摘要:

Several professional scientists at the University of California in Berkeley have established a collaboration with educators to study problems of science teaching in the elementary schools. The objective is to help educators prepare a scientifically and psychologically sound program for elementary school science instruction. Scientific subject matter is presented in an inductive problem-solving approach. The first year's experience with laboratory use of some teaching materials prepared with the guidance of the committee members revealed many problems, but was greatly encouraging as well.

ISSN:0002-9505    

DOI:10.1119/1.1941888

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

摘要:

Observations of the cosmic radiation arriving at the earth show that both the energy spectrum and total intensity of particles change with time. A brief survey is presented of the major changes in the flux of relativistic particles, with representative data from nucleonic detectors. The rigidity dependence and attenuation for the long-term change and transient variations are discussed. Some data for the sudden increases which represent solar injection are shown. The investigation of these intensity-time variations yields information about the electromagnetic state of the earth-sun region.

ISSN:0002-9505    

DOI:10.1119/1.1941885

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

摘要:

A description of the basic equipment necessary for instituting a nuclear laboratory is presented. A series of fundamental neutron experiments utilizing a neutron source and a neutronhowitzer are outlined.

ISSN:0002-9505    

DOI:10.1119/1.1941886

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

摘要:

The making of the two-dimensional printed circuit type models of current-carrying conducting systems and the use of these models for demonstrating the electric fields of current-carrying conductors is described. The models are produced by drawing the systems under consideration on glass plates using a transparent conducting ink. The electric lines of force inside and outside the elements of these models are demonstrated with the aid of grass seeds strewed upon them.

ISSN:0002-9505    

DOI:10.1119/1.1941887

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

摘要:

The problem of determining a spherically symmetric potential from its energy eigenvaluesEnin states of zero angular momentum is solved approximately. The corresponding problem for a one-dimensional potential is also solved. It is incidentally shown that the large eigenvalues depend only upon the width of the potential as a function of height rather than on its precise shape. The level spacingEn+1−Enis investigated for a one-dimensional potential. It is shown that the spacing does not increase faster thanEnfor large values ofEn. Thus the relative spacing(En+1−En)/Endecreases faster than1/Enfor largeEn. This fact is proposed as an explanation for the undetectability of quantization at high energies. It is also shown that of all potentials having a given width at the energyEand a given depth, the square well has the greatest spacing atE. The corresponding classical mechanical problems, which concern nonlinear vibrations, are also considered.

ISSN:0002-9505    

DOI:10.1119/1.1941889

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

摘要:

Sommerfeld has given an apparent case of a perpetual motion machine of the second kind. This consists of a Carnot engine employing liquid water and operating between the normaland anomalous regions of thermal expansion. His explanation of the paradox is shown to be incomplete when the temperature of maximum density is pressure-dependent. To analyze thiscase a simple thermodynamic model for a substance with a density extremum is given; this model yields a reasonable approximation to the data for water. Standard thermodynamicproperties of the system are computed and useful approximate forms given. Various Carnot cycles and a non-trivial “two-process” cycle are then shown in thep−T,T−s, andp−vplanes. Sommerfeld's paradox is resolved by showing that a Carnot cycle qualitatively similar to thatin his problem involvesexpansionsforbothisothermal processes. Theoretical implications of the analysis and applications to sound waves and shock waves are briefly discussed.

ISSN:0002-9505    

DOI:10.1119/1.1941890

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

摘要:

The concept of “the one-way experiment” is discussed and shown to be meaningless. It is furthermore shown that the pure information extracted from two-way experiments forces one to relinquish the notion of an aether-rest-frame as an operationally significant privileged reference frame. Great care is exercised in defining (spatial) coincidence and (temporal) simultaneity.

ISSN:0002-9505    

DOI:10.1119/1.1941891

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

摘要:

This paper outlines modifications in the bridge and resonant circuit method of measuring resistance in absolute units, as outlined by the author in a previous paper. These modifications simplify the experimental procedures without any loss of accuracy.

ISSN:0002-9505    

DOI:10.1119/1.1941892

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

摘要:

The specific heat of a free particle in a cubic box with reflecting walls is found to be a function of variableη = 2mL2kT/ℏ2(m = mass of particle, L length of box, T = temperature, k and 2πℏBoltzmann's and Planck's constants). For largeηthe specific heat approaches the classical equipartition valuedk/2(d = dimensionality), for smallηit approaches zero asT−2exp(−constT−1), and in between, atη = 9π, it has a maximum,(9/8)(dk/2).

ISSN:0002-9505    

DOI:10.1119/1.1941893

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

摘要:

The use of the magnetic pole in the development of the concepts of electricity and magnetism leads unambiguously to a relativistic formulation of the field vectors which is well within the grasp of the sophomore student. The development is wholly consistent with Maxwell's equations and leads to clear and understandable definitions of the field vectors both in vacuum and in the material medium, as well as to the relations defining the transformations of the field vectors.

ISSN:0002-9505    

DOI:10.1119/1.1941894

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP