摘要:

A review of modern developments in magnetism with special attention to the magnetic effects in gross matter that have their origins in the magnetic moments of nuclei.

ISSN:0002-9505    

DOI:10.1119/1.1933596

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

From the teaching standpoint in general physics, the pendulum clock uncompensated for temperature change continues to offer valuable material. The present discussion emphasizes that although the oscillation rate is affected by thermal expansion or contraction, causing the clock to “lose” or “gain,” the behavior of the clock remains perfectly normal, that is, “correct,” controlled by physical laws. Consequently, the terms “correct” and “incorrect” should not be applied to period or temperature, but such terms as “standard” or “nonstandard” substituted for them. Attention is focused on the sharp distinction between indicated and actual elapsed time, withindicated seconds per vibration, a constant of the clock, as the key to a clear and general analysis. This constant equals the period only at the standard temperature.

ISSN:0002-9505    

DOI:10.1119/1.1933597

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

The differential thermometer was simultaneously discovered by Sir John Leslie and Count Rumford. The priority controversy between these two men is presented. Some years later Sir Humphry Davy depreciated Leslie's claim to the discovery. The ensuing debates cast interesting light on the personalities of the protagonists.

ISSN:0002-9505    

DOI:10.1119/1.1933598

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

A technique for presenting the concept of normal coordinates to the beginning student of mathematical physics is described. The method differs but slightly from that found in standard textbooks on mathematical physics. This slight difference has been found to be of great assistance to students who are encountering normal coordinates for the first time.

ISSN:0002-9505    

DOI:10.1119/1.1933599

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

The indiscriminate translation of the words “feu,” “chaleur,” and “calorique,” uniformly as heat (or wärme) in the accepted translations of Carnot's memoir, without recognizing differences in meaning which Carnot consistently implied, has led to erroneous misinterpretations of his thesis, which are prevalent in present day texts.Carnot had at least an intuitive conception of the modern interpretation of entropy in his consistent use of “chute de calorique” as analogous to “chute d'eau.” He never speaks of “chute de chaleur.”One needs only to identify “calorique” as entropy and “chaleur” as heat to achieve simplicity and lucidity in understanding his memoir and at the same time imparting accordance with modern theory for pertinent passages that have been misconstrued.

ISSN:0002-9505    

DOI:10.1119/1.1933600

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

Two fundamentally different explanations have been given in the literature to explain the “unusual” motion of a specially constructed spherical top in which rotation causes the center of gravity of the top to rise, the top turning 180° and finally spinning on its stem like an ordinary top. This independently derived analysis shows that the force due to sliding friction is in such a direction as to result in a torque which causes the angular velocity components to vary in a way which necessitates the rising of the center of gravity. This analysis, which emphasizes the physical picture behind the phenomenon, agrees with two previously published papers that friction plays the primary role. Some experimental evidence is given to support the present analysis.

ISSN:0002-9505    

DOI:10.1119/1.1933602

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

A photograph of a very fine contemporary portrait of Joseph Black sculptured in wax by the famous modeler, James Tassie, is here reproduced.

ISSN:0002-9505    

DOI:10.1119/1.1933603

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

In the teaching of the physics connected with the diffraction of x-rays, as well as the daily research practice of taking x-ray diffraction pictures, it is customary to take the pictures on flat x-ray film or upon sheets of film which has been curved into cylinders. In physics teaching this practice has very definite handicaps and appears to be somewhat indirect, because the theoretical treatment of the diffraction of x-rays is more directly connected to the geometry of spheres. We have, therefore, as a teaching aid, coated the inside surface of some hollow glass spheres with photographic emulsion and have recorded upon these spheres the diffraction of x-rays from small crystals located at their centers. Some of the results are shown in Figs. 1 a, b, and c.

ISSN:0002-9505    

DOI:10.1119/1.1933604

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.1933605

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.1933607

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP