Volume 32, Issue 5, May 1964
Index of content:
32(1964); http://dx.doi.org/10.1119/1.1970330View 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 in 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. Such communications should be sent 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 Scr-1 and enclose a stamped return envelope.
32(1964); http://dx.doi.org/10.1119/1.1970334View Description Hide Description
Information is quantitatively defined in terms of probability, and the statistical interpretation of entropy is given. Entropy change and information are shown to be related on a physical basis, treating a simple volume expansion as an example. Maxwell's demon is discussed as an example of an irreversible process. The argument used by Brillouin in his discussion of the demon is corrected. A generalized second law of thermodynamics is set forth.
32(1964); http://dx.doi.org/10.1119/1.1970337View Description Hide Description
Ter Haar has shown that simple kinetic theory arguments based on Drude's early work can be used to derive approximate expressions for the transport properties of semiconductors and metals. Using ter Haar's ideas, this paper derives an expression for the ambipolar diffusion contribution to the electron thermal conductivity. In the first part of the derivation a general expression is obtained for the heat conductivity, using the concepts of the kinetic theory of gases and assuming an electron mean free path. The expression obtained is in all respects similar to the diffusionequation from the kinetic theory of gases, except for a term taking the effect of an electric field into consideration. In the second part of the derivation the concepts of band theory and semiconductor statistics are introduced in the kinetic theoryequations. The final expression for the ambipolar contribution, using Boltzmann statistics agrees, except for numerical constants, with the exact form derived from considerations based upon the Boltzmann transport equation. The application of Fermi-Dirac statistics to the problem yields no ambipolar diffusion term as a correction to the conductivity, if terms higher than the first order of the reciprocal of the reduced Fermi level are neglected. This is in agreement with the exact results based upon the Boltzmann transport equation from which it is seen that the ambipolar term contains only second and higher order terms of the reciprocal of the reduced Fermi-level.
32(1964); http://dx.doi.org/10.1119/1.1970340View Description Hide Description
It is observed that the free-energy,susceptibility, and correlation functions for a linear chain of N spins with nearest-neighbor isotropic Heisenberg coupling can be calculated explicitly in the (classical) limit of infinite spin. The results are compared briefly with those for Ising and Heisenberg chains of spin .
32(1964); http://dx.doi.org/10.1119/1.1970343View Description Hide Description
Contrary to a rather widespread belief, the Newton-Lorentz equation of motion does not exclude orbit solutions which represent the trapping of a charged particle which is externally injected into a region of time-independent magnetic field. Specific examples of such orbits are demonstrated. Theorems of Liouville and Poincaré are used to clarify the nature of the restrictions which classical mechanics imposes upon the injection and trapping of charged particles in a static magnetic field.
32(1964); http://dx.doi.org/10.1119/1.1970346View Description Hide Description
Some elementary experiments in geometrical and physical optics, usually limited to individual observations in the laboratory, can be adapted for presentation to larger groups as lecture or classroom demonstrations, by making use of the gas laser as light source. This paper describes several such experiments dealing with lens aberrations, interference and diffraction phenomena, and the Abbe theory of the microscope; together with some practical optical systems for performing them.
32(1964); http://dx.doi.org/10.1119/1.1970348View Description Hide Description
A magnetic resonanceexperiment is proposed which is suitable for a junior or senior undergraduate laboratory course. By use of a six-level spin system and simple detection equipment, a number of concepts may be emphasized which are unavailable to the usual NMR or ESRexperiment, and the physical content, as distinct from instrumentation, may be emphasized.
32(1964); http://dx.doi.org/10.1119/1.1970357View Description Hide Description
A detailed analysis is presented for the problem of uniform circular motion in which the centripetal force is provided by a stretched spring whose mass is not negligible compared with that of the whirling body. It is shown that the force required to stretch the spring statically to the length it has during the rotation exceeds the centripetal force it exerts on the whirling body by an amount depending in a simple way on the spring mass; the excess can be erased by adding to the body mass approximately one-third the spring mass in computing the centripetal force. Some experimental results that tend to support the theory are exhibited and discussed. A computation of radial-oscillation frequencies is included.
32(1964); http://dx.doi.org/10.1119/1.1970360View Description Hide Description
The conditions are set down, under which the stationary-state motion of a particle in a static field of force is the same according to the Schrödinger equation as in classical mechanics. Some solutions are found. All the cases obtained correspond to unbound states.
32(1964); http://dx.doi.org/10.1119/1.1970363View Description Hide Description
It is shown that conventional plane-polar coordinates can be extended to three dimensions. The result is that three-dimensional motion of a particle can be viewed as instantaneous planar motion plus a rotation of the plane of motion around the instantaneous radius vector from the origin to the particle. The kinematic and dynamic equations in this system are developed and applied to two examples, the spherical pendulum and a problem in orbit motion.