Volume 32, Issue 12, December 1964
Index of content:
32(1964); http://dx.doi.org/10.1119/1.1970011View Description Hide Description
Prepared at the request of the AAPT Committee on Resource Letters; supported by a grant from the National Science Foundation.
This is one of a series of Resource Letters on different topics, intended to guide college physicists to some of the literature and other teaching aids that may help them improve course contents in specified fields of physics. No Resource Letter is meant to be exhaustive and complete; in time there may be more than one letter on some of the main subjects of interest. Comments and suggestions concerning the content and arrangement of letters as well as suggestions for future topics will be welcomed. Please send such communications to Professor Arnold Arons, Chairman, Resource Letter Committee, Department of Physics, Amherst College, Amherst, Massachusetts.
Notation: The letter E after an item number indicates elementary level, useful principally for freshman liberal arts through sophomore physics courses; the letter I indicates intermediate (junior, senior) level; and the letter A indicates advanced material principally suited for senior, graduate study. An asterisk (*) indicates items particularly recommended for introductory study.
Additional copies: Available from American Institute of Physics, 335 East 45 Street, New York, New York, 10017. When ordering, request Resource Letter PhM-1 and enclose a stamped return envelope. A small booklet containing reprints of some of the fundamental references will soon be available for purchase from the American Institute of Physics.
32(1964); http://dx.doi.org/10.1119/1.1970014View Description Hide Description
In developing the ensemble theory of statistical mechanics, the thermodynamic temperature T, can be introduced in a direct manner avoiding the intermediate use of a Lagrange multiplier, if one adopts the Gibbs entropy postulate and uses a general criterion for thermodynamic equilibrium. This procedure is described in detail for both closed and open systems.
32(1964); http://dx.doi.org/10.1119/1.1970020View Description Hide Description
An apparatus is described in which the displacement current in a bariumtitanatecapacitor forms the primary of a toroidal transformer with a Permalloy core surrounding the capacitor. The voltage output of the transformer increases with the square of the frequency. At and a supply voltage of 50 V an output voltage of 50 mV is obtained.
32(1964); http://dx.doi.org/10.1119/1.1970023View Description Hide Description
A quasithermal, quasmonochromatic lamp is described which serves as a highly degenerate light source with adjustable coherence time between sec and 1 sec. This lamp is used for several demonstration experiments concerning the relations between coherence and fluctuations: The intensity interferometer of Hanbury Brown and Twiss is applied to measure the correlations between intensity fluctuations. The double slit experiment of Young serves to stress the role of fluctuations for classical interferometry. Interference patterns from two independent quasithermal lamps are presented.
32(1964); http://dx.doi.org/10.1119/1.1970026View Description Hide Description
Despite the undisputed importance attached to problem-solving activities in college and university physics courses, problem teaching methods have changed little since 1900. A possible explanation of this paradoxical combination of importance and stagnation is lack of awareness of the tremendous range of activities that problem work could provide for teaching students the skills and attitudes of creative physicists—if taught in a way very different from the usual methods of today. The plausibility of this explanation is enhanced by the critique of current problem teaching methods presented in this paper. Present-day methods are evaluated on the basis of six specific objectives of physics-problem teaching, derived from an analysis of the skills and attitudes involved when a creative physicist tackles a problem in his own work. It is shown that conventional methods aim at only one of these six objectives. A new approach, making use of open-ended problems and designed to attain all six objectives, is presented. It is illustrated by a detailed teaching sample and additional procedural remarks, in order to facilitate experimentation with the method.
32(1964); http://dx.doi.org/10.1119/1.1970029View Description Hide Description
32(1964); http://dx.doi.org/10.1119/1.1970031View Description Hide Description
There has been a considerable growth of interest in many aspects of plasma physics during recent years. This has been reflected in the introduction of new courses, or the expansion of old ones, in many colleges and universities to cater to the needs of students interested in this field. Laboratory experience constitutes an extremely valuable adjunct to teaching courses. There is, consequently, a considerable value in introducing experimental work wherever possible. This paper describes some laboratory experiments, requiring a minimum of expensive equipment, and which serve to introduce the student to useful diagnostic techniques which are founded on very basic models of plasma behavior. They have been tested in the laboratory and adopted for a laboratory instruction course given to graduateelectrical engineers and physicists at Stanford University.
32(1964); http://dx.doi.org/10.1119/1.1970033View Description Hide Description
The successful use of three films: Momentum of Electrons, The Ultimate Speed, and Time Dilation as “experiments” in the second year Physics Laboratory is described. The regular experiments in the laboratory are used to teach experiment design, measurement, and error calculation; and the film experiments were used to show how real physicists designed and performed their experiments using the same principles. The films also permitted the “use” of equipment not normally available to second-year students. Working in pairs, the students viewed the films, took data from the instruments shown, estimated the error in the measurements, then wrote up the experiment as a normal laboratory report. While the use of Momentum of Electrons as an “experiment” was not as successful as was this use of the other two films, the class was enthusiastic over all three films, and was unanimous in wanting at least one film experiment of this type each year.
32(1964); http://dx.doi.org/10.1119/1.1970036View Description Hide Description
If the rest mass is constant the equation of motion may be presented in the form: force equals time rate of change in momentum. However, if the rest mass varies because there is an influx or or efflux of mass, the equation of motion may include additional terms to account for the momentum flux. These terms are derived by applying the impulse-momentum principal and the work-energy principle. The relativistic equation of motion gives the thrust as a function of the influx or efflux velocity, the rate of mass flow, and the Lorentz factor for the system.
32(1964); http://dx.doi.org/10.1119/1.1970038View Description Hide Description
One segment of a course for nonscience majors using limited parts of Newton's Principia is described. The relevant source material is reviewed. The class studied in detail the proofs of some of the early theorems in the Principia, including the law of areas for central forces and the relation between forces and motion in conic sections. In spite of warnings in the literature, this was not too difficult; the students' background in geometry proved to be adequate to the task. It is suggested that it may be possible to follow a similar approach in high-school physics, or in the last several months of high-school geometry. In contrast with the usual course for nonscience majors and with most beginning courses in physics, Newton rapidly obtains important results. Using the Principia provides an introduction to the history of science in one detailed situation where some aspects of Newton's thought processes are examined.