for explaining optical activity. The model consists of two anisotropic atoms, each having polarizability α. It is shown that when there is an assembly of such models, the refractive indices for right and left circular light are different, which means that the medium possesses optical rotatory power. By taking α to be complex in the vicinity of an optically active absorption band, the main features of Cotton effect or circular dichroism have also been explained.
Of Science and Politics
Authors: McReynolds John W.
Published: August 2005

The author would show that the political scientist is not sufficiently aware of what science qua natural science has done since the 16th century; that such an awareness is desirable at both the practical and theoretical levels of political enquiry; and that our colleges are capable of providing such an awareness, although they do not presently do so. He opposes “general education” programs, and proposes rigid course-work in fundamentals, including the calculus.
Some Applications of the Method of Dimensions to Atomic Physics
Authors: Conn G. K. T. , Crane E. E.
Published: August 2005

The analysis of problems by the method of dimensions is well known and has an important place in teaching, since successful application requires a clear understanding of the mechanism studied. Conversely it provides elementary and direct conclusions from particular assumptions or models. Application in the field of atomic physics seems to have been meager. This is unfortunate since not only are many expressions commonly derived by detailed analysis seem to be dimensionally essential but comparison is readily offered between classical and quantum physics. These matters are illustrated by considering a wide range of examples.
Statistical Approach to Spatial Measurement
Authors: Russell Allan M.
Published: August 2005

A method of determining length is described which reduces the measurement to a counting operation. The same technique is then applied to the measurement of flat areas and sections of the surface of a sphere. The limits of error are discussed and in particular the dependence of the error upon shape and the choice of a lattice is observed in the measurement of flat areas. Some possible applications are suggested.
Correlation between Grades in Engineering Physics and Performance in Engineering Curricula
Authors: Hoyt Donald , Ellsworth Louis D. , Katz Robert
Published: August 2005

A survey of grades in Engineering Physics I at Kansas State College showed that the inner structure of the course was highly consistent. The correlation coefficient between the average of the first three tests and the final grade was about 0.88. More significantly, valuable prognostic data could be obtained from the final grade in the course. The correlation coefficient between the Engineering Physics I grade and the final grade point average of students who completed the course was about 0.83. Only 21% of the students initially failing the course successfully completed an engineering degree, while about 75% of the A, B, and C students eventually graduated from an engineering curriculum.
Measurements on the Kerr Electro-Optical Effect
Authors: Jeppesen Myron A.
Published: August 2005

An experiment is described in which an inexpensive, commercially available cell is used. Values of the Kerr constant for nitrobenzene determined by this method are given for the spectral range from 4600 A to 8800 A.
Dynamical Principle for Classical Mechanics
Authors: Stehle P.
Published: August 2005

The dynamical principle underlying nonrelativistic classical particle mechanics is stated in a way which brings it into exact analogy with the quantum principle. The classical equations of motion for a dynamical variable are then displayed in forms analogous to the Schrödinger, Heisenberg, and interaction forms in quantum theory.
Teaching with the Polygraphe
Authors: Odier M. G.
Published: August 2005

Teaching physics with the aid of the Polygraphe, a recording milliammeter of great versatility, is a new teaching method rapidly developing in different French schools. In lecture demonstrations or in students' laboratory exercises this method provides graphs of great precision immediately usable for measuring purposes and for drawing curves of all sorts. In this paper, the psychological advantages of the Polygraphe as a teaching device are stated, and a few of its applications in elementary laboratory work are outlined.
Demonstration of Critical Phenomena for Pure Substances and Mixtures
Authors: Reamer H. H. , Sage B. H.
Published: August 2005

Appreciation of the physical characteristics of pure substances and mixtures in the vicinity of the critical state is difficult to obtain without direct observation. Demonstration equipment is described that permits the semiquantitative observation of the changes in state encountered during changes in volume of heterogeneous and homogeneous systems along a defined path in the vicinity of the critical state. The apparatus was so arranged that the appearance of the system and semiquantitative values of specific volume, temperature, and pressure may be projected on a screen for observation.
Demonstration of Electrical Transients
Authors: Rogers Douglas H.
Published: August 2005

A demonstration of electrical transients is described, intended for classes in elementary electricity, which yields a graphic illustration of the addition of the transient and steady-state terms in the solution of the equation for a ringing circuit under ac excitation.
Moments of Inertia of Solid Rectangular Parallelopipeds, Cubes, and Twin Cubes, and Two Other Regular Polyhedra
Authors: Satterly John
Published: August 2005

The derivation and verification of the values of the moments of inertia of simple solids such as rectangular blocks and cubes and combinations of two cubes and also of the regular polyhedra afford good exercise in theory and practice. The formulas lead readily from one to the next. The verification of the values obtained have been made with a torsion wire and frame plus a good stopwatch, and has afforded many hours of quiet pleasure.
Precession of a Gyro and Model of a Gyro-Compass
Authors: Scott G. David
Published: August 2005

Two aids to the teaching of gyroscopic motion are given: (1) the precession of a gyro is discussed as a rotational analogy to the case of a stone whirling on the end of a string; (2) precession is explained qualitatively in terms of linear dynamics. As an example of precession a north-seeking gyro-compass is considered and a model described which illustrates its behavior.
Squirting Manometer
Authors: Green John R. , Thomas Roy
Published: August 2005

An analysis is made of the process of emptying a full, open manometer by increasing the pressure at the closed side until the liquid is contained only in the open side, filling the tube; a slight increase in pressure will then result in an explosive eruption of the liquid.
On Phase Transformations
Authors: Fischer Gaston
Published: August 2005

The aim of the following work is to clarify the definitions of the order of phase transformations, in the case of systems composed of only one substance. First- and second-order phase transformations are discussed with the help of geometrical arguments applied to the intersection of free energy functions. This method also enables us to analyze the behavior of quantities such as the specific heat. As an application, second-order phase transformations of ferroelectric substances are discussed in some detail.
Effective and Inexpensive Slits for Teaching Physical Optics
Authors: Chapman Seville , Meese Harold
Published: August 2005

A discussion is given of how sets of single, double, and multiple slits may be made for use in lecture demonstrations in physical optics courses where each student has his own set of slits through which a source is viewed with the naked eye. Very careful work is required with very high-grade photographic equipment.
Didactical Absolute Viscosimeter
Authors: De Smedt J. , De Bock A.
Published: August 2005

A didactical apparatus for the absolute measurement of small coefficients of viscosity (1 centipoise) with an accuracy of 1%is presented. A W-shaped piece rotates about a vertical axis at a variable distance from the walls of an identically shaped vessel, containing the liquid sample. A wire wound on a drum attached to the axis, carries a mass, which accelerates the rotor when falling through a distance H in the time interval T. When completely unrolled the wire is rewound on the drum and the mass is lifted up to a smaller height H′ in a shorter time T′. The determination of both distances and time intervals permits calculation of the coefficient of viscosity.
Horizontal Pendulum with Variable Modulus of Torsion (Resonance Curve)
Authors: De Smedt J. , De Bock A.
Published: August 2005

A didactical apparatus for accurate determination of resonance curves is presented. A bifilarly suspended disk, whose natural period is variable between large limits while the system is oscillating, is suited for easy determination of a resonance curve, because the period of the forced oscillation can remain unchanged during operation. The rigidity and hence the natural period of the pendulum is altered by a change in the mass supported by the bifilar suspension; this is done by means of a third axial wire, from the disk to a yoke carrying counterweights.
Beta Spectroscopy Using a Diffusion Cloud Chamber
Authors: Silvidi Anthony A.
Published: August 2005

The quantitative usefulness of an inexpensive chamber particularly adaptable for small colleges is shown. In particular, the beta spectrum of Pm-147 was obtained and compared with the spectrum which had been obtained by the use of an intermediate-image type spectrometer. The end-point energy as obtained here is 231 kev for a difference of 3.5% as compared with published values of 223 kev.
Proportional Counters for Demonstration Experiments
Authors: Moljk A. , Drever R. W. P.
Published: August 2005

Proportional counters suitable for demonstration purposes are described, and some experiments to illustrate counter operation are discussed. The charge carried by the positive ions produced in the multiplication process, and the localization of the avalanche, is revealed in a special proportional counter whose cathode is covered by a layer of polythene. Other properties of this type of counter, such as its ability to work for a considerable period of time without a high-voltage supply, are pointed out.
Physics and Physical Science in New Orleans, 1800–1860
Authors: Riess Karlem
Published: August 2005

A survey of the early developments in physical science in New Orleans, with emphasis on the important contributions of John Leonard Riddell, Edward Hall Barton, Claudius Wistar Sears, and Caleb G. Forshey.
On a Space-Time Representation of Nonrelativistic Wave Mechanics
Authors: Armstrong H. L.
Published: August 2005

A space-time representation is developed for nonrelativistic wave mechanics as was done for classical mechanics, by adding to the system a rotating body to serve as a clock, and applying the time-independent forms of the equations of motion. The usual Schrödinger equation is obtained in this way, however, only in the limit as the energy of the clock becomes very large. The reason for this restriction is found in an appendix, by comparison with the classical equations. Other appendices deal with certain aspects of the Hamiltonian representation of the problem.
Generalizations of the Virial Theorem
Authors: Schectman R. M. , Good R. H.
Published: August 2005

This paper is a review of three generalizations of the classical virial theorem of Clausius, the first to a continuous distribution of charge and mass moving with relativistic velocity and its associated electromagnetic field, the second to a single Dirac particle in an external electromagnetic field, and the third to a quantum-mechanical system of particles in a box. Various limiting cases are discussed and tensor versions of the theorem are given where applicable.