bluuebunny/crossref_metadata_2025 huggingface dataset:
Experiment in Cryogenics for the Undergraduate
Authors: Stillwell E. P. , Gardner R. L. , Littlejohn H. T.
Published: August 2005

A simple piece of inexpensive apparatus is described with which experiments may be done between 2° and 300°K directly in a liquid-helium storage Dewar. The apparatus is suitable for use by undergraduates, and an experiment to determine the temperature dependence of resistance and the superconducting transition temperature of tin is described.
Demonstration of the Doppler Effect for Acoustic Waves
Authors: Rovers W. , Skarsgard H. M.
Published: August 2005

A system providing a quantitative electronic determination of the Doppler effect of acoustic waves is described. The system makes use of a movable detector tuned to a frequency slightly different from that of a signal delivered to a fixed loudspeaker. A resonance condition is exhibited when the Doppler-shifted frequency “seen” by the moving detector corresponds to the frequency at which it is tuned.
The Richtmyer Memorial Lecture—Gravitation and Cosmic Physics
Authors: Dicke R. H.
Published: August 2005

Most fundamental questions about gravitation cannot be answered with puny experiments performed in the laboratory. Fortunately, nature provides ready-made experiments on gravitation, and these are performed on a grand scale. Examples are given, and their significance for general relativity is discussed.
Entropy and Temperature in Equilibrium Statistical Mechanics
Authors: Weinstock Robert
Published: August 2005

The problem of relating the statistical mechanics of a weakly interacting system to its macroscopic thermodynamic description is confronted. Following a brief discussion of previous solutions, a treatment exhibiting some novel features is presented—first for a pure system, then with generalization to mixed systems in which combination and dissociation may or may not occur. In each case the second law, along with a small number of explicitly stated additional assumptions, is employed in the derivation of formulas for absolute temperature and entropy in terms of quantities indigenous to the statistical mechanics of the system.
Spin-1/2 Particles in a Gravitational Field
Authors: Coulter C. Alton
Published: August 2005

A recently proposed approach to the formulation of gravitational theory, in which all a priori mention of curvlinear coordinate systems and space-time can be avoided, is illustrated by applying the method to the particular case of the Dirac field. The basic procedure used is that of starting with an invariance property of the special-relativistic free Lagrangian under some class of transformations, identifying the associated conserved “current,” and then finding a field which interacts with this conserved current by requiring that the Lagrangian be altered so it remains invariant even when the original transformations become coordinate-dependent in an appropriate fashion. For purposes of illustration, the technique is first used to derive the electromagnetic interaction of the Dirac field, and then the gravitational interaction of this field is worked out. A comparison of the resulting theory with general relativity is given. The emphasis throughout the paper is on concepts rather than on a detailed mathematical development.
Study of Spectral Representations for Simple Quantum-Mechanical Systems
Authors: Hellman W. S. , Roman P.
Published: August 2005

Spectral representations for two-point functions of point quantum-mechanical systems are derived, under very general assumptions. Sum rules are then obtained, both for systems with velocity independent and dependent interactions. The implications of these sum rules are illuminated on particularized simple systems. Special attention is paid to systems where a zero-frequency (translational) mode exists. The difference between velocity-dependent and -independent interactions is shown to be very crucial in this respect. The same analysis provides an instructive example of inadvertent misuse of the spectral representations. Finally, the possibility of Goldstone behavior, with all its consequences and implications, is demonstrated for systems with finite many degrees of freedom.
Charged-Particle Detector Experiments for the Modern Physics Laboratory
Authors: Duggan Jerome L. , Adams William D. , Scroggs Robert J. , Anthony Lee S.
Published: August 2005

The relatively new type of charged particle detector known as the semiconductor detector has revolutionized the counting procedures in the field of low-energy nuclear physics. Its good resolution properties, coupled with its ease of operation, make it a natural to use in an undergraduate physics laboratory. In this paper several rather basic experiments are outlined with the use of these detectors. An alpha experiment is presented which gives the basic concepts of resolution and calibration with charged particle detection systems. Next, an alpha-decay scheme is analyzed with the corresponding gamma spectrum from the source. A (dE/dx) experiment is presented illustrating alpha particle energy loss in thin metallic foils and air. Finally an alpha-x-ray coincidence experiment is performed in both the usual coincidence manner and with a time-to-pulse-height converter. With the latter method the time distribution of the coincidence pulses is also measured.
The New Mexico State University Stern-Gerlach Apparatus
Authors: Daybell Melvin D.
Published: August 2005

A simple version of the Stern-Gerlach experiment on space quantization of atomic angular momentum, utilizing a potassium atomic beam and a movable “hot-wire” detector, has been developed. A vacuum system of Corning glass pipe simplifies construction and displays the operation of the device. A general description of the apparatus is given, as is performance data and information on its use in undergraduate laboratories. A detailed construction and use manual, including shop drawings, is available from the University.
On the Interpretation of the Energy Spectrum
Authors: Chiu Wan-Cheng
Published: August 2005

Under different methods of representation, a spectral curve takes on different shapes. It is possible that the peak of a spectrum is found at different periods in different representations. The significance of the spectral peak is discussed.
Electronic Transport in Graded-Band-Gap Semiconductors
Authors: Van Ruyven L. J. , Williams F. E.
Published: August 2005

After briefly reviewing the theory of abrupt semiconductor heterojunctions, we consider a semiconductor whose composition gradually changes from that of a small-band-gap material at one end to that of a large-band-gap material at the other. From general theoretical aspects of the energy-level structure of nonuniform semiconductors, we clarify the sense in which the system has a graded band gap. In order to separate the effect of the graded band gap on electronic charge transport from the effect of the electric field originating from space charges, we consider a graded-band-gap semiconductor which is doped inhomogeneously with donors and acceptors so that there is no space charge. Electronic transport is analyzed by a novel method which is based on intraband transitions between eigenstates of the complete Hamiltonian. In addition to the normal diffusion term, another term is obtained which is linear in the gradient of the band edge for each type of carrier. In previous work this term was ascribed to a “quasifield”; we show that it originates from asymmetric diffusion. The transport equations for both types of carriers are presented.
New Approach to Statistical Mechanics
Authors: Weinstock Robert
Published: August 2005

An elementary mathematical method is introduced for evaluating the average energy-state occupation numbers of a system of noninteracting particles in thermal equilibrium. Conceptualization of the problem is identical with that of Darwin and Fowler; but the execution avoids, without sacrifice of rigor or generality, the use of their profound analytic-function-theoretic machinery. The case of Maxwell-Boltzmann statistics is initially handled separately, but a more general unified treatment is also provided for Fermi-Dirac, Bose-Einstein, and Maxwell-Boltzmann systems as special cases. The three familiar distribution functions, with a known general formula for their mean-square fluctuations, are derived. The methods are also applied to mixtures of systems, with and without the possibility of combination and dissociation.
Mass of the Neutron: A Student Exercise
Authors: Banta H. E. , Noakes John E.
Published: August 2005

A standard way to measure the mass of the neutron is to measure the energy of the capture-gamma ray from hydrogen. Careful measurement with a lithium-drifted Ge detector offers reasonable accuracy in determination of this energy. The measurement has been made using student-type equipment, and resulting in a mass of 1.0086654 ± 0.0000008 amu. It is proposed that this is a suitable experiment for an advanced physics laboratory.
Microwave Research and Demonstration System
Authors: Reid William M.
Published: August 2005

A low-cost experimental and demonstration microwave system operating in the x band is described. Some of the features of operational radars are preserved for use in a laboratory situation. Other aspects of service radars (such as the scanning antenna) are lost. The resulting system is a blending of the good features of operational superheterodyne radars with the low-power laboratory x-band signal generator. Many uses for the system are suggested including antenna-pattern studies, radar cross section measurements, demonstrations of standing waves, measurement of wavelength, etc.
Rutherford Scattering with a Low-Energy Cockcroft-Walton Accelerator
Authors: Duggan Jerome L. , Yegge John F. , Ford Kay
Published: August 2005

Rutherford scattering experiments are traditionally performed in the college physics laboratory with an alpha source and some suitable scattering foil. Simple calculations based on reasonable source strengths, geometry, and cross section show that it is very difficult to measure the complete Rutherford angular distribution by this method. The reason for this difficulty is, of course, that the cross section can decrease by a factor of 105 from the forward to the back angles. The purpose of this paper is to show that the Rutherford angular distribution can be measured in a reasonable laboratory period with a low-energy Cockcroft-Walton accelerator. Many universities have these accelerators or plan to add them to their lists of capital equipment. To date, these machines are used almost exclusively as neutron generators with the T(d,n)4He or D(d,n)3He reactions. These accelerators can easily be modified to include charged-particle experiments. In this report, the general format is given for measuring the Rutherford angular distributions for 150-keV protons for the following reactions: C12(p,p)12C, Ni58(p,p)58Ni, , B11(p,p)11B, and Au197(p,p)197Au. At Oak Ridge Associated Universities, we have performed charged-particle experiments similar to those outlined with many undergraduate physics students, as well as their professors. The results have been most gratifying.
Laboratory Built on Air
Authors: Fox John N.
Published: August 2005

A modified open-ended laboratory in mechanics at the general-physics level is described for use in a small liberal arts college. The purpose, equipment required, and laboratory procedure are discussed.
Project Laboratory in Electricity and Magnetism
Authors: Shonle John I.
Published: August 2005

An unstructured laboratory of the project type is described. Although the specifics apply to a junior-level laboratory in electricity and magnetism, many of the general features may be applied to other sorts of laboratory courses. The relative advantages and disadvantages are evaluated after three years experience.
Systematic Approach to the Teaching of Lens Theory
Authors: Walther Adriaan
Published: August 2005

A general description of optical instruments is presented, which can be used to treat geometrical optics, Fourier optics, and the wave theory in a unified manner. It is shown that a joint treatment of these various branches of optics clarifies many results that quite often remain intuitively obscure to the student; e.g., the Legendre transformations in eikonal theory attain an immediate significance in the context of the wave theory. Students of a course along these lines must have a moderate knowledge of Fourier integrals. In the final section it is shown that diffraction theory can be described in terms of a “sum over all rays” concept.
Maxwell and the Electromagnetic Wave Equation
Authors: Bork Alfred M.
Published: August 2005

Maxwell's three derivations of the wave equations in electromagnetic theory are discussed and displayed on three charts.
The Birth of “Plasma”
Authors: Tonks Lewi
Published: August 2005

The origin of the “plasma” of gaseous electronics need not be mythological. The author was there.
Vector Lorentz Transformations
Authors: Cushing James T.
Published: August 2005

A derivation of the vector Lorentz transformation is given by explicitly compounding the pure Lorentz transformation along one spatial axis with pure spatial rotations. The orthogonal matrix is found which expresses the spatial rotation produced by two successive vector Lorentz transformations and is applied to the Thomas precession of an accelerated frame relative to an inertial one. The method used is basically that outlined in Møller's book.
Fresnel's Convection Coefficient in a Dispersive Medium
Authors: Price Harold Edwin
Published: August 2005

The version of Fresnel's formula for the convection coefficient is given in different forms (for dispersive media) in different textbooks. The differences are often confusing. The reasons for this situation are analyzed, and the interconnections between the various formulas are shown.
Catching a Baseball
Authors: Chapman Seville
Published: August 2005

A baseball fielder will arrive at the right place at the right time to catch a fly ball if he runs at the only constant velocity for which the rate of change of tangent of the elevation angle of the ball and the bearing angle of the ball both remain constant. Remarks are made concerning curve balls. Baseball is not a scientific game—although, unknown to the players, many principles of physics can be applied to it.
Laboratory Arrangment in a New Perspective
Authors: McCord William M.
Published: August 2005

Laboratory experience and the theoretical aspects of physics must merge for a complete and thorough introductory physics program. A new approach to the laboratory experience has been under study and development during the past five years at Orlando Junior College, a private institution with a physics (1966–1967) enrollment of 105 students from a student body of 2361. Obvious trademarks of this laboratory are a diversity of interests, educational excellence, and economy. Thirty permanent experimental stations, seventy other experiments on open shelving, total blackout booths for optics, a single-concept film booth, a director's office in the laboratory, and an adjoining small class or seminar room show the efficiency of this plan. A description of the organization and attractiveness of the laboratory as well as its unique utilization of wall, ceiling, and floor space is given in this paper.
A Simple Apparatus for Moseley's Law
Authors: Hohenemser C. , Asher I. M.
Published: August 2005

A simple undergraduate experiment on Moseley's law is discussed. Illustrative data are given. The apparatus consisted of a Co57 source, a proportional counter, a preamplifier, and an oscilloscope. Various extensions of the work into semi-independent projects are also suggested.
The Advantage of Teaching Relativity with Four-Vectors
Authors: Brehme Robert W.
Published: August 2005

An argument is given that teaching relativity from the beginning using four-vectors provides a powerful and correct way of thinking that also conforms to everyday methods of making measurements. In particular, it is pointed out that the emphasis on the relativistic mass is both undeserved and misleading.
Lorentz Transformation
Authors: Harvey A. L.
Published: August 2005

A simple-straightforward derivation of the most general form of the homogeneous Lorentz transformation is presented. In the process, the well-known decomposition of a generic element of the group into two pure rotations and a “one-dimensional” Lorentz transformation is obtained in a physically obvious manner.
On Snell's Law and the Gravitational Deflection of Light
Authors: Tangherlini Frank R.
Published: August 2005

It is shown that by allowing for an effective mass increase in the corpuscular theory of light, the particle travels slower rather than faster on entering an optically denser medium. The viewpoint and results are consistent with the photon description. The method leads to an improved treatment of the Newtonian deflection of light in a gravitational field, and the relation of this deflection to the general relativistic deflection is considerably clarified. It is pointed out that the gravitational index of refraction and the electromagnetic index of refraction are not equivalent as regards the motion of charged particles.
The “Instrumented” Laboratory
Authors: Soules J. A. , Bennett R. B.
Published: August 2005

This is a preliminary report of the author's project at the CCP Summer Workshop on Introductory Laboratory to produce descriptions of some simple transducers and circuits for their operation. The availability of such transducers in laboratory would allow many experiments to be extended in directions of student choice and make his laboratory experience more closely approximate to that of a physicist.
On the Trouton-Noble Experiment
Authors: Butler J. W.
Published: August 2005

The experiment of F. T. Trouton and H. R. Noble to detect the motion of the earth through the ether by means of electromagnetic torque on a charged, suspended, parallel-plate capacitor is reexamined. No previous explanation of the null result appears to be satisfactory because, as is shown herein, conventional relativistic electrodynamics predicts that the total electromagnetic field energy of the capacitor is different in the two orientations. Therefore, this combination predicts that the result should not be null. A new explanation of the null result is offered, based on a new equation for the energy density dU/dV in the electric E and magnetic H fields of a classical macroscopic charged body with a uniform speed β in units of the speed of light. This new equation dU/dV = (E2−H2)/8π(1−β2), in Gaussian units in vacuo, predicts that the total electromagnetic field energy of the capacitor is independent of its orientation in agreement with the null result of Trouton and Noble.
An Inexpensive Vacuum-Tube Electrometer
Authors: Edmonds Dean S.
Published: August 2005

This paper describes a simple, yet accurate, vacuum-tube electrometer that has proved very useful in the teaching laboratory for measuring the small currents involved in various modern physics experiments. Details of the circuit design and construction are given. In addition, an electrometer test setup is described and the results obtained with the electrometer here considered are presented. The results indicate that this unit has an over-all precision of better than 4% on its 10−10 A full-scale range and a response time (including the recorder) of less than 12 sec for full-scale travel following application of a step function input. A simple modification allowing measurement of resistances up to 1011 Ω is also indicated.
Demonstrations of Fluid Flow in a Rotating System II: The “Spin-Up” Problem
Authors: Baker D. J.
Published: August 2005

Lecture demonstrations and/or possible undergraduate laboratory experiments which underline the importance of the time-dependent motions in rotating fluids for geophysical and astrophysical problems are presented here. The secondary flows which occur when the container of a fluid in rigid-body rotation changes velocity, which lead to such well-known effects as the teacup flow and river meanders, and which have a profound influence on large scale natural fluid flow, are considered following the theoretical treatment of Greenspan and Howard. The demonstrations of this “spin-up” problem illustrate (a) the difference in spin-up times due to boundaries parallel and perpendicular to the rotation axis, (b) frictional boundary layer formation and induced secondary horizontal flow, and (c) the vertical velocities induced by flat bottom boundary velocity changes.
Elementary Nuclear Physics with a Van de Graaff Accelerator
Authors: Treado Paul A. , Lambert James M.
Published: August 2005

Experiments utilizing a low-energy accelerator and ancillary equipment are described. The experiments are suitable for use in physics laboratory courses.
A Quantum-Mechanical Ripple Tank
Authors: Daniels Walter E. , Schwartz Judah L.
Published: August 2005

The partial wave expansion for a quantum-mechanical plane-wave scattering from a hard sphere is evaluated numerically, and various graphical presentations of the probability density are made.
The Bethe-Weizsäcker Mass Formula and Lennard-Jones N-N Potentials
Authors: Wesley James Paul , Green Alex E. S.
Published: August 2005

An elementary derivation of the Bethe-Weizsäcker semiempirical nuclear mass formula which is in the spirit of current views of nuclear structure, is given. Lennard-Jones potentials are assumed to act between nucleons. Thus the major interaction between nn, pp, and np pairs is taken of the form −gsol;r3+hsol;r4, where r is the separation distance between nucleons, and g and h are constants. An additional “symmetry” interaction of the form −s/r3 is assumed for np pairs. Summing the potential energy over all nucleon pairs and using the Fermi statistical estimate of the kinetic energy, the Bethe-Weizsäcker semiempirical mass formula is obtained directly. The constants of the mass formula are discussed in relation to the N-N interaction and are found to be quite plausible.
Henri Poincaré's Mathematical Contributions to Relativity and the Poincaré Stresses
Authors: Cuvaj Camillo
Published: August 2005

Henri Poincaré was the first to introduce four-vectors, the Lorentz group and its invariants (including the space-time metric), “Poincaré stresses,” as well as making other valuable contributions to relativity theory. We owe to him the names: “Principle of Relativity,” “Lorentz group,” “Lorentz transformation,” and “invariants of the Lorentz group.” It will be shown that his main contributions to relativity were those of a mathematical nature. This has not been sufficiently recognized, although his physical contributions to relativity have been much discussed recently. Frequent misunderstanding of the work of Poincaré and Einstein has resulted in controversy tending to obscure the main achievements of Poincaré. The Poincaré stresses are discussed because of widespread ignorance regarding the theory of classical fundamental charges. The emphasis in this article is on those accomplishments of Poincaré by which he should be better known today. In addition, some misconceptions about the history of relativity and classical electron theory will be corrected.
The One-Dimensional KDP Model in Statistical Mechanics
Authors: Nagle John F.
Published: August 2005

It is observed that the one-dimensional analog of the Slater KDP model provides a simple introduction to the study of strongly interacting systems and phase transitions as well as to recent research on two-dimensional KDP models. Although the first-order phase transition of the one-dimensional Slater model technically disappears when more realistic interaction strengths are taken into account, an anomalously large specific heat remains in the modified one-dimensional model.
A Diagrammatic Mnemonic for Calculation of Cascading Level Populations
Authors: Curtis L. J.
Published: August 2005

A diagrammatic procedure is described, by which the time dependence of the population of any level in a decay scheme of arbitrary complexity can be prescribed directly in terms of transition probabilities and initial populations, without specifically solving the determining differential equations.
A New Approach to Teaching of Elementary Physics
Authors: Bertman B. , Chase Walter , Creeger E. S. , Fox J. N. , Krogh Christine
Published: August 2005

A radical departure from the traditional method of teaching elementary physics has been tried and is described. The new approach is based on individual work, especially in the laboratory. Preliminary results are discussed.
Algebraic Equivalence of the Lagrangian and of the Hamiltonian Forms of the Equations of Motion
Authors: Levitas Alfred D.
Published: August 2005

The problem of deriving the Hamiltonian form of the classical equations of motion from the Lagrangian form, and vice versa, is treated algebraically utilizing the explicit dependence of the kinetic energy on the generalized velocities. A method of constructing the Hamiltonian function and the canonical equations of motion from the dependence of the kinetic energy on the generalized velocities is given. The relationship between the Hamiltonian of a system and the energy of a system is obtained without the use of Euler's theorem, and is given for the general case, that is for the case in which the equations transforming from the Cartesian coordinates to the generalized coordinates explicitly involve the time. Some identities involving second partials of the Hamiltonian function and the Lagrangian function are obtained.
Fermi's Theory of Beta Decay
Authors: Wilson Fred L.
Published: August 2005

A complete English translation is given of the classic Enrico Fermi paper on beta decay published in Zeitschrift für Physik in 1934.
Raman Spectroscopy Experiment for the Senior Laboratory
Authors: Fugitt B. R. , Rupaal A. S.
Published: August 2005

A description is given of the design, construction, and performance of a Raman source which could be used in a senior laboratory accompanying optics and spectroscopy courses. The apparatus utilizes a single low-pressure mercury arc lamp at one focus of an elliptical housing. Light scattered axially from the Raman sample at the other focus is condensed onto the spectrograph slit via a lens system which also eliminates non-scattered radiation. When used with a Hilger and Watts model D-186 constant deviation spectrograph, a spectrum for CCl4 was obtained after an exposure of about two minutes on general purpose spectrographic plates. The classical spring constant is calculated for CS2.
Single Electrometer Method of Measuring Transport Properties of High-Resistivity Semiconductors
Authors: Baleshta T. M. , Keys J. D.
Published: August 2005

A method is described whereby the electrical conductivity and Hall coefficient of high-resistivity semiconductors can be measured using a single electrometer for current and voltage measurements. Measurements are made following the L. J. van der Pauw technique with the electrometer switched to perform the necessary functions while maintaining the low side at ground potential. The variation of conductivity and Hall coefficient with temperature can be determined by a point by point method or the data can be recorded on an X-Y recorder. Conductivities as low as 10−10Ω−1·cm−1 have been measured.
Hyperfine Structure in Bismuth—An Experiment
Authors: George S.
Published: August 2005

The arc spectrum of bismuth has been photographed using the 3.4 m Ebert plane grating spectrograph. The light source used is a commercially available sealed-off hollow cathode discharge. The hyperfine structure of the lines λ = 3596 Å in the seventh order and λ = 4122 Å in the sixth order have been studied. It is pointed out that without using special spectroscopic light sources and high resolution interferometers, the hyperfine structure can be studied in detail with reference to their separations and relative intensities. From the results, this experiment is recommended as suitable for an advanced optics and spectroscopy or quantum physics laboratory.
Temperature Variation of Nuclear Quadrupole Resonance Frequencies
Authors: Baker G. L. , Armstrong R. L.
Published: August 2005

A superregenerative nuclear quadrupole resonance spectrometer designed for use in an advanced undergraduate laboratory is described. The temperature variations of the Cu63 and Cu65 resonances in Cu2O are investigated. The results yield information on the lattice dynamics of Cu2O and allow a determination of the ratio of the nuclear quadrupole moments of the copper isotopes.
Thermodynamic and Statistical Aspects of Magnetic Cooling
Authors: Weinstock Harold
Published: August 2005

A unified account is given of the thermodynamic and statistical aspects of magnetic cooling with particular reference to adiabatic demagnetization of a paramagnetic salt. Nuclear cooling and the adiabatic magnetization of antiferromagnets and superconductors are also considered along with the related phenomena of negative temperatures and para-electric cooling.
Energy Transfer in One-Dimensional Collisions of Many Objects
Authors: Hart John B. , Herrmann Robert B.
Published: August 2005

The conservation of linear momentum and the coefficient of restitution are used to derive a formula in which the fraction of energy transferred through n bodies in one-dimensional collisions depends upon the coefficient of restitution, the relative masses of the bodies, and the number of bodies involved. The percent of energy transferred is graphed as a function of the coefficient of restitution and the number of particles which constitute a mechanical impedance-matching-taper transformer between two end particles whose mass ratio is one-hundred. A demonstration device illustrating the impedance match is discussed.
Mechanical Demonstration of Excited States
Authors: Fox J. N. , Arlotto J. J.
Published: August 2005

This paper describes an experiment using a linear air track, which demonstrates the conservation of energy during a collision between an “electron” and an “atom” capable of being raised to an excited state during the collision. The experiment proves that the minimum energy of the incident “electron” required for excitation is larger than the actual excitation energy.
Agreement Between Classical and Quantum Mechanical Solutions for a Linear Potential Inside a One-Dimensional Infinite Potential Well
Authors: Dymski Terrance C.
Published: August 2005

For the special case in which the total energy is set equal to the classic maximum potential energy, the Schrödinger equation is solved in closed form and is normalized. It is shown that the expectation value of position is equal to the classical time average of position and that the expectation value of the square of the momentum is equal to the classical time average of the square of the momentum.
Demonstration Experiment of Heat Flow in Transient and Steady-State Conditions
Authors: Morris D. A.
Published: August 2005

The theory and technique of producing an electrical analog of one-dimensional heat flow in a bar is discussed in detail. The motivation of the work was to find a way of providing visual displays of solutions to heat-diffusion equations.
Type II Superconductivity Experiment
Authors: Merrill John R.
Published: August 2005

This paper discusses an advanced laboratory experiment concerning the resistive and magnetic properties of the type II superconductor Pb85In15. The magnetic behavior is determined from magnetization studies on a PbIn sphere. The resistive behavior is determined by means of a PbIn wire with a magnetic field both parallel and perpendicular to the axis. The critical fields for the alloy are studied as functions of current and temperature. The student learns not only the phenomenology of type II superconductivity, but also how to use liquid helium and its associated hardware. The results presented are typical of students' results in the laboratory.
Bloch-Type Equations for Acoustic Nuclear-Magnetic Resonance
Authors: Scotus Breitbart Mary Duns , Barker W. A.
Published: August 2005

Acoustic nuclear-magnetic resonance differs from the conventional NMR in that an acoustic signal of frequency ω at or near the nuclear Larmor frequency ωo = (gnβnHo)ħ−1 or its first harmonic is applied to the sample instead of the customary electromagnetic signal. In the acoustic case nuclear Zeeman transitions are induced by virtue of a modulated nuclear-electric quadrupole interaction in contrast with the conventional situation where the nuclear-magnetic dipole interaction is operative. In spite of these differences, it is possible to write phenomenological equations of the Bloch form, familiar in the theory of conventional NMR, for the case of acoustic NMR, providing an appropriate choice is made for the amplitude and direction of the effective magnetic field. This macroscopic description of acoustic NMR is applicable for negligible saturation.
Ideal Rare-Gas Crystals
Authors: Horton G. K.
Published: August 2005

In this review-tutorial article, the principal theoretical and experimentals results concerning the lattice properties of ideal inert-gas crystals are presented and discussed. The work published since Pollack's article is emphasized. It is shown that there are no qualitative disagreements between theory and experiment. Where theory and experiment are reliable, quantitative agreement is found between the measurements and the predictions based on simple two-body central potentials.
Nature of Quantum States
Authors: Park James L.
Published: August 2005

This paper carefully explores the relations among the statistical ensembles, systems, and states (pure and mixed) of quantum theory. By systematically contrasting the classical and quantal realizations of a general paradigm for a probabilistic physics, important distinctions are exposed both in statics and dynamics. Included are observations concerning the intrinsic ambiguity of the quantum-state concept and the peculiarly quantum property of dynamic indivisibility. It is concluded that the conceptual gulf between classical states and quantum “states” is wider than commonly assumed.
Coordinate Transformations of W. Voigt and the Principle of Special Relativity
Authors: Gluckman Albert G.
Published: August 2005

The relationship existing between the Voigt transformation and the Lorentz transformation is discussed. Some properties of the Voigt transformation are considered, especially its conformal nature. The mechanical meaning of the Voigt transformation is treated, i.e., the moving oblate spheroid, and a moving clock. The addition of velocities theorem developed by application of the special Voigt transformation and the addition of velocities theorem developed by application of the Lorentz transformation are shown to be identical. Finally, the mechanical necessity that the special Voigt coordinate transformations be altered in order to construct the Lorentz electron model, and the electrodynamic consequences of the Voigt kinematics are discussed.
Fields Due to a Slow Charged Particle Moving Parallel to a Plane-Metal Surface
Authors: Shier John S.
Published: August 2005

A solution is found for the fields due to a charged particle moving parallel to a plane-metal surface in the limit of low velocity. It is found that the current distribution in the metal is mathematically simple; the current density has a dipole pattern of flow. The solution offers interesting examples of charge conservation and the use of the uniqueness theorem in solving potential problems.
General Relations for C and G Parities of Particle-Antiparticle Systems with Arbitrary Spin and Isospin
Authors: Laverriere R. , Proriol J. , Thevenet C.
Published: August 2005

We derive the eigenvalues of the charge conjugation C and of the G transformation for particle-antiparticle systems of arbitrary spin and isospin. The eigenvalues are given by the formulas C = (−)L + S and G = (−)L + S + T where L is the angular momentum, S the spin, and T the isospin of the particle-antiparticle system.
Demonstration Experiment Using a Dissectable Anharmonic Oscillator
Authors: Fox J. N. , Arlotto J. J.
Published: August 2005

The concept of perturbations is introduced to the general physics student using a forced anharmonic oscillator constructed on a linear air track. The interaction between a bar magnet mounted atop the glider and two U magnets supplies the perturbation. The general characteristics of the system are described, and plots of the amplitude versus driving frequency showing a “jump” effect are presented. The advantage of the system described is that all components of the system are open to study by the student.
High-Pressure Viscosity Experiment for the Undergraduate Laboratory
Authors: Stajdohar Ralph E. , Towle Laird C.
Published: August 2005

A falling-ball type of viscometer has been developed employing remote sensing of the ball position. It has been utilized in measurements of the effect of pressure on the viscosity of liquids in the range up to 2 kbar. The experiment is well suited to use in the undergraduate physics laboratory.
Green's Function Theory of Ferromagnetism
Authors: Patterson J. D. , Southwell William H.
Published: August 2005

The Green function method is applied to a system consisting of two spins which are coupled by exchange. The magnetization, the correlation function, the zero-field magnetic susceptibility, and the magnetic specific heat are evaluated. Since the two-spin system gives Green function results easily, and since exact results are calculated for comparison, the two-spin system is a particularly effective teaching tool for the Green function method. The calculations in this paper assume that the exchange coupling of the spins is as described by the Heisenberg Hamiltonian, and we treat only the case of positive exchange integral J. Only the case of spin 1/2 and Tyablikov decoupling (or the random phase approximation) is considered in this paper. As might be expected the Tyablikov decoupling approximation gives poor results, but this is compensated by the ease with which the Green function results are obtained. However, in many cases one can simply generalize to larger spins and other decoupling approximations, if desired. Generalizations are also possible for larger “clusters” of spins with constant J for each pairwise interaction.
Optimum Design of Student Experiments on Rutherford Scattering
Authors: Burge E. J. , Edwards V. R. W. , Lewis V. E. , Ganguly N. K.
Published: August 2005

The optimum design of student experiments on Rutherford scattering is investigated in terms of both minimum counting times and range of useful experience of scattering techniques. The geometrical corrections for an annular target, source, and detector of finite sizes are presented; and the multiple-scattering and energy-variation corrections for a target of finite thickness are considered in detail. Apparatus is described and results presented for measurements over the range 15°–90°, using an α source of activity about 100 μCi, with the differential cross sections at 12 angles measured to an accuracy of ± 5% in about 6 h of laboratory time.
Geometrical Model of Relativistic xtv Space
Authors: Bergström Arne
Published: August 2005

A model in ordinary Euclidean geometry is presented to illustrate the Lorentz transformation formulas of special relativity. In one version of the model, the space-coordinate x in the direction of motion, the time-coordinate τ = ct, and the velocity coordinate β = v/c are represented in a cylindrical coordinate system rθz with r = τ, θ = arcsin β, and z = x. An alternative version is given by r = x, θ = arcsin β, and z = τ. In both versions an event is represented as a straight generatrix of a one-sheet hyperboloid with axis in the z direction. If the angle θ instead is taken to be a spatial angle in a Euclidean space-time world, where light lines take the role of the event-lines in the above xtv-space, it is shown to follow from the above model and Huygens' principle that it would be possible for moving observers to make Lorentz-invariant observations despite the Euclidean metric.
New Grapes from Old Vineyards: Challenging Problems for Creative Students
Authors: Ganley W. P.
Published: August 2005

Mechanics problems for undergraduates and graduate students tend to be exercises rather than fresh new fields for the student to conquer. These exercises are valuable, but are a far cry from theoretical physics. They focus the student's attention on techniques rather than ideas, and the techniques are merely the same ones they have been given in the lecture and the textbook, and have used over and over again. Here are presented several problems in classical physics that are designed to shake the student out of his torpor and make him think about what he wants to do and can do, rather than what he should do according to the rules. These problems break the rules. Some solutions are partially sketched. The problems are (1) wrong-way dynamics; (2) mechanics in the molasses; (3) the radical charges; (4) the vicious-viscous force; (5) Newton and the Appell function.
Time Dependence of Quantum-State Amplitudes Demonstrated by Free Precession of Spins
Authors: Kukolich Stephen G.
Published: August 2005

The time dependence of quantum-state amplitudes is calculated and experimentally demonstrated for the spin states of the rubidium atom. The mechanism of optical pumping is used to prepare the spin state oriented along the z axis. The magnetic field is then quickly switched from the z to the x direction and the light transmitted through the rubidium vapor is used as a probe to measure the probability that the atoms are in the various quantum states with respect to the z axis. The time dependence of absorbed light is calculated, first for the simplified case of spin 12, then for spin 1, and finally for spin 2, which is the value observed in the experiment.
Use of a Neutron Generator in an Undergraduate Laboratory
Authors: Veit J. J. , Lindsay R. H.
Published: August 2005

A nuclear-physics laboratory course of one-quarter duration involving the extensive use of a high-flux neutron generator is described. The generator's characteristics make it a reliable and relatively inexpensive nuclear-physics tool for instructional purposes. Nine typical experiments from the wide range of student investigations possible are discussed. An introduction to present research efforts with the generator is an integral part of the laboratory experience.
“N Waves” from Bursting Balloons
Authors: Deihl David T. , Carlson F. Roy
Published: August 2005

When a round balloon is burst “perfectly,” the resulting acoustic disturbance should have the shape of the letter N. In the experiments reported here, the N wave is received by a baffled microphone, whose frequency-response characteristic is flat to about 80 kHz. The oscillogram of the microphone output is then photographed. The waveforms obtained show deviations from the idealized N shape, which are attributed to loss of spherical symmetry. Important factors determining the departure from spherical symmetry are the type of balloon and the method of bursting. By paying careful attention to experimental technique and photographing the waveforms from many balloons, it is possible to obtain good approximations of the N shape.
Automated Tutoring and Its Discontents
Authors: Taylor Edwin F.
Published: August 2005

An educational experiment is described in which students explore the topic of 4-vectors in special relativity using textbooks and a computer tutorial. The results of the experiment have exposed for us a few of the technical and educational problems lying in the way of general use of such study aids.
Magnetic Interactions between Charged Particles
Authors: Breitenberger Ernst
Published: August 2005

The Lorentz forces exerted by freely moving charges upon one another are not equal and opposite. Conservation of canonical momentum requires, however, that the generalized forces (with components δL/δxj) be equal and opposite. Elementary arguments show that the magnetic interaction terms in the Lagrangian are identical with Darwin's even in the absence of retardation; they arise from relative motion and can therefore not be peremptorily excluded from every nonrelativistic problem involving charged particles, for instance in plasma physics. The formulation of, and separation of variables in, two-body problems with noncentral forces calls for some care because of the wobble motion of the center of mass. In hydrogenic atoms the effects of the magnetic interaction are extremely small; they are contained in the known relativistic correction to the reduced mass correction to the fine structure.
Time-Translation Invariance for Certain Dissipative Classical Systems
Authors: Denman Harry H.
Published: August 2005

Time-translation invariance of the equation of motion for an arbitrary one-dimensional classical system has been shown to generate a conservation law. For conservative systems, this conserved quantity is shown here to be the usual energy. For the linearly damped harmonic oscillator, the explicit form of this constant is found, as well as for quadratically damped systems. In both cases, as the damping approaches zero, the conserved quantity is shown to approach a function of the usual energy. For both types of dissipation, Lagrangians are given which yield the equations of motion.
Will Physics Become Obsolete?
Authors: Strassenburg A. A.
Published: August 2005

This paper presents some new data on physics enrollments and degrees granted at various levels and at various kinds of institutions. Selected aspects of these statistics are discussed. Trend data for the past five years indicate a declining interest in physics as a career. The author establishes a connection between increasing emphasis on specialized courses for future professional physicists and the alienation of the general citizen from science. A broad reason is suggested for the disenchantment of young students with physics which suggests new responsibilities for science educators.
Surface Charges on Conductors Carrying Steady Currents
Authors: Russell B. R.
Published: August 2005

By a general theorem connecting the steady-state electrical potential function for the region surrounding a system of long, parallel homogeneous conductors carrying steady currents to the solutions for the electrostatic potential in the given geometry, it is shown that the density of the surface charges on the conductors varies linearly with distance along the direction of their common axis.
Counterexample to the Lenz-Schiff Argument
Authors: Rindler W.
Published: August 2005

Schiff has claimed that the full general-relativity bending of light round a mass point can be derived from purely radial “free-fall” thought experiments by appeal to Newtonian mechanics and the equivalence principle. Schiff's process is shown to lead to absurdities when applied to a parallel gravitational field. It is valid for time, but not for space. Only the Newtonian free paths and, of course, the gravitational Doppler shift can be validly reobtained by this method.
From Hertz to Gigahertz: An Undergraduate Physics-Electronics Laboratory Course
Authors: Drumheller John E.
Published: August 2005

This paper outlines the one-quarter laboratory course taught at Montana State University which offers a series of experimental “sessions” designed to give junior year students experience at all “electronic” frequencies, stressing those in the microwave region. Such a course offers the possibility of including experiments related to electromagnetic theory and optics in addition to teaching practical electronics. A review of recent literature and a list of advanced experiments using much of the same equipment as well as a discussion of the acquisition of equipment and instructors manuals is included.