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Dec 1952

Volume 20, Issue 9, pp. 527-599

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The Nuclear Reactor as a Research Implement

Arthur H. Snell

American Journal of Physics -- December 1952 -- Volume 20, Issue 9, pp. 527

Online Publication Date: Jul 2005

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Several of the more significant physical experiments which have been performed in recent years with nuclear reactors as measuring instruments or as neutron sources are described. The examples are selected partly because of their importance and partly with diversification in mind. Short descriptions are given of the pile oscillator method of measuring neutron absorption cross sections, the measurement of neutron capture gamma-ray spectra, the study of neutron resonances by time-of-flight, neutron diffraction, neutron reflection, and the radioactive decay of the neutron.

Experimental Production of a Divergent Chain Reaction

Enrico Fermi

American Journal of Physics -- December 1952 -- Volume 20, Issue 9, pp. 536 | Cited 1 time

Online Publication Date: Jul 2005

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Except for minor editorial revisions this paper is the reproduction of a report written for the Metallurgical Laboratory of the University of Chicago almost ten years ago, after the experimental production of a divergent chain reaction. This report has now been declassified and can be published.
The present first part of the report contains a general description of the first pile and of its operation. The details of the construction, preparation, and testing of the materials and of the instrumentation are given by the members of the groups responsible for the work in Appendices I and II.
The pile had approximately the shape of a flattened ellipsoid of graphite having 388-cm equatorial radius and 309-cm polar radius. The uranium was distributed through the graphite mass in lumps partly of metal and partly of oxide arranged in a cubic lattice array with about 21-cm cell side. The experimental procedure followed in approaching the critical dimensions and in the actual operation of the pile is described. The observed critical dimensions are compared with the expectation from the tests on the various components of the structure.

A Demonstration of the Transformation of Mechanical Energy for Student Computation

Thomas J. Blisard and Charles H. Duursema

American Journal of Physics -- December 1952 -- Volume 20, Issue 9, pp. 559

Online Publication Date: Jul 2005

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This apparatus was designed to provide data for sustained computations by engineering students in general physics and consists of a large pendulum swinging over a waxed-paper strip. The velocities of the ball at a number of positions are computed, the kinetic and potential energies are calculated for each position and plotted against the angle of displacement of the pendulum. The sum of the two curves when plotted is a horizontal line. Students interpret the total mechanical energy curve in terms of the conservation of mechanical energy. Student interest is motivated by the impressive size, visibility, and precision of the apparatus. The effectiveness of the demonstration is enhanced by using procedures simulating an engineering situation.

On Definitions in the Teaching of Physics

Zeno V. Chraplyvy

American Journal of Physics -- December 1952 -- Volume 20, Issue 9, pp. 562

Online Publication Date: Jul 2005

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Reasons are discussed why certain rigorous definitions of physical quantities appear to be too difficult for the average student. A general criterion for pedagogically satisfactory definitions is proposed and illustrated by several examples; in particular, the definition of the magnetic field vector B by means of the Lorentz force is discussed in some detail. Remarks are added on the use of auxiliary “paradefinitions”

Integration as an Objective in the Physical Sciences

Ian G. Barbour

American Journal of Physics -- December 1952 -- Volume 20, Issue 9, pp. 565

Online Publication Date: Jul 2005

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The educational objective of integration or “insight into relationships of one's own field to other areas of life” is discussed. Several types of general education science course are compared in their attempt to present science in relation to other fields of human knowledge. A two-week unit is outlined dealing specifically with the impact of science on man's life and thought.

The First Reported Observations on Emission Spectra

E. C. Watson

American Journal of Physics -- December 1952 -- Volume 20, Issue 9, pp. 569

Online Publication Date: Jul 2005

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The first person to use a prism to examine the light from colored flames was a young Scot named Thomas Melvill. He announced his results in a paper read before a philosophical society in Edinburgh early in 1752, less than two years before his death at the early age of twenty-seven. This paper, which was not published until 1756, is so rare that it seems desirable to reproduce a portion of it in facsimile in celebration of the 200th anniversary of its reading.

Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 49. A Sixteenth Century Spectacle Shop

E. C. Watson

American Journal of Physics -- December 1952 -- Volume 20, Issue 9, pp. 578

Online Publication Date: Jul 2005

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This brief note reproduces a charming sixteenth century engraving of a spectacle shop. It is of especial interest to physicists because it shows at a glance how the practical discovery of the telescope and microscope came to be made.

Optical Filters

Nora M. Mohler and John R. Loofbourow

American Journal of Physics -- December 1952 -- Volume 20, Issue 9, pp. 579

Online Publication Date: Jul 2005

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In Part II of this survey of filters useful in optical work are included descriptions of polarization, interference, and Christiansen filters, and devices occasionally used in lieu of filters such as focal isolation and residual ray apparatus, gratings, and powder films used effectively as scatterers. Absorption type filters were surveyed in Part I.
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Let's Be More Specific

Donald M. Bennett

American Journal of Physics -- December 1952 -- Volume 20, Issue 9, pp. 589

Online Publication Date: Jul 2005

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An Experimental Verification of the Coulomb Law for Magnetic Poles

José Goldemberg

American Journal of Physics -- December 1952 -- Volume 20, Issue 9, pp. 590

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Focusing Aid for Photographic Enlarging and other Applications of Focusing without a Ground Glass

Albert V. Baez

American Journal of Physics -- December 1952 -- Volume 20, Issue 9, pp. 592

Online Publication Date: Jul 2005

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The Reality Problem in Quantum Mechanics

Olivier Costa de Beauregard

American Journal of Physics -- December 1952 -- Volume 20, Issue 9, pp. 593

Online Publication Date: Jul 2005

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Electrical Work in Thermodynamics

R. O. Davies

American Journal of Physics -- December 1952 -- Volume 20, Issue 9, pp. 593

Online Publication Date: Jul 2005

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Abstract Unavailable
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Western Pennsylvania Section

Richard C. Hitchcock

American Journal of Physics -- December 1952 -- Volume 20, Issue 9, pp. 598

Online Publication Date: Jul 2005

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