bluuebunny/crossref_metadata_2025 huggingface dataset:
A Laboratory Experiment with Coupled Linear Oscillators
Authors: Miller Franklin
Published: August 2005

Two rolling masses and three helical springs are arranged collinearly in a horizontal plane. Longitudinal vibrations of the system are excited manually and the two normal modes studied. Calculated and observed frequencies can be compared in detail, since the coupling constant is directly measured. Agreement is obtained to within a few percent.
Selection Rules for Vibrational Spectra of Linear Molecules
Authors: Ferigle Salvador M. , Meister Arnold G.
Published: August 2005

An elementary explanation is given of the group theory method using characters to determine the selection rules for the fundamental vibrations of a linear polyatomic molecule. Then the method is extended to indicate how the selection rules for the overtones and summation and difference tones are obtained. Finally, the procedure for determining the number of fundamental frequencies belonging to a particular vibration type is given. The groups C∞v and D∞h are used as examples in the treatment since they are the only ones involved in the consideration of linear molecules.
Integration as an Objective in the Physical Sciences
Authors: Barbour Ian G.
Published: August 2005

The educational objective of integration or “insight into relationships of one's own field to other areas of life” is discussed. Several types of general education science course are compared in their attempt to present science in relation to other fields of human knowledge. A two-week unit is outlined dealing specifically with the impact of science on man's life and thought.
The Eckart Conditions for a Polyatomic Molecule
Authors: Ferigle Salvador M. , Weber Alfons
Published: August 2005

The Eckart conditions for a polyatomic molecule are discussed. They are introduced to insure the smallness of the interaction between vibration and rotation and define a system of coordinates in which the vibration of the atoms around their equilibrium positions is described.
Čerenkov Radiation in a Dispersive Medium
Authors: Motz H. , Schiff L. I.
Published: August 2005

Attention is called to the disagreement between a recent statement of Sommerfeld that the direction of propagation of Čerenkov radiation in a dispersive medium is determined by the group velocity, and the generally accepted result that the phase velocity must be used. The latter is shown to be correct, and the role of the group velocity is discussed in a way similar to that given in Tamm's 1939 paper on the theory of the Čerenkov radiation.
The Tippe Top (Topsy-Turvy Top)
Authors: Pliskin William A.
Published: August 2005

Two fundamentally different explanations have been given in the literature to explain the “unusual” motion of a specially constructed spherical top in which rotation causes the center of gravity of the top to rise, the top turning 180° and finally spinning on its stem like an ordinary top. This independently derived analysis shows that the force due to sliding friction is in such a direction as to result in a torque which causes the angular velocity components to vary in a way which necessitates the rising of the center of gravity. This analysis, which emphasizes the physical picture behind the phenomenon, agrees with two previously published papers that friction plays the primary role. Some experimental evidence is given to support the present analysis.
Integrability Conditions and Carathéodory's Theorem
Authors: Buchdahl H. A.
Published: August 2005

The theorem of Carathéodory is proved by showing that the necessary and sufficient condition for the existence of points neighboring to an arbitrary point which are inaccessible from the latter along solution curves of a linear total differential equation is that the conditions of integrability of the equation be satisfied.
The Theory of Vector Spherical Harmonics
Authors: Hill E. L.
Published: August 2005

Differential equations involving vector fields expressed in terms of spherical polar coordinates are readily manipulated by the use of vector spherical harmonics. The explicit definitions of these functions and a sufficient set of formulas for easy calculation are given.
Physics of the Glassy State. IV. Radiation-Sensitive Glasses
Authors: Condon E. U.
Published: August 2005

Effects of radiation in producing color changes, often called solarization, in glass are described, in close analogy with modern work on F centers especially in alkali-halide crystals. Photosensitive glasses in which the action of radiation is to produce centers of nucleation around which colloidal or crystalline precipitates can form are also discussed.
Measurement of Laboratory Achievement. Part III. Paper-Pencil Analogs of Laboratory Performance Tests
Authors: Kruglak Haym
Published: August 2005

An attempt has been made to convert laboratory performance tests into essay and multiple-choice items. Preliminary forms of the tests were administered to about 160 elementary physics students. It was found that the multiple-choice was the least difficult of the three tests; the performance, the most difficult. The correlation coefficients between relatively complex performance items and their paper-pencil analogs were very low. The correlations between the items dealing with specific skills and parallel paper-pencil tests were low to moderate. The preliminary study supports the hypothesis that paper-pencil tests are poor substitutes for performance examinations.
Some Comments on the Nature of Physical Theory and Their Theoretical and Pedagogical Implications
Authors: Barthel Romard
Published: August 2005

An analysis of the nature of physical theory brings out the rational origin of some of the fundamental principles of modern physics and makes clearer the proper attitude of physicists toward their science. The pedagogical importance of this analysis is accentuated.
Conversion of Solar to Electrical Energy
Authors: Pearson G. L.
Published: August 2005

A photovoltaic device has been developed which converts solar radiation directly into electrical energy with an over-all efficiency of 11%. This consists of a p-n junction formed by gaseous diffusion near the front surface of a silicon plate. In full sunlight a single cell furnishes approximately 30 ma of short circuit current per square centimeter of surface, 0.6 v of open circuit voltage, and 12 mw of power into a matched load per square centimeter of surface. Like other electric batteries, individual cells may be connected in series or parallel to obtain an increase in terminal voltage or current. The spectral response is a maximum near 0.7 µ, and the long wavelength cutoff is at approximately 1.1 µ. The efficiency of this new silicon p-n junction photovoltaic cell is greater by a factor of 20 than that previously reported for other types of photocells and makes the conversion of the sun's energy directly into electricity possible for a number of interesting applications. A Bell System field trial at Americus, Georgia, in which solar batteries are used to power a rural carrier telephone communication system, is described. A number of other possible applications for this new solar energy converter are discussed.
Ampere's Law and the Vector Potential
Authors: Raff S. J.
Published: August 2005

Some general features of several elementary methods of determining the magnetic field of a current configuration are examined. Ampere's law, the circuital form of Maxwell's equation and a derived relation between the magnetic field and the vector curl of the current, are each applied to the simple problem of computing the magnetic field due to a thin current dipole in a conducting medium. The significance of closed current paths and the conditions under which the return currents in the medium must be included in the computation are discussed for the dc case.

The conclusions concerning dc currents are then considered in relation to ac problems and the use of the vector potential in antenna problems. These considerations indicate why only antenna currents enter into the computation of vector potential and the nature of the “thick antenna” problem.
Laboratory Measurement of the Velocity of Light
Authors: Alford W. Parker , Gold Albert
Published: August 2005

An experimental method is presented for a reasonably precise, direct measurement of the velocity of light using simple apparatus. The method is based on the result that the Fourier transform of a pair of identical pulses yields a frequency spectrum with zeros which are simply related to the time separation of the pulses. The principal pieces of apparatus required for the experiment are a photomultiplier and high-voltage power supply, and a short-wave radio receiver. With this relatively simple equipment and path lengths of fifty to one hundred feet, c may be readily measured to an accuracy of 1% or better.
New Look at von Neumann's Operator Method in Quantum Statistics. II
Authors: Band William
Published: August 2005

In this second part of the paper, the quantum-mechanical equation of change with time is applied to an ensemble, and the quantum-mechanical analog of the classical Liouville theorem is derived. The conflict between the quantum-mechanical equation of change of an isolated system, and the second law of thermodynamics is explained. The connection between entropy and the uncertainty principle and the effect of measurement on entropy are discussed in detail. It is pointed out that in quantum mechanics, the uncertainty principle forbids the complete specification of the boundaries of a truly isolated system. The effects of random disturbances at the boundary, within the limits permitted by the uncertainty principle, are shown to cause a rapid spontaneous approach to maximum entropy of any “isolated” system. Applications to quasi-stationary irreversible effects are briefly discussed, and it is indicated how the concept of random fluctuations of the boundary leads to a deduction of the Fokker-Planck equation for irreversible processes.
Laboratory Courses for Physics Majors
Authors: Plint Colin A.
Published: August 2005

Some problems associated with the conventional laboratory courses are discussed and details of a new laboratory program at the University of Oklahoma presented. The new program has proved highly successful after two year's operation.
Experiments with Modified Form of Simple Pendulum
Authors: Fox J. W.
Published: August 2005

A bob is hung by a Y- or V-shaped thread and oscillates in a plane normal to that defined by the equilibrium position of the thread. A variation of period is achieved by moving apart the two points of suspension. Simple theory is given and is illustrated by experimental results.
Structure of Uniform Liquids
Authors: Cole G. H. A.
Published: August 2005

Calculations of the properties of classical liquids are, at the present time, based upon a detailed and accurate knowledge of the distribution of pairs of molecules within the liquid. In the present paper the reasons for this are explained, and the methods so far proposed for obtaining the necessary information for equilibrium conditions are explored.
Molecular Models: Expressions of the Transport and Virial Coefficients
Authors: McMillan Juan A.
Published: August 2005

A review of the transport and the virial coefficients from the point of view of their expressions as derived from rigid sphere, Sutherland, inverse power, and Lennard-Jones models is given. The assignment of the interaction behavior from viscosity data is discussed.
Klein Paradox for the Klein-Gordon Equation
Authors: Winter Rolf G.
Published: August 2005

The behavior of a beam of spin-zero particles incident on a region of large potential increase is examined. The results are compared with those obtained from similar computations employing the Dirac equation. This comparison yields an instructive illustration of the difference between particles and antiparticles in spin zero and spin one-half single-particle theory.
Lunar-Solar Perturbations of an Earth Satellite
Authors: Blitzer Leon
Published: August 2005

The influence of the sun and moon on the orbit of a near satellite of the earth is investigated, and it is shown that the principal effect is a precession of the orbit plane about the pole of the ecliptic, analogous to the precession of the equinoxes. The precessional rate increases with orbit size and eccentricity and decreases with orbit inclination to the equator. For orbits close to the earth the lunar-solar precessional motion is only about 10−4 that due to the earth's oblateness. Radial perturbations resulting from the attractions of the sun and moon are similarly extremely small, being of the order of one meter. The induced radial oscillations exhibit twice the frequency of the satellite's orbital motion around the earth, analogous to the twice daily motion of the tides. To second-order terms in the orbit eccentricity the expressions derived herein are in exact agreement with the astronomical treatments for the special case of the perturbations of the moon's orbit due to the sun.
Classical Interaction of an Electric Charge with a Magnetic Monopole
Authors: Lapidus I. Richard , Pietenpol Jerry L.
Published: August 2005

The motion of a charged particle in the field of a magnetic monopole is calculated classically. The differential scattering cross section is obtained, and it is seen that in the limit of small interaction strength the cross section resembles the Rutherford cross section. A simple relativistic correction is discussed.
New High-Vacuum Technique: Kits to be Used by Students to Make Vacuum Tubes
Authors: Harries J. H. Owen
Published: August 2005

In order to teach modern microphysics successfully it has been found necessary for the students to make their own vacuum tubes. But making vacuum tubes by standard techniques involves an expenditure on equipment of many thousands of dollars and the services of highly skilled technicians. A research program has been carried out which resulted in a technique whereby students can make their own vacuum tubes by using a Meccano-like kit of parts at a cost of a few tens of dollars per kit. No skilled technicians are necessary and high vacua (10−7 to 10−8 mm Hg) are obtained without the customary precautions as to cleanliness and without costly equipment. Two methods of exhaust are used: (1) A method using activated charcoal, CO2, a special gettering regime, and a vacuum gauge. (2) A method using a mechanical pump with the same gettering regime and vacuum gauge. A students' kit has been designed and exhibited. Some classroom experiments have been demonstrated. The vacuum technique and kits have applications in research and industry as well as in teaching. This project is being carried out at the request of Professor Jerrold R. Zacharias in connection with the new physics course of the Physical Science Study Committee of Educational Services Inc.
Introduction to Geomagnetism: The Equatorial Electrojet
Authors: Casaverde Mateo
Published: August 2005

The fundamentals of the measurement of the earth's magnetic field are described. The general form of the geomagnetic field is approximated to the field of a theoretical dipole magnet. The solar daily type (S) of transient variation in the geomagnetic field depends on the solar activity, the seasons, the geographical latitude, and local time. At Huancayo Magnetic Observatory the abnormally high daily variation of the horizontal component of the geomagnetic field at the magnetic equator was discovered. This variation is confined to a narrow belt around the magnetic equator due to an induced effect of the equatorial electrojet.

This equatorial electrojet is an eastward flowing current in the atmosphere at about 100 km altitude, some 660 km wide, with a measured maximum current density of as high as 140 amp/ km of width, for a given time. The theory of the origin of the electrojet developing from an increase in atmospheric conductivity at the equator and winds at high latitudes is described. Finally, the quiet-day solar daily variation in the vertical component of the geomagnetic field in the magnetic equatorial region in Peru is presented tentatively as a combined effect of the normal upper atmospheric current flow and the electrojet. A bibliography is included.
The Scattering of X Rays as Particles
Authors: Compton A. H.
Published: August 2005

The experimental evidence and the theoretical considerations that led to the discovery and interpretation of the modification of the wavelength of x rays as a result of scattering by electrons are reviewed, as is the controversy between Duane and the author that took place in 1923–24. The confirmatory evidence obtained by Bothe, Geiger, Simon, and Compton is summarized.
An Unusual Method of Solving the Harmonic-Oscillator Equation
Authors: Weinstock Robert
Published: August 2005

The differential equation of the harmonic oscillator is solved by a method that employs techniques of the elementary calculus only.
Limit of a One-Dimensional Square Well
Authors: Brennan James G.
Published: August 2005

A wave function which represents a decaying exponential in all space is shown to be the limiting solution to a one-dimensional square well potential problem. If the limit is defined properly, the expectation value of the kinetic energy is shown to be positive definite.
Distribution of Time in General Physics Courses
Authors: White Marsh W.
Published: August 2005

Because of the steadily increasing number of students in the general physics courses and the shortage of teachers, many physics departments are searching for methods of handling larger numbers of students per section. About 100 of the larger physics departments were queried to obtain information concerning their methods for handling these classes. The data received indicate considerable variations in the distribution of class hours between recitation, lecture, and laboratory. There is some evidence of a trend toward more hours per week in larger lecture groups, with fewer hours devoted to recitation sections. The time devoted to laboratory work has been slightly reduced in these courses in recent years.
Thermodynamics, Statistics, and Information
Authors: Brillouin L.
Published: August 2005

A short summary of the two principles of thermodynamics, together with the statistical interpretation of entropy, is given. It is shown that the definition of “information” leads to a direct connection between information and the negative of entropy (abbreviated: negentropy). Every experiment consumes negentropy (increases entropy) and yields information. The negentropy principle of information is a generalization of Carnot's principle, and is explained on different examples. The informational value of physical laws is discussed and the role of creative thinking emphasized.
Measurements of a Magnetic Field
Authors: Zucker Charles
Published: August 2005

A method for measuring the average value of the magnetic field between pole pieces of a fixed magnet using a current-carrying wire has been developed. This method vividly demonstrates the interplay of electromagnetic and mechanical forces and allows for the measurement of the average magnetic field.
Plasma Resonance in the Electrodynamics of Metal Films
Authors: Ferrell Richard A. , Stern Edward A.
Published: August 2005

When a fast electron passes through a thin metal film it can excite plasma oscillations which then re-radiate the energy in the form of photons. The emitted radiation will appear in a more or less sharp spectral line whose width is the sum of the intrinsic damping rate and the radiative natural line breadth. A completely equivalent formalism is provided by the extension of the theory of transition radiation (semi-infinite metal), to the case of a slab of metal bounded by two parallel planes. In the ideal case of a metal whose dielectric constant contains only a real lossless part, and no imaginary absorptive part, the predicted breadth and strength of the spectral line are the same in both theories. A further phenomenon which is suggested by the plasma-oscillation point of view is the possibility of a resonance in the reflection coefficient of a thin metal film at the plasma frequency, brought about by the collective response of the conduction electrons. The height and breadth of this resonance have been computed and should be observable in relatively ideal cases.
A Student Measurement of the Diffusion Length of Thermal Neutrons in Water by a Negative Source Technique
Authors: Bretscher M. M.
Published: August 2005

A student experiment designed to measure the diffusion length of thermal neutrons in water is described. The technique requires only simple apparatus, demonstrates the fundamental aspects of neutron diffusion, and yields results in good agreement with the literature. Using this method the diffusion length was found to be 2.80±0.04 cm.
The Macroscopic Nature of Space-Time
Authors: Zimmerman E. J.
Published: August 2005

Current interpretations of quantum mechanics suggest that the classical concepts of space and time are not applicable to microscopic systems. Salecker and Wigner have recently proved that these concepts have no operational meaning for microsystems. Therefore, space-time descriptions may be valid only for macroscopic systems. It is here suggested that space and time themselves arise from, but do not have analogs in, the properties of microscopic particles, in the same way that thermodynamic properties arise as a result of interactions among the many actually existing particles of the universe. Neither the particles nor the interactions need to be described in spatial-temporal terms. This macroscopic interpretation of space-time seems compatible with the known properties of the physical world, suggests a more direct interpretation of the statistical nature of microscopic events, and offers a new approach to some physical problems.
Preparation for Teaching Physics in Secondary Schools
Authors: Watson Fletcher G.
Published: August 2005

College physics instructors may well question whether their traditional lack of attention to the preparation of teachers is not an evasion of responsibility. In particular, they may ask whether they are giving sufficient attention to the achievement by the student of an understanding of science. Recently suggested or proposed changes in certification requirements fail to recognize the essential fact that almost all high school science teachers must teach two or more different sciences, and it appears certain that basic changes in curricula, rather than the prescription of certain traditional courses, are needed if we are to prepare teachers of the tenth through twelfth grades.
A Simplified Simplification of Carathéodory's Treatment of Thermodynamics
Authors: Sears Francis W.
Published: August 2005

The generality of Carthéodory's treatment can be retained if one considers a composite system whose state is defined by only three variables. Carathéodory's axiomatic approach is rendered less abstract by discussing a specific system, and by supplementing a purely analytic treatment with appropriate diagrams.
Electromagnetic Levitator
Authors: White Harvey E. , Weltin Hans
Published: August 2005

This paper describes the construction of an electromagnetic levitator whose small size makes possible the use of easily obtainable surplus capacitors, and puts the levitator within the skill and the budget of even a modest physics department shop.
“Slide Rule” for Complex Numbers
Authors: Hetherington J. H.
Published: August 2005

A method for carrying out complex arithmetic which is completely analogous to the principle of the ordinary real number slide rule is described. The method results from the observation that the two basic principles of the slide rule, the equivalence of the logarithm of a product to the sum of logarithms and the addition of lengths by sliding rules, may both be extended to the complex plane. An actual device and several possible variations are discussed.
A Method for Measuring the Sound Wavelength in Gases
Authors: Lestz S. S.
Published: August 2005

A method for measuring the wavelength of sound in a gas, confined in a tube, by means of phase measurement is described. The basic method was first proposed by G. Patchett for free air determinations in 1943, and a similar procedure was described by V. Hovi in 1959. The advantages of the method and associated equipment are simplicity and high accuracy. Results for dry CO2-free air and nitrogen at room temperature and atmospheric pressure are given. The form and use of the tube correction is illustrated.
Formalized System of Equations in Electromagnetism
Authors: Venkates H. G.
Published: August 2005

General principles involved in setting up unit systems of physics have been briefly indicated. The paper, intended as a contribution to teaching, is in the main concerned with the application of these principles in electromagnetism. Formalized equations (explained in the paper) have been set up, from which coherent unit systems including the well-known systems of electromagnetism, could be derived as special cases. Some arguments are presented for the adoption of the formalized system. Its advantages result from the introduction into the field equations, now regarded as quantity equations of a symbolic algebra, four parameters which enable one to define units and dimensions and, moreover, to redefine physical quantities consistently for the purpose of rationalization. The most important relations between electromagnetic quantities in the formalized system have been given. Conversion formulas have been derived for all the quantities occurring in the field equations illustrating one of the advantages of the formalized system, namely, the facility of transformations.
Lagrangian Solutions of the Equations of Motion in Fluid Mechanics by Integrating Certain Types of Nonlinear Ordinary Differential Equations
Authors: Ruei K. H.
Published: August 2005

The classical problems of the forced motion of a fluid particle induced by the motion of solid bodies immersed in an incompressible and nonviscous fluid of unbounded extent are solved by integrating nonlinear equations of the type: (d2r/dt2) + P(r,t)(dr/dt)3 + Q(r,t)(dr/dt)2 + R(t)dr/dt = 0, and (d2r/dt2) + M(r)(dr/dt)2 + N(r,t)dr/dt + S(r,t) = 0. The solutions of the Lagrangian equations of motion instead of the usual Euler's equations furnish better physical insight. The second integrals are evaluated in terms of both elliptic integrals and series for the problem of cylinder, and hyperelliptic integrals and series for the sphere. A systematic method of integrating nonlinear equations of this type is discussed. The problem of a half-body is also discussed.
Centripetal Force Apparatus
Authors: Weltin Hans
Published: August 2005

At the expense of only a few cents, and with equipment available in every physics laboratory, an experiment on centripetal force has been assembled, which may represent the ultimate in simplicity. The accuracy of the results is as good as, or exceeds that of centripetal force apparatus sold at high prices.
Resource Letter QSL-1 on Quantum and Statistical Aspects of Light
Authors: Carruthers P.
Published: August 2005

Prepared at the request of the AAPT Committee on Resource Letters.

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

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

Additional copies: Available from American Institute of Physics, 335 East 45 Street, New York 17, New York. When ordering, request Resource Letter QSL-1, and enclose a stamped return envelope.
Heat Waves and Ångström's Method
Authors: Bryant Howard C.
Published: August 2005

The study of the propagation of a fluctuating temperature along a copper rod proves to be an instructive experiment for our junior-senior laboratory. Temperatures are measured as a function of time and of distance along the rod; one end of which is periodically heated and cooled, while the other end is kept at constant temperature. The temperature distribution is that of a traveling wave, each frequency component of which damps out with a characteristic distance that decreases with increasing frequency of the component. From a determination of the velocity and characteristic damping distance of the fundamental, the student calculates the thermal diffusivity of copper.
Francis Lee Friedman: Oersted Medalist for 1962
Authors: Correll Malcolm
Published: August 2005

Remarks made by the Chairman of the Committee on Awards for 1963 during the presentation ceremony of the Oersted Medal, posthumously, to the late Francis Lee Friedman in recognition of his notable contributions to the teaching of physics
Insight and Taste
Authors: Morrison Philip
Published: August 2005

Response in Memory of Francis Lee Friedman, Oersted Medalist, to the American Association of Physics Teachers, 25 January 1963.
Resistance to Ohm's Law
Authors: Schagrin Morton L.
Published: August 2005

It is argued that the usual account of the discovery and subsequent rejection, or criticism, of Ohm's law is both a misleading and an inadequate explanation. A close logical examination of Ohm's experimental work reveals a conceptual structure quite different from that of the electrical science of his time. As a result of this analysis, it is claimed that the conceptual shift in Ohm's experimental work was the basis for the reaction of his contemporaries.
Levinson's Theorem (an Elementary Derivation)
Authors: Wellner Marcel
Published: August 2005

If a spherical potential admits n bound states with a certain angular momentum, then Levinson's theorem states that δ(O) − δ(∞) = nπ, where δ(E) is the scattering phase shift (corresponding to that angular momentum) as a function of energy. This is shown here by means of elementary wave mechanics.
Coherence and Fluctuations in Light Beams
Authors: Martienssen W. , Spiller E.
Published: August 2005

A quasithermal, quasmonochromatic lamp is described which serves as a highly degenerate light source with adjustable coherence time between 10−5 sec and 1 sec. This lamp is used for several demonstration experiments concerning the relations between coherence and fluctuations: The intensity interferometer of Hanbury Brown and Twiss is applied to measure the correlations between intensity fluctuations. The double slit experiment of Young serves to stress the role of fluctuations for classical interferometry. Interference patterns from two independent quasithermal lamps are presented.
Constraints in the Q-T-P-H Space of States and Energy
Authors: Shankland Donn G.
Published: August 2005

Dirac's treatment of constraints is reformulated in the Q-T-P-H space of states and energy. The approach affords a symmetric method of introducing constraints and testing their compatibility. When they are not compatible, one is led to Dirac's classification into first- and second-class constraints. When they are compatible, i.e., all first class, the transition to quantum mechanics is immediate.
Remarks on the Theory of Measurement
Authors: Yanase M. M.
Published: August 2005

A new classification of quantum mechanical quantities according to their measurability is discussed. We have three different types of quantities: first, exactly measurable quantities which commute with all the conserved quantities; second, approximately measurable quantities which do not commute with all additive conserved quantities; and finally nonmeasurable quantities which are conjugate to the absolute invariants. The epistemological implications of the measurement process are discussed and it is pointed out that the quantum mechanical description of this process does not furnish an adequate explanation of the acquisition of knowledge.
A Laboratory-Techniques Course for Physics Students
Authors: Hart John , Hafner Karl F.
Published: August 2005

A successful Laboratory-Techniques course, consisting of about 80 h in the workshop and laboratory, is outlined. The course is suitable for Pass and Honors physics students in their junior year.
Some Comments on Entropy and Information
Authors: Rodd Philip
Published: August 2005

Information is quantitatively defined in terms of probability, and the statistical interpretation of entropy is given. Entropy change and information are shown to be related on a physical basis, treating a simple volume expansion as an example. Maxwell's demon is discussed as an example of an irreversible process. The argument used by Brillouin in his discussion of the demon is corrected. A generalized second law of thermodynamics is set forth.
A Student Experiment in Fresnel Diffraction
Authors: Young Paul A.
Published: August 2005

An experiment in Fresnel diffraction is described suitable for third-year physics students, that emphasizes some of the numerical, as distinct from the purely observational, aspects of diffraction at a circular aperture.
Spring-Mass Correction in Uniform Circular Motion
Authors: Weinstock Robert
Published: August 2005

A detailed analysis is presented for the problem of uniform circular motion in which the centripetal force is provided by a stretched spring whose mass is not negligible compared with that of the whirling body. It is shown that the force required to stretch the spring statically to the length it has during the rotation exceeds the centripetal force it exerts on the whirling body by an amount depending in a simple way on the spring mass; the excess can be erased by adding to the body mass approximately one-third the spring mass in computing the centripetal force. Some experimental results that tend to support the theory are exhibited and discussed. A computation of radial-oscillation frequencies is included.
Brief Review of Ultrasonic Attenuation with Some Emphasis on Work at Ultrahigh Frequency
Authors: Dignum R.
Published: August 2005

A discussion is given of the methods that have been used in ultrasonic attenuation studies, with block diagrams of several experimental setups. Sources of internal friction in metals are mentioned and a brief discussion of magnetoacoustic measurements is given. Measurements on nonmetallic crystals and glasses at gigacycle frequencies and the amplification of ultra sound in semiconductors are briefly considered.
Semiclassical Theory of Infrared Divergence
Authors: Belinfante Johan G.
Published: August 2005

A great deal of insight can be obtained into the infrared divergence problem in quantum electrodynamics by consideration of a simple model in which the electromagnetic field is quantized but the electric current is treated classically. It is not necessary to use box normalization.
Electromagnetic Behavior of the Vortex Sponge
Authors: Kelly Edward M.
Published: August 2005

In an introductory paper, the vortex sponge was shown to be governed, in restricted cases, by Maxwell's free-space equations. In the present paper, analogs to electric and magnetic energies and Poynting's theorem are derived by simple mechanical considerations. Rotational stability, suggested originally by MacCullagh as a fundamental property of a luminiferous ether, turns out to be a quality of the medium, as do the stresses introduced by Faraday and Maxwell to explain the mechanical actions of electric and magnetic fields. A rudimentary model for the electrostatic field is suggested on this basis. A conventional definition of charge and the laws of Coulomb and Biot complete Maxwell's equations for cases including charges and currents. A model of the magnetic field based on the bulk rotation and the Faraday-Maxwell stresses, combined with the laws of Coulomb and Biot, permits the inference of the Lorentz force. Although numerous gaps occur in the treatment, it seems not unlikely that the vortex sponge has the qualities described by the electromagnetic field equations as well as the mechanical attributes required for a model of these fields.
Energy Equipartition: A Restatement
Authors: Lawless W. N.
Published: August 2005

In order to explain energy equipartition in terms of temperature changes, the equipartition theorem is restated to incorporate the kinetic-theory definition of temperature. This procedure emphasizes the role of energy changes in a system and thereby promotes a clearer understanding of, and the need for, the quantum partition case.
Two Quantitative Lecture Demonstrations concerning Linear Momentum
Authors: Shrader Erwin F.
Published: August 2005

Two quantitative lecture demonstrations are described. The first uses a water jet to illustrate the relation between the reaction thrust and the time rate of change of momentum in the jet. The second demonstration uses an air trough with a conceptually simple but quantitative method for measuring the velocities of the air trough gliders. Conservation of momentum can be quantitatively verified in a variety of elastic and inelastic collisions. In both demonstrations accuracies of one or two per cent are easy to obtain.
Single-Concept Films in Physics
Authors: Miller Franklin
Published: August 2005

Short films are described which are designed to be used within a teacher's lecture, having application at various levels of instruction. The importance of the teachers' guide is stressed. Commercial distribution of the series is on a nonexclusive basis. New projectors and film formats are described. An annual competition is proposed for short 8mm films made by physics teachers for use in their own classes.
Differentiating Orthogonal Unit Vectors with respect to Curvilinear Coordinates
Authors: Kijewski Louis J.
Published: August 2005

The identity δ2R/δUiδUj = δ2R/δUjδUi is used to obtain a simple heuristic derivation and also an exact derivation for derivatives of unit vectors in n dimensions. Only an expression for δei/δUj (i≢j) is obtained by this method, but δei/δUi may be expressed in terms of δei/δUj (i≢j) and thus in terms of the unit vectors ek.
Hertz's Derivation of Maxwell's Equations
Authors: Zatzkis Henry
Published: August 2005

Heinrich Hertz has shown how Maxwell's equations can be derived by a process of successive approximations from the earlier action-at-a-distance theory. The method has a certain similarity with the Picard method of successive approximations. A mathematical error in Hertz's paper is corrected. The historical significance of Hertz's paper is stressed.
Elementary Derivation of the Thermal Motion of Galvanometers
Authors: Smith W. E.
Published: August 2005

An elementary derivation of the spectrum of the thermal motion of a galvanometer is obtained by adapting the Nyquist argument for electrical noise. The results are quite general for rotary motion and may be extended to other mechanical systems by the use of further electromechanical analogies.
Simplified Experiment Demonstrating Interstitial Diffusion in Alpha Iron
Authors: Mortlock A. J.
Published: August 2005

An experiment is described which demonstrates the diffusion of interstitial impurities in alpha iron. It consists in the measurement of the logarithmic decrement of the oscillatory motion of a torsional pendulum utilizing a commercially available iron suspension wire of high purity. From the results obtained over a conveniently small temperature range, the activation energy for diffusion of the predominant impurity—nitrogen—can be found. This energy agrees favorably with earlier determinations made over a much wider temperature range using iron wire with specially introduced impurities.
Elementary Study of Impulsive Forces
Authors: Jeffers Fred , Soules Jack A.
Published: August 2005

A useful teaching experiment on impulsive forces is described in which ball bearings are dropped onto a block of hard rubber. A simple analysis shows that a sizable velocity-dependent force comes into play when the ball strikes the rubber. The data obtained in this experiment are reproducible within ±3% and the analysis is easily understood by the beginning physics student. The experiment dramatically illustrates that impulsive forces are large and that they may be quite complicated.
Energy Conservation as the Basis of Relativistic Mechanics
Authors: Penrose R. , Rindler W.
Published: August 2005

The relativistic theory of collisions of macroscopic particles is developed from the two axioms of energy conservation and relativity, by use of standard relativistic kinematics (without, of course, assuming the mathematical expression for relativistic energy). We derive, in turn, the equivalence of rest-mass and rest-energy, the usual mathematical expression for the total energy in terms of the rest-energy, the conservation of 3-momentum, and the equivalence of total energy with inertial mass. We incidentally find all possible conservation laws of quantities described by the product of a scalar with a function of the speed.
Radioactivity before the Curies
Authors: Badash Lawrence
Published: August 2005

A scientific discovery of great significance need not lead inexorably to widespread and more penetrating investigation. Immediately after Becquerel's discovery of radioactivity and his study of some physical properties connected to the phenomenon there was very little interest evident among his colleagues. In fact, radioactivity lay essentially moribund until the Curies began their investigations using a new and fertile approach. The story of the two years between Becquerel's discovery and Marie Curie's first research is illustrative of the manner in which a major physical phenomenon may remain neglected, even after it was first observed, because of the confusion of related studies and a failure to recognize its relevant properties.
A Simplified Construction of a Helium-Neon Visible Laser
Authors: Vander Sluis K. L. , Werner G. K. , Griffin P. M. , Morgan H. W. , Rudolph O. B. , Staats P. A.
Published: August 2005

Detailed instructions are given for the construction of a simple inexpensive dc powered helium-neon laser with 6328-Å output. The design is for a 60-cm confocal resonator with a few milliwatts of coherent power output and rich mode structure. Variations to the basic design are suggested. Basic demonstrations that can be performed with the laser are described.
Resource Letter AT-1 on Achievement Testing
Authors: Kruglak Haym
Published: August 2005

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

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

Notation: The letter E after an item number indicates elementary reading level, the letter I indicates intermediate level, and the letter A indicates advanced material principally suited for senior, graduate study. An asterisk (*) indicates items particularly recommended for introductory study.

Additional copies: Available from American Institute of Physics, 335 East 45 Street, New York, New York 10017. When ordering, request Resource Letter AT-1 and enclose a stamped return envelope.
Maxwell's Distribution Law from Stochastic Considerations
Authors: Chaturvedi B. K. , Mitra Ved
Published: August 2005

An assembly of molecules of a monoatomic gas, treated as hard elastic spheres, is formed such that the disorder or entropy is maximum, by applying a force on each individual molecule (supposed to have zero initial velocity) for very short intervals—which ultimately tends to zero—and changing its direction of application randomly. The assembly is in equilibrium as the entropy is maximum and the distribution function comes out to be the Maxwellian distribution.
“Spherical” Coordinates in Special Relativity
Authors: Mast Cecil B.
Published: August 2005

In the limit at which geometric optics is valid, a light signal may be represented (in special relativity) by a (straight) null line. If we consider an event P, then the past null cone drawn from P represents all events visible to any observer at P. The configuration of events perceived by any one observer may be obtained by projecting this cone onto the 3-flat orthogonal to the observer's 4-velocity in a suitable fashion. In this paper a projection technique is described and leads naturally to a system of spherical coordinates for each observer. The transformation of coordinates for two observers is obtained and some applications are discussed.
Intermediate Physics Laboratory at Clemson
Authors: Miller M. G. , Skove M. J.
Published: August 2005

A course which emphasizes techniques rather than appreciation is discussed. The use of conferences and research notebooks rather than weekly reports, and the practice of having the student plan his own experiments leads the student toward being capable of doing independent work.
Energy Levels in a Yukawa Potential
Authors: Rawls John M. , Schulz Michael
Published: August 2005

A calculation of selected energy levels in a Yukawa potential utilizing the Bohr theory yields results which are in good agreement with those given by more difficult methods. A new result obtained is an expression for the number of bound states.
Rolling Precession
Authors: Guest P. G.
Published: August 2005

The path described by a rolling truncated sphere is shown to be an equiangular spiral. An undergraduate laboratory experiment is described in which this motion is studied.
Low-Frequency Circuit for Driving a Galvanometer in Forced Linear Oscillation
Authors: White Locke
Published: August 2005

For experiments in forced linear oscillation, a square wave is integrated to a triangular wave, and that is shaped by a pair of diodes to approximate a sine wave. The response of a galvanometer driven by the shaped wave matches quite closely the response calculated for a pure sinusoidal forcing function over the frequency range of interest here, from 0.5 to 2 times the resonant frequency. One advantage of the circuit is that the student observes the phase lag quite directly.
Computers and Physics Teaching. Part I: Digital Computers
Authors: Shirer Donald L.
Published: August 2005

Modern electronic computing machines have drastically changed the problem-solving techniques of the physicist. This change ought to be reflected in the undergraduate curriculum by the introduction of the elementary applications of analog and digital computers. These machines may also be used to advantage in lecture demonstrations, laboratories, independent research projects, and homework assignments. This article comments at length on the ease with which digital computers may be employed in many phases of physics teaching through the use of machine translation for programs written in algebraic languages such as fortran or algol. Sample programs are discussed.