bluuebunny/crossref_metadata_2025 huggingface dataset:
Projects in Electricity for Upperclass Undergraduate Students in Physics
Authors: Williamson Chas.
Published: August 2005

Our lecture courses in Electronics and in Electricity and Magnetism, both for physics majors, are accompanied by laboratory courses in which the students elect one or more projects, planning and performing them with minimum help from the instructor. Both verbal and written reports are called for. Projects are of three kinds; in the first, only intelligent selection and use of printed references is required ; in the second, a study of the construction and use of a laboratory device is undertaken ; in the third, a new design of some device is taken from the literature and reproduced with modifications originated by the students themselves. Lists of typical projects are given in this paper.
Resolving Time of a Binary Counter: A Laboratory Exercise
Authors: McConnell R. A.
Published: August 2005

This nonquantitative electronic circuit exercise is suitable for beginning or advanced students. The minimum operating time of a binary counter is measured in microseconds by means of a twin pulse generator. The operating cycle of the latter is studied in terms of its oscilloscope patterns.
A Dynamic Model of Magnetic Resonance Phenomena
Authors: Verbrugge Frank
Published: August 2005

A dynamic model to illustrate atomic and nuclear magnetic phenomena is described. An airdriven spinning magnetic dipole placed in a magnetic field exhibits a Larmor precession whose dependence on magnetic and gravitational parameters can be demonstrated. An ac magnetic field of variable frequency permits a visual demonstration of magnetic resonance.

Data obtained from the precession experiments can be used for a precise determination of the earth's magnetic field.
Training of High School Physics Teachers and Cooperation between College Physics Departments and High Schools
Authors: Martin Donald C.
Published: August 2005

A report is presented of a study made primarily in the Southern States to determine what the certification requirements for teachers of high school physics are and what some college physics teachers think they should be; to determine what special undergraduate and graduate programs of study for those preparing to teach or already teaching high school physics are provided by colleges; and also to discover to what extent college physics departments are cooperating with high school physics departments, by loaning equipment, giving assistance to science clubs, presenting demonstration lectures at high school assembly programs, and discussing opportunities for a career in physics with high school seniors.
A Geometric Approach to Nonrelativistic Spin Theory
Authors: Payne W. T.
Published: August 2005

The requirements that must be satisfied by a nonrelativistic theory of electron spin are examined, and it is shown, with the aid of elementary spinor theory, that these requirements can be met by a geometric scheme whose main operation is the reflection of spinors in an axis. This yields a kind of picture of electron spin. The analytical formulation of the geometric scheme is developed, and is identical with the Pauli spin theory. The part played by nonstationary spin states in the geometric scheme is discussed.
Some Concepts in Modern Physics
Authors: Stern Alexander W.
Published: August 2005

Some concepts and ideas of contemporary physics are surveyed in order that a pattern of scientific thought broader and more meaningful than that permitted by strictly technical approach may be achieved.
Nuclear Magnetism
Authors: Purcell E. M.
Published: August 2005

A review of modern developments in magnetism with special attention to the magnetic effects in gross matter that have their origins in the magnetic moments of nuclei.
The Uncompensated Pendulum Clock
Authors: Dodd Laurence E.
Published: August 2005

From the teaching standpoint in general physics, the pendulum clock uncompensated for temperature change continues to offer valuable material. The present discussion emphasizes that although the oscillation rate is affected by thermal expansion or contraction, causing the clock to “lose” or “gain,” the behavior of the clock remains perfectly normal, that is, “correct,” controlled by physical laws. Consequently, the terms “correct” and “incorrect” should not be applied to period or temperature, but such terms as “standard” or “nonstandard” substituted for them. Attention is focused on the sharp distinction between indicated and actual elapsed time, with indicated seconds per vibration, a constant of the clock, as the key to a clear and general analysis. This constant equals the period only at the standard temperature.
Normal Coordinates
Authors: Secrest E. L.
Published: August 2005

A technique for presenting the concept of normal coordinates to the beginning student of mathematical physics is described. The method differs but slightly from that found in standard textbooks on mathematical physics. This slight difference has been found to be of great assistance to students who are encountering normal coordinates for the first time.
The Recording of X-Ray Diffraction Patterns on Spheres
Authors: Herzog Arno , McLachlan Dan
Published: August 2005

In the teaching of the physics connected with the diffraction of x-rays, as well as the daily research practice of taking x-ray diffraction pictures, it is customary to take the pictures on flat x-ray film or upon sheets of film which has been curved into cylinders. In physics teaching this practice has very definite handicaps and appears to be somewhat indirect, because the theoretical treatment of the diffraction of x-rays is more directly connected to the geometry of spheres. We have, therefore, as a teaching aid, coated the inside surface of some hollow glass spheres with photographic emulsion and have recorded upon these spheres the diffraction of x-rays from small crystals located at their centers. Some of the results are shown in Figs. 1 a, b, and c.
Physics of the Glassy State. I. Constitution and Structure
Authors: Condon E. U.
Published: August 2005

Modern views of the constitution and structure of inorganic glasses are outlined. Materials used in glass making are classified according to their role as network formers and network modifiers. Evidence of structure from x-ray scattering is reviewed. Examples of linear and nonlinear dependence of specific volume on composition are presented, and the classical factors for composition dependence of heat capacity are related to quantum theory of specific heat.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 58. Retombera-t-il?
Authors: Watson E. C.
Published: August 2005

The experiment of firing a cannon ball vertically upward to see whether it would fall back into the mouth of the cannon was carried out in 1634 by Mersenne and Petit. A vignette from Varignon's Nouvelles conjectures sur la pesanteur, which portrays this experiment, is here reproduced.
Wave and Inertial Properties of Matter
Authors: Schlegel Richard
Published: August 2005

The inertial properties of matter as expressed in Newton's second law, and the mass-energy equivalence, are derived as consequences of the deBroglie equation, the Lorentz transformations, and the energy-frequency relation, E = hv. Inertia is then presented as an effect resulting from the frequency and hence energy changes with motion that result from the special relativistic time transformation and apply to mass because of the energy-mass equivalence. The deBroglie wave equation and Newton's second law are shown to be equivalent with respect to a postulate set for the deductive presentation of wave and inertial properties of matter; the deBroglie equation and Newton's second law may therefore be regarded as having the same physical content.
Quantum Mechanics and Thermodynamic Continuity. II
Authors: Landé Alfred
Published: August 2005

The program of deducing quantum mechanics from the postulate of thermodynamic continuity is extended to embrace the principles of symmetry and quantum statistics, in particular the rule of conservation of symmetry type when a system of N particles in resonance interaction is augmented by one more particle. The special quantitative definition of quantum conjugacy contained in the commutation rule of Born and in the Schrödinger replacement of the momentum p by a differential operator may be replaced by a general qualitative physical definition: “p and q are conjugate observables in a mechanical system when the manifold of q reactions of the system uniquely determines the manifold of its p reactions.” When interpreted in terms of superposition mechanics this definition leads to the rules of Born and Schrödinger and from there to quantum dynamics.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 59. Title Page from Alhazen's Opticae Thesaurus
Authors: Watson E. C.
Published: August 2005

Mediaeval optics was dominated by the Kitäb-al-manäzur of Ibn al-Haitham. The Latin translation published at Basel in 1572 and known from its Latin title as the Opticae Thesaurus of Alhazen has an interesting woodcut on its title page which is here reproduced.
Space Charge between Parallel Planes
Authors: Copeland Paul L. , Sachs Lester M.
Published: August 2005

The problem of the potential distribution between two parallel planes at the same potential as a function of the current density passing between the planes is analyzed by successive approximation resulting in power series. The method involves a consideration of the influence of space charge on transit time, and the leading terms of the Maclaurin's series expression for the transit time in powers of the current density are evaluated.
Nuclear Quadrupole Resonance
Authors: Dehmelt H. G.
Published: August 2005

Nuclear quadrupole resonance is a recently developed branch of radio-frequency spectroscopy which is concerned with magnetic resonance absorption in crystals. This absorption is due to reorientation of the nonspherical atomic nuclei against crystalline electric fields. Related phenomena in isolated molecules are briefly mentioned in the Introduction A. This is followed in Sec. B by an elementary treatment of the electrostatic interaction of a nonspherical nucleus with an axially symmetric inhomogeneous electric field as is found approximately in crystalline Cl2, a crystal whose structural units are very nearly undisturbed Cl2 molecules. Electrostatic torques are shown to exist which cause a precession of the nuclear angular momenta around the molecular axes. As this motion is accompanied by a precession of the magnetic and electric moments of the nuclei, which may interact with alternating electromagnetic fields, this leads over to the transition mechanism between the energy levels which are obtained from the corresponding Hamiltonian. Transition and power absorption phenomena are discussed in more detail in Sec. C. In Sec. D effects are treated which either lead to a broadening of the absorption lines or are connected with the thermal agitation in the crystalline lattice. Some experimental aspects are described and examples of observed absorption lines are given in Sec. E. In the concluding Sec. F all nuclei so far investigated with this method are reviewed in three tables. The nuclear information obtainable from such experiments is pointed out.
Hydrodynamic Models of Radioactive Decay
Authors: Knauss Harold P.
Published: August 2005

The flow of water through a capillary from a vessel with vertical walls is shown to simulate the decay of a radioactive sample if the velocity of efflux is low. The rate of flow, when both inertia and viscosity play a part, is worked out under simplifying assumptions.
Critical Reynolds Number and Flow Permeability
Authors: Plain G. J. , Morrison H. L.
Published: August 2005

Liquids of three different viscosities have been used in determining the flow permeability of fourteen media composed of spherical glass beads. Darcy's law has been found to hold for a Reynolds number up to 75. Three methods are given for determining the average bead diameters.
On Vector Sums and Products
Authors: Klamkin Murray S.
Published: August 2005

The usual expressions for the vector sum, scalar product, and vector product of two vectors are derived from postulated properties having direct physical significance.
Matrix Calculus and the Stokes Parameters of Polarized Radiation
Authors: Walker M. J.
Published: August 2005

The specification of the state of polarization of beams of radiation by Stokes parameters is discussed. Mueller's method of regarding the Stokes parameters as column matrices and optical devices as represented by 4×4 matrices is described and examples of the procedure are given. The relation of the Stokes parameters to the Poincaré sphere representation is shown.
The Michelson Museum
Authors: Plum William B.
Published: August 2005

The Michelson Museum, located in the Michelson Laboratory, U. S. Naval Ordnance Test Station, Inyokern, China Lake, California, contains Michelson's early research apparatus, original manuscripts and research notes, reprints of published research papers, photographs, the Michelson medals, and the parchment announcing the late Dr. A. A. Michelson as the recipient of the 1907 Nobel Award in Physics. This paper contains a brief description of the items on display, one of Michelson's favorite portraits, and photographs of the Michelson medal case and the Museum.
A History of the Physics Laboratory in the American Public High School (to 1910)
Authors: Rosen Sidney
Published: August 2005

This paper attempts to trace the development of the American high-school physics laboratory from its beginnings in the early 1800's to its culminating domination of the science-teaching scene in 1910. An effort has been made to follow lines of educational and scientific thinking during the successive stages of development, so that a total picture of the cultural and social forces that shaped this form of science education emerges.
A Direct Experimental Method of Measuring the Ampere in Absolute Units
Authors: Ainslie D. S.
Published: August 2005

The balance described in this paper was employed, in preliminary experiments, to determine factors governing the force between parallel electric currents. It was then employed to measure the ampere in absolute units. A current range of 4.0 to 6.0 amperes was used in the work and the results obtained as described in the paper indicate an average error of 0.3 percent.
Physics Textbooks: Annuals or Perennials?
Authors: Blüh Otto
Published: August 2005

The paper deals with present-day physics textbooks and the way in which they are being used. It criticizes the current practice of treating nearly all textbooks as ephemerals, and the suggestion is made that a basic general and comprehensive physics text should find a more lasting place in the education of the scientist.
The Ionization Maintained in a Gas Before a Thin Plane Uniform Circular Source of Ionizing Particles
Authors: Fraser P. A.
Published: August 2005

An expression is derived that gives a good representation of the volume rate of production of ion pairs in a gas before a thin plane circular uniform source of ionizing particles. The expression is valid when the radius of the source disk is restricted to be less than one-quarter of the range at maximum ionization of the particles. This is not a severe restriction for practical cases.

Curves and a table of this rate are given, in which distances are in units of the radius of the source disk, and hence are of general applicability within the restriction on the source disk radius.

This work has application to a number of fields, among them the study of the optical radiation from the region in front of such a source.
Valence Bond Calculations
Authors: Schmid L. A.
Published: August 2005

The nature of the binding in molecular and ionic crystals and in metals is briefly discussed from an intuitive point of view. The salient features of the Slater-Pauling theory of the valence bond are then developed by generalizing the results of the Heitler-London treatment of the hydrogen molecule. The application of the theory to the calculation of the cohesive energy of diamond, the classic example of a valence crystal, is then discussed.
Techniques and Applications of Neutron Diffraction
Authors: Wilkinson M. K.
Published: August 2005

A brief review is given of the advances which have been made in the field of neutron diffraction during the past several years. The experimental techniques that have been developed are discussed, and illustrations are cited of several fields of application where information is obtained which would be very difficult or impossible to obtain by x-ray or electron diffraction.
Photonuclear Reactions
Authors: Berman Arthur I.
Published: August 2005

The significant aspects of photonuclear processes are reviewed in terms of the trends in research since their discovery in 1934. Experimental techniques with high-energy x-radiation, which are currently employed in these investigations, are described.
Systems of Units in Mechanics—A Summary
Authors: Bullock M. Loren
Published: August 2005

The theoretical basis and the historical background of five systems of units are described: the British gravitational system, the British absolute system, the metric absolute (cgs) system, the metric gravitational system, and the mks system. No one system is considered superior to any other, for each one has its advantages and its usefulness. It is shown that a law of physics can have exactly the same form in each of the five systems, but common practices are described in which this principle is not maintained. It is suggested that a student needs to see the complete picture of the systems, and that this should be presented as early in the physics curriculum as possible.
Experiments on the Laws of Light Absorption
Authors: Blüh Otto , Ko Howard
Published: August 2005

Attention is called to the importance of an experimental study of the laws of light absorption in the intermediate and advanced physics laboratory. A simple arrangement is described for measuring the absorption coefficients of solids and liquids, and suggestions are made for various experiments with commercial apparatus.
An Interpretation of the Variable Mass in Wessel's Theory of the Electron
Authors: Czyzak S. J.
Published: August 2005

The work of Dirac, Bopp, Hönl, and Wessel on the theory of the electron is briefly reviewed. The equations of motion, with a variable rest mass, are integrated to obtain the velocities. The initial condition in this development can be so chosen that one obtains a motion which is analogous to the “zitterbewegung” first derived by Schrödinger. The connection between spin and radiation reaction force is clarified.
Presentation of the Oersted Award to Professor Clifford N. Wall
Authors: Zemansky Mark W.
Published: August 2005

Remarks made on the occasion of the presentation of the Oersted Award to Professor Clifford N. Wall.
Some Elementary Concepts in Electrostatics
Authors: Frood D. G.
Published: August 2005

This note points out that Gauss's law is insufficient, except in special cases, to solve simple problems in electrostatics. In any system of dielectrics and charged conductors an additional condition, viz., that the total free energy is at a minimum is necessary to determine the equilibrium values of the fields. As will be seen, this requirement amounts to the statement that in electrostatics the potential across any conductor is continuous. For the sake of generality, the permittivities of the dielectric media are considered to be inhomogeneous, temperature dependent and also field strength dependent. The last property being included in case some (or all) of the dielectrics have the perovskite structure as, for example, in the titanates, tantalates, niobates, zirconates, etc. Consideration is given to interesting special cases of the generalized results.
A Note on the Design of the Spherometer
Authors: Chen Henry S. C.
Published: August 2005

A discussion is made of the errors involved in the use of a spherometer, and it is shown that the accuracy is limited by the accuracy with which the radius of the base circle is measured. A suggested change in design is given, which promises to mean easier manufacture and higher accuracy.
The Stroboscopic Effect and the Barber-Pole Illusion
Authors: Dodd Laurence E.
Published: August 2005

Mathematically and experimentally this paper shows that the visual stroboscopic effect has as a limiting case the barber-pole illusion. The conclusion is reached with primary emphasis on physical stimulus rather than psychological, including physiological, response. The treatment is from the teaching standpoint. For readers unfamiliar with the stroboscopic effect its essentials are given in detail.
On Planck's Quantum of Action
Authors: Epstein Paul S.
Published: August 2005

It is shown by means of dimensional analysis that both the Stefan-Boltzmann law and Wien's displacement law imply the existence of Planck's constant of action or of an equivalent constant.
Teaching of Electric Circuits and Dual Electric Circuits
Authors: Ikenberry E. , Rutledge W. A.
Published: August 2005

Electric network elements are defined. Methods for analyzing electric networks, both on the loop basis and on the node basis, are stated and illustrated by simple examples. The conventional method of constructing dual circuits, by drawing lines connecting loop centers, via the elements, is dualized, resulting in a construction in which loops, passing through the elements, are drawn around nodes. “Nominal voltage sources” are introduced to represent the voltages induced by mutual induction, making it possible to extend the reciprocal property of duality to all planar circuits.
The Measurement of Laboratory Achievement. Part II. Paper-Pencil Laboratory Achievement Tests
Authors: Kruglak Haym
Published: August 2005

This report deals with the analysis of paper-pencil laboratory tests in general physics, constructed and administered at the University of Minnesota, 1952–1953. The characteristics of the tests were investigated and the relationships with other achievement measures were explored.

With the exception of the Identification and Function, pretest intercorrelations were low. These two pretests were fair predictors for the corresponding posttests in Mechanics. All the pretests in Electricity were fair predictors for the corresponding posttests. The correlations between the paper-pencil tests and other criteria of achievement in elementary physics were either nonsignificantly different from zero, or low. On three of the four tests in Mechanics, boys scored significantly higher than girls. On all the posttests the means were significantly higher than for the pretests, irrespective of sex or course taken.

The investigation lends support to the hypothesis that paper-pencil laboratory tests contain elements other than those evaluated by performance tests and the conventional measures of achievement in elementary physics.
A Method of Exhibiting Sound Diffraction Patterns
Authors: Howe P. L. , Neilsen I. R.
Published: August 2005

The usefulness of the Schilling-Whitson sound diffraction apparatus is enhanced by mounting a small lamp on the detecting microphone. This allows the observer to correlate better the position of the microphone with the intensity of the sound. Photographic prints of the sound pattern can be made by focusing light from the lamp on to a sheet of photographic paper. For classroom use, copies of the sound-pattern prints mounted on pieces of cardboard, large enough so that the positions of the radiating apertures can be indicated, have proved useful.
A Laboratory Experiment on the Velocity of Light
Authors: Palmer C. Harvey , Spratt George S.
Published: August 2005

Apparatus is described which permits direct measurement of the velocity of light with about 1 percent error. The experiment is patterned after the precision method of Anderson using a Kerr cell and interferometer, but is much simplified. The optical parts used are of the kind usually available in small colleges, and the electronic components were built chiefly from war surplus material. The experiment is designed for undergraduate instruction with emphasis on simplicity rather than precision.
Problems Encountered in Routine Use of 10-Kilocurie, Gamma-Radiation Source
Authors: Nehemias John V. , Brownell L. E. , Meinke W. W. , Harmer D. E.
Published: August 2005

During a year of routine use of a 10-kilocurie, gamma-radiation source, operational problems have been encountered in control of radiation levels in nearby areas, control of pH and clarity of the water in the source storage well, breakdown of organic plastics under prolonged irradiation, and a discrepancy between nominal and apparent source strength. A short discussion of these problems and the resulting changes in operational procedures is presented.
Balance between Teaching and Research in the Independent College
Authors: Michels Walter C.
Published: August 2005

A wealth of research potential exists in the independent colleges of the country, yet it has been tapped only to a slight extent in comparison with the way in which the capabilities of the universities have been exploited. To convert this potentiality to actuality, we need financial support of a somewhat different type from that commonly available at present. Some of the conditions which must be satisfied, both by sponsors and by the colleges, are discussed.
Inertia of Energy
Authors: Kantor Wallace
Published: August 2005

The principle of the inertia of energy is a conclusion of the relativity theory that has far reaching consequences, in that it consolidates the laws of conservation of mass, momentum, and energy into one conservation expression. A brief historical discussion of the conservation laws and of the classical concept of the flow of energy is followed by several mathematical derivations and interesting examples of the inertia of energy. Where possible an heuristic approach is used.
On the Functions and Mission of the American Association of Physics Teachers. Problems and Proposals
Authors: Schilling Harold K.
Published: August 2005

This Association has to its credit many enviable achievements. It is suggested, however, that the present concepts as to its purpose and mission are inadequate for the future. Thus far in its history it seems to have been conceived of mainly an as association to hold meetings, to publish a journal, and to prepare, file, and occasionally publish committee reports. Having in mind the individual teacher, it has tried to give him encouragement, recognition, and inspiration, and opportunities to exchange ideas and experiences with his fellows.

The Association should become, to a much larger extent than in the past, an association for concerted and organized group study and action. Its goal should be to make of physics teaching a profession in the sense that law and medicine are professions. This will require more than that the Association give aid and encouragement to the individual teacher who endeavors to become more effective. It will require planned, systematic, and united attacks upon the problems of the profession as a whole and cooperative attempts to find solutions to such problems. It will require that the Association assert itself as the authoritative interpreter and official representative of physics teaching before the general public, other professional organizations, and government agencies; constitute itself a potent pressure group in behalf of our profession; help aggressively to maintain high professional standards; help improve conditions under which physics teachers must work; conduct cooperative educational experimentation and systematically attempt to improve physics teaching; collaborate with other agencies of higher education.

The past and current organization and modes of operation of the Association are not especially suitable for the realization of such purposes. Modifications and changes in these areas are suggested.
Classical Model for Rotational Magnetic Moments in Molecules
Authors: Jen C. K.
Published: August 2005

The classical model for rotational magnetic moments in molecules is useful for elucidating physical description, although it must give way to quantum mechanics for fundamental formulation. A powerful method of approach, first applied to the problem by Wick, is afforded by the generalized theorem of Larmor, which is here derived from the equations of motion for a rotating molecule placed in a magnetic field. It is shown that the electronic motion relative to the nuclear frame must be perturbed by the Coriolis torque as a consequence of molecular rotation. The rotational magnetic moment of the molecular electrons can be considered to consist of two parts, one due to “rigid” motion together with the nuclear frame and the other to “nonrigid” motion, which is equivalent to that created by a magnetic field in a nonrotating molecule according to the relation H = −ω/γ.
Some Notes on the Dynamic Load Factor in Simple Undamped Linear Systems
Authors: Saelman B.
Published: August 2005

It is shown that for linear undamped motion the dynamic load factor will not exceed 2 when the forcing function is monotone nondiminishing or nonincreasing. Similarly, if the first relative maximum of x is its absolute maximum, the dynamic load factor will not exceed 2. A few cases are illustrated for which the load factor ranges between zero and an indefinitely large value.
Finding the External Force
Authors: Phillips Thomas D.
Published: August 2005

Ambiguity in the statement of Newton's first law of motion occurs in most introductory physics texts. This is due to vagueness or inconsistency in the use of the word body. To make the statement of the law plain in meaning three revised wordings are available. In the opinion of the writer the best solution is to substitute the phrase, the center of mass of any body in the place of the common phrase every body.
Shock Waves in Gases
Authors: Griffith W. C. , Bleakney Walker
Published: August 2005

This paper is in part a review but it also contains some original work. It deals with the manner in which shock waves are formed from finite compressions in gases and describes something of the structure of the shock front itself. The principal features of the behavior of shocks in reflection, refraction, and diffraction are discussed with particular attention given to anomalous observations and comparison with simple theories. Some results are given for shocks in real molecular gases showing relaxation effects. Quite a number of illustrations are included from the authors' own observations in the shock tube. The treatment is not exhaustive but covers many points likely to be of interest to teachers of physics.
Phase, Group, and Signal Velocity
Authors: Weber J.
Published: August 2005

Phase, group, and signal velocity are defined. Simple examples are given in which the phase and group velocities exceed the velocity of light, in which the phase velocity is a function of distance, and in which the group velocity is equal to the signal velocity.
Analyzing Wave Forms in ac Networks
Authors: Carney Rose A. , Scheiber Donald
Published: August 2005

An electronic wave analyzer designed primarily for classroom teaching in electronics is described in detail. The analyzer is essentially a two-stage audio amplifier which contains series resonance loads tunable to frequencies between 300 and 2000 c/sec. Its purpose is to demonstrate Fourier's theorem visibly; namely, to show that any periodic voltage or current wave can be resolved into sinusoidal waves of various amplitudes and phases, whose frequencies are integral multiples of the lowest frequency present. Other electronic principles are demonstrated and a method for producing amplitude-modulated waves is shown.
The Tangential Drag of a Soap Film
Authors: Satterly John
Published: August 2005

A thin-walled hollow cylinder is suspended by a fine torsion wire so that it penetrates a horizontal soap film stretched across the top of a cup. The cup is rotated at a steady speed. The film drags the cylinder around until further deflection is stopped by the torsion reaction of the wire. From the known dimensions of the cylinder and the torsion constant of the wire the drag is shown to be of the order of 0.04 dyne per cm. The measurement of the tangential drag of a soap film is suggested as an advanced undergraduate laboratory project.
Three Interesting Instances of Rocking
Authors: Satterly John
Published: August 2005

(1) Two equal thin circular rings are firmly jointed together at one point so that their planes are inclined to each other. The combination is placed on a rough horizontal plane and made to rock to-and-fro. The period is calculated and confirmed by experiment. Repetition is made with jointed disks.

(2a) A right solid cone is suspended by the vertex from a fixed point on a rough vertical plane. It is made to rock through small oscillations. The period is calculated and confirmed by experiment. (2b) A right solid cone results in equilibrium on a rough plane inclined to the horizontal. It is set rocking and the period calculated and confirmed by experiment. Repetition is performed with a thin conical shell.

(3) A thin circular ring is placed standing on a rough horizontal plane and leaning against a rough vertical wall. It is set rocking to-and-fro and the period calculated and confirmed by experiment. Repetition is made with leaning disks and wide bands. Variants of (3) are also performed.
Elementary Laboratory Instruction in England
Authors: Brown Sanborn C.
Published: August 2005

A firsthand survey was made of elementary laboratory instruction at a number of universities in Great Britain. The British type of experiments, laboratory examinations, and teaching techniques are discussed. English undergraduate laboratory education is compared with the American system. English students do many more experiments and spend in the laboratory well over twice as much time as students in America spend. The British put a great deal more emphasis on the details of technique, and carry out more experiments on viscosity, surface tension, and thermal properties than is customary in America. Certain generalizations are drawn from this study which can guide the planning of elementary courses in this country.
Maxwell Commutator Bridge for Permittivity and Speed of Light
Authors: Palmer C. Harvey
Published: August 2005

An experiment is described which enables the student to measure the permittivity of space and the speed of light by means of the Maxwell commutator bridge. The part of the apparatus which had to be specially constructed consists of a 1000-cps electrically driven tuning fork switch and a parallel plate capacitor without guard rings but arranged so that the edge correction could be calculated. The rest of the essential apparatus is generally on hand in the laboratory or else can be purchased at reasonable cost. The accuracy of the experiment is limited chiefly by the accuracy of the construction of the capacitor. The results obtained have given the speed of light to within 0.5 percent.
Statistical Fluctuations at Very Low Temperatures
Authors: Band William
Published: August 2005

Standard formulas for fluctuations in a grand ensemble are used (i) to obtain a new reciprocal relation between density and pressure fluctuations at critical points, including the transition temperature in a Bose-Einstein gas, (ii) to discuss the fluctuations in population of the superfluid in the Bose-Einstein theory of liquid helium, and (iii) the energy fluctuations in liquid helium and in Debye crystals. Except for a Fermi-Dirac electron gas, all relative fluctuations become infinite as T→0°K. The paper discusses briefly the significance of these results with regard to (a) the interpretation of second sound in liquid helium, and (b) the state of equilibrium near absolute zero.
Emergency Ascent of an Undersea Diver from Great Depths
Authors: Schenck Hilbert
Published: August 2005

The ascent of a diver following sudden failure of his equipment is analyzed using basic physical concepts. It is shown that if he can begin his escape from the depths with a lung full of fresh air, he can expect to surface safely from depths in excess of 100 feet, even though the time of rise may be two minutes or longer. It is also shown that the most dangerous point of such an ascent is not as the surface is approached, but at a specified intermediate depth.
Inexpensive Michelson Interferometer
Authors: Cave Eric F. , Holroyd Louis V.
Published: August 2005

The construction and operating characteristics of a Michelson interferometer designed on kinematic principles are outlined. The main components are ground steel dowel pins and ball bearings which are commercially available. The construction requires only a moderate amount of mechanical skill. Preliminary results indicate that the device is quite suitable for use in the undergraduate optics laboratory.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 66. Fifteenth Century Paintings in American Galleries in Which Spectacles Appear
Authors: Watson E. C.
Published: August 2005

At least one famous fifteenth century painting in which spectacles appear is now on exhibit in this country. It is reproduced in this article in order to call its existence to the attention of physicists.
Method for Determining the Ratio of Planck's Constant to the Charge of the Electron Employing AC Amplification
Authors: Landegren G. F.
Published: August 2005

Filtered pulsating light from a mercury vapor lamp operated on ac is directed upon a commercial high-vacuum phototube, and the photocurrent, which is thereby pulsating dc, is passed by an ac amplifier whose output is fed to a dc milliammeter through a copper oxide rectifier. Using different light filters a retarding potential of increasing magnitude is applied to the phototube until the milliammeter readings reach respective minimum values which are plotted as ordinate against optical frequency as abscissa. The slope of the resulting line is taken as h/e.
Carnot's Version of “Carnot's Cycle”
Authors: Kuhn Thomas S.
Published: August 2005

The desirability and the difficulty of retrieving modern scientific concepts in classical scientific authors is discussed with particular reference to a recently published re-evaluation of Sadi Carnot's memoir. Evidence is presented to support the interpretation of Carnot provided by his nineteenth-century successors and current in modern texts: Carnot's use of the material theory of heat led him to misconstrue the foundations of thermodynamics, but the misconstruction, discoverable only in retrospect, is irrelevant to his stature as a profound and original investigator.
On “Some Current Misinterpretations of Carnot's Memoir”
Authors: Hirshfeld Martin A.
Published: August 2005

Although Carnot's contributions to thermodynamics have been universally recognized, it is usually with the reservation that there were serious gaps in his proof. Careful study of his memoir shows that Carnot implicitly defined heat so as to make it equivalent to entropy. With this interpretation it may be shown that his logic was flawless, that he believed in the kinetic nature of heat, and that his theorems are based on the first and second laws of thermodynamics.
Measurement of the Ohm in Absolute Units
Authors: Ainslie Donald S.
Published: August 2005

This paper describes an experiment for the measurement of resistance in absolute units, based on the bridge method developed by H. L. Curtis and R. W. Curtis [Bur. Standards J. Research 12, 665–734 (1934)]. The main modifications introduced in the work were the use of a mica instead of an air capacitor, a simplified method of measuring its capacitance in terms of resistance, and the use of the Anderson bridge in place of the Maxwell-Wien bridge for the determination of a relation between capacitance and inductance. A simple formula accurate to 0.4 percent was derived for the evaluation of the inductance of the single layer solenoid used in this work.
Centroidally Bordered Bodies and the Balancing L
Authors: Melvin M. A.
Published: August 2005

The preparation of bodies which have the property that the mass center lies on the periphery is here considered. It is demonstrated that, starting from a large variety of shapes, including all those here called “medially convex,” it is always possible to prepare a centroidally bordered shape by cutting a simple triangular notch out of the basic shape. Incidentally it is proved that every area which is medially convex with respect to a base b is at least 8/3 times as great as the area of the centroid triangle constructed on the base b. The method of triangular notching is applied in detail to several familiar shapes, including the general trapezoid and circular segment. The preparation of a centroidally bordered shape from a basic shape which includes a straight angle in its boundary is also considered. The solution by quadrilateral notching is indicated but not carried through in detail. The simple solution for the special case of the balancing L is written down and illustrated photographically.
Numerical Coincidences in Microphysics and Cosmology
Authors: Zimmerman E. J.
Published: August 2005

If nuclear lengths, masses, times, energies, actions, etc., are compared with corresponding cosmological quantities, the resulting dimensionless ratios are near unity or near a small, half-integral power of 1080, which is picturesquely called the “number of particles in the universe.” These “numerical coincidences” are collected and shown to imply probably a single relation between atomic and cosmic structural constants. They may be used to define two systems of units such that any quantity has a measure in the “elementary” system which is an integral power of 1040 times its measure in the “cosmical” system. Both systems are theoretically convenient, the “elementary” having c and h unity, and the “cosmical” having c and G unity.
Calorimetric Determination of Absolute Temperature
Authors: Bancroft Dennison
Published: August 2005

An undergraduate experiment is described for determining thermodynamic temperature directly from the definition of entropy. A simple system is arranged so that the entropy change due to the addition of heat may be calculated from the resulting change in the pressure exerted by the system. For this calculation the isentropic thermal expansion of the system must be determined experimentally. It is shown that in principle the temperature as determined does not require calibration of the thermometer used except at two fixed points. Accuracy of the order of 1 percent can be attained.
Certification of Physics Teachers
Authors: Lefler R. W.
Published: August 2005

Certification of physics teachers involves more than appropriate regulations. Members of college and university physics departments must participate in training good students for teaching positions in the schools. The development of appropriate state regulations and their intelligent interpretation into programs of study effective in producing physics teachers, who are to a degree scientists, involves effort on the part of physicists.

This paper reports on work in physics teacher certification initiated and to a large extent carried out by K. Lark-Horovitz, Head of the Department of Physics at Purdue and first Chairman of the AAPT Committee on the Teaching of High School Physics.
Reproduction of Prints, Drawings, and Paintings of Interest in the History of Physics. 68. A Group Portrait of Faraday, Huxley, Wheatstone, Brewster, and Tyndall
Authors: Watson E. C.
Published: August 2005

An interesting assembly of nineteenth-century scientists is here reproduced. It is likely, however, that it was not made from life, but was assembled from separate photographs.
Physics and Culture
Authors: Blüh Otto
Published: August 2005

A review and discussion of George Sarton's new books Ancient Science through the Golden Age of Greece and A Guide to the History of Science with added reflections on the teaching of the history of physics.
Laboratory Course for Seniors in Physics
Authors: Fitzsimmons K. E.
Published: August 2005

A laboratory course especially organized for college seniors is described and remarks concerning its administration and improvement are set down along with some general ideas concerning the laboratory training of senior physics students.
Simple Demonstration of Oscillatory Phenomena
Authors: Mouzon J. C.
Published: August 2005

A simple and inexpensive vacuum tube circuit is presented which is suitable for demonstrating elementary oscillatory phenomena at a frequency of about 14 cycle per second. With this equipment, it is possible to follow visually, on a meter or recorder, the individual excursions of the system.
Ferroelectricity
Authors: Vernon Robert C.
Published: August 2005

A general description of the phenomena of ferroelectricity is given together with a brief history of the subject. A comparison is made between ferroelectricity and ferromagnetism. Next, a more detailed description is made of the properties of the three main types of ferroelectrics:the barium titanate, KDP (potassium dihydrogen phosphate), and Rochelle salt types. Finally the electrical properties of these substances are discussed in relation to their crystal structures.
Physics in Engineering Education: ASEE 1954 Annual Meeting
Authors: Potter J. G.
Published: August 2005

This is a report of sessions in which engineers and physicists met to consider possible re visions of physics instruction in engineering education. The Interim Report of the ASEE Committee on Evaluation of Engineering Education and the responses of physics departments to a questionnaire prepared by committees of ASEE and AAPT provided the chief bases for the discussion.
Infrared Solar Spectrum
Authors: Goldberg Leo
Published: August 2005

An account is given of recent results obtained from the study of the infrared solar spectrum with modern grating spectrometers and detectors. The discussion is divided into three parts, namely, the sun's continuous spectrum, the solar absorption-line spectrum, and the telluric- or terrestrial-line spectrum.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 69. The Earliest Diagram of an Optical Instrument Other than a Spectacle Lens
Authors: Watson E. C.
Published: August 2005

If we may except the spectacle lens, the earliest device worthy to be called an optical instrument was the camera obscura. A remarkably fine diagram of this instrument, given by Leonardo da Vinci, is reproduced here. It is probably the earliest delineation of an optical instrument that we have.
Concerning the Rutherford Scattering Formula
Authors: Gordon M. M.
Published: August 2005

Working directly from the impulse-momentum theorem in combination with the angular-momentum equation, Rutherford's formula is derived without making explicit use of the trajectories of the scattered particles. This derivation is noteworthy in that it specifically demonstrates the special nature of the inverse-square-law force in classical scattering theory.
Electrostatic Strong-Focusing Lens
Authors: Bullock M. Loren
Published: August 2005

The basic principles of an electrostatic strong-focusing lens are described in order to illustrate a modern application of several classical concepts. The motion of an ion in the electrostatic field is described in terms of optical analogies to thick lenses. The astigmatism of such lenses is discussed, and the two-section lens designed for use with the Naval Research Laboratory 5-Mev Van de Graaff proton beam is described.
Problem of the Stillson Wrench
Authors: Northover F. H.
Published: August 2005

There seems to be some difficulty in understanding the basic principles underlying the working of the Stillson type of wrench, and the object of the present article is to elucidate these from considerations of elementary statics. It is found that such considerations suffice to give an explanation of the way in which the wrench works, and an attempt is made to give a measure of the efficiency of the wrench by deriving the “torque magnification factor.”