Volume 28, Issue 3, March 1960
Index of content:
28(1960); http://dx.doi.org/10.1119/1.1935098View Description Hide Description
We describe the National Science Foundation supported V.F.S.P. for institutes for secondary school teachers of science and mathematics, conducted for the first time in the summer of 1959. The need for the program stems both from the international nature of science itself and from the lag in our present secondary school science education. It is emphasized that lectures on recent advances in physics can be made more effective by organized programs such as the V.F.S.P. A briefing session is most important. Highlights of the visits' evaluation are followed by an introduction to the twelve papers constituting the heart of the project report. The fields of physics included are thermodynamics and molecular physics, low and high energy nuclear physics, thermonuclear physics, cosmic rays, three topics in solid state physics and metallurgical physics.
28(1960); http://dx.doi.org/10.1119/1.1935099View Description Hide Description
28(1960); http://dx.doi.org/10.1119/1.1935100View Description Hide Description
Physics is one aspect of the science which deals with nonliving matter. It is concerned primarily with general principles valid either for all kinds of material, as for example gravitation, or relating to laws in which matter as such does not come in directly ; for example, the propogation of electromagnetic waves in a vacuum. However, the boundary between physics and chemistry in common parlance is largely historical in origin.
Physics is a great triumph of the human mind, but it has often grown from the study of apparent trivialities. That these can lead to the most important discoveries is itself one of the great discoveries of the scientific method. There is as yet no all-embracing physical theory, and as knowledge increases the significance of the partial theories is seen to change, but they are seldom entirely superseded. Even a successful universal theory would leave much to do; the consequences of theories are deemed worthy or unworthy of study for aesthetic or practical reasons.
Nature is no longer considered to be deterministic in detail though it is in gross.
The practical value of physics showed itself clearly in the development of electrical engineering, and now physics has become essential to a developing civilization.
Scientists are responsible for those consequences of their actions which reasonably can be foreseen, but the extent to which consequences can be foreseen is exaggerated. The different parts of a civilization are interlocked and it must be accepted or rejected as a whole.
28(1960); http://dx.doi.org/10.1119/1.1935101View Description Hide Description
It is shown how the results of compressibility measurements in gases and liquids lead to the hypothesis of molecular interaction, and how details about this interaction may be obtained from the experimental data for the equation of state. The reasons for the molecular interaction are found in the laws of electrostatics and quantum mechanics.
The problems the molecular physicist is interested in are threefold. He wants to understand molecular interaction from first principles, he tries to get information about this interaction from a variety of experiments, and he seeks to understand a large group of experimental observations once the interaction of the molecules is known. For the solution of the second and third problem it is usually necessary to link the macroscopic observables to the microscopic molecular properties; although this has been possible in some instances, the general problem cannot be solved.
28(1960); http://dx.doi.org/10.1119/1.1935102View Description Hide Description
This paper, which is itself in the nature of an abstract, discusses how one can gain an understandingof the basic concepts of classical (phenomenological) thermodynamics, usingvirtually no mathematics at all, and without the introduction of the usual artifices such asabstract engines, cycles, perfect gases, and so on.
28(1960); http://dx.doi.org/10.1119/1.1935103View Description Hide Description
In Sec. A, a review is given of the modification of the classical picture of forces and particles by the ideas of quantum theory leading to Yukawa's meson hypothesis. In Sec. B, some aspects of the present knowledge of the elementary particles and their interactions are discussed from a phenomenological point of view.
28(1960); http://dx.doi.org/10.1119/1.1935104View Description Hide Description
The paper gives some general information about cosmic rays, especially with regard to the properties of the primary flux: charge composition, energy spectrum, and time variations. The experimental evidence for these properties of the cosmic rays is outlined briefly and possible origins of the radiation are discussed.
28(1960); http://dx.doi.org/10.1119/1.1935105View Description Hide Description
The possibility of extracting energy in a controlled manner from the nuclei of deuterium holds out the hope of a permanent solution of the problem of the supply of energy. It involves heating the gas to temperatures in the 100-million degree range. The outstanding difficulty is to prevent the heat escaping. Inevitable loss by radiation can be accepted. Loss by conduction must be greatly reduced. This means using magnetic fields.
Among the methods that have been tried to contain a plasma, three are: the pinch discharge in which a large current is passed through the rarified deuterium in a torus; containment by magnetic mirrors in which the diamagnetic character of the plasma is used to exclude it from regions of high magnetic field; Spitzer's stellerator in which gas is contained by re-entrant lines of force due to currents outside the vessel which holds it.
Difficulties arise in all cases; for the pinch discharge and to some extent the stellerator, these are due to some of the many forms of instability which can affect plasma in magnetic fields ; for the magnetic mirrors to the poor containment at relatively low temperatures and to difficulties of injection. No method has yet been successful, but all these are very hopeful.
28(1960); http://dx.doi.org/10.1119/1.1935106View Description Hide Description
Some of the metallurgical problems in the construction of nuclear reactors are discussed. Typical problems resulting from neutron bombardment encountered such as uranium growth, deterioration of fuel cans, thermal effects, and radiation effects, are presented in detail. Solutions to some of these problems found during the construction of the Calder Hall reactor in the United Kingdom are given as examples of the complex problems encountered. Some of the basic solid-state effects due to neutron irradiation are still not fully understood and are being investigated.
28(1960); http://dx.doi.org/10.1119/1.1935107View Description Hide Description
The presentation of some fundamental ideas concerning the behavior of electrons in solids is followed by an outline of the theory of the use of x-ray methods for obtaining information about these electrons. Experimental methods are discussed briefly and some recent trends and developments in the subject are reviewed.
28(1960); http://dx.doi.org/10.1119/1.1935108View Description Hide Description
An elementary classification of crystals according to their binding forces shows that an ideal crystal, defined as a perfect lattice of spherical atoms held together with two-body, central forces, should be found among the inert gas solids. The calculation of a lattice energy from an interatomic potential of the Mie-Lennard-Jones form is discussed, and the results for the hexagonal and cubic close-packed lattices compared. For argon, it is shown that a (12,6) interatomic potential, whose constants have been calculated from the crystal parameters at 0°K, can be used to predict both the specific heat of the crystal and the second virial co-efficient of the gas over suitable ranges of temperature. A comparison of this interatomic potential with existing calculations of the interaction of two argon atoms shows that the macroscopic properties of argon can be calculated at present from a pair potential, but not directly from the properties of an argon atom.
28(1960); http://dx.doi.org/10.1119/1.1935109View Description Hide Description
The basic idea of paramagneticresonance is presented in terms of a simple classical mechanical model. The model is then elaborated to show how paramagneticresonance may be used to obtain information about atomic nuclei and the structure of crystals. A typical apparatus with which it may be observed is briefly sketched.
Graphical Derivation of the Inverse-Square Law of Gravitation from an Elliptic Orbit and Kepler's Law of Areas28(1960); http://dx.doi.org/10.1119/1.1935110View Description Hide Description
Motivated by the common knowledge that earth satellites move in elliptic paths, a graphical demonstration is presented which shows that if a small mass moves in an elliptic orbit about a large mass at one focus and obeys Kepler's law of areas, the force of attraction on it must vary inversely as the square of the distance between the two masses. The demonstration differs from the usual elementary proofs of the inverse-square law in that it assumes elliptic rather than circular orbits, uses the law of areas instead of the dependence of period on semimajor axis, and requires a minimum of formal mathematics. By using a similar construction it may be shown that if the large mass is at the center of the ellipse, the force varies linearly with distance.
Apparatus Drawings Project. Report Number 4. Air Suspension Apparatus for Measuring the Resolution of Forces28(1960); http://dx.doi.org/10.1119/1.1935111View Description Hide Description
The equipment to be described is a sailboat model designed for use in an undergraduate student laboratory for the quantitative investigation of the resolution of forces The “sailboat” floats on a cushion of air to reduce friction to a minimum. The force to be resolved, which may be applied from any horizontal direction, is the “wind,” supplied by a high-velocity blower. The experimental error is less than 5%.
28(1960); http://dx.doi.org/10.1119/1.1935112View Description Hide Description
This article comprises a set of three independent reviews of the 1958–1959 television presentation of a course in modern physics at about the college freshman level. There is a short introduction to the reviews by Robert H. Randall, Chairman of the Visual Aids Committee of the AAPT, pointing out the part played in the production by Dr. Harvey White, the chief lecturer, and also noting the occasional appearance of a number of prominent guest speakers. The joint sponsorship of the program is also described.
The three appraisals are supplied by Myron C. McCay of the University of Chattanooga, Truly C. Hardy of the City College, New York City, and Alan T. Wager of Arizona State University. In general, all three reviews pay tribute to the careful and effective handling of the subject matter by Dr. White and to the stimulation afforded by the presence of guest speakers. The lack of opportunity for discussion, inevitable with a television presentation, is stressed. A number of the guest speakers, in the view of the reviewers, spoke at too high a level. The course has apparently appealed to a large group of viewers well outside academic walls. In general, the venture is considered well worth the effort.
28(1960); http://dx.doi.org/10.1119/1.1935113View Description Hide Description
Students are influenced strongly by tests, because the tests are to them the basis of rewards for their efforts. Because of this, it is essential that attempts to emphasize methods, as well as subject matter coverage, in physics courses must include the construction of tests that require the student to demonstrate his knowledge of process or method as well as knowledge. Examples of the way in which this has been done in connection with the tests that accompany the Physical Science Study Committee Course are included.
28(1960); http://dx.doi.org/10.1119/1.1935114View Description Hide Description
The background and growth of the Advanced Placement Program are discussed. Construction, form, and grading of the examination are described. Some indications of the validity of the examination and acceptance by the colleges are presented. A number of problems still to be solved are posed.
28(1960); http://dx.doi.org/10.1119/1.1935115View Description Hide Description
The program of the National Science Foundation for the support of academic-year, summer, and in-service institutes is summarized and the place of physics in the various institutes is analyzed. Details are given as to dates at which proposals must be received, what type of financial help is available to institutions and to participating teachers, and as to the factors that all institutes have in common.
28(1960); http://dx.doi.org/10.1119/1.1935116View Description Hide Description
The physics course developed by the Physical Science Study Committee is outlined in some detail. Examples of the laboratory work and of the instructional films that accompany the course are included to show how these parts of the course are integrated with the text on the one hand and supplementary to it on the other.