摘要:

The early 18th‐century observatories constructed in five North Indian cities by the Raja Jai Singh represent the last historical attempt to carry out a major program in observational astronomy using naked eye methods alone. The major instruments are described and the precision of each is estimated. An attempt is then made to discern the motives which led Jai Singh to construct these observatories more than a century after Galileo first used the telescope for astronomical purposes. It is concluded that Jai Singh’s astronomical program can only be understood in terms of the place which science occupied in the social and political matrix of late Moghul India.

ISSN:0002-9505    

DOI:10.1119/1.10033

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

We have for several years offered a course entitled ’’Energy and the Environment’’ that is quantitative where necessary, is aimed at the general student, and surveys systematically the whole energy problem and its social, political, economic, and moral implications. The course is perhaps unique in combining all these characteristics with the use of outside experts whose contributions are closely integrated with the thread of the course as a whole.

ISSN:0002-9505    

DOI:10.1119/1.10034

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

The most general motion of an isolated thermodynamic system K in equilibrium is determined by Landau and Lifshitz through an appeal to the equilibrium condition δS=0. It is argued that this work actually amounts to a demonstration of the internal consistency of the thermodynamic formalism in this case since the problem is soluble by an appeal to prior criteria. We use these to determine all motions consistent with equilibrium in the more general case of a system K which is not isolated. Although the temperature would of necessity be uniform if K were at rest, this is no longer obviously the case when it is moving. To emphasize this point, we first determine the possible relativistic motions of K, restricted to be translations in a fixed direction, and then determine explicitly the distribution of absolute temperature within it. It turns out to be nonuniform only when K is accelerated, and then it varies in a manner consistent with the principle of equivalence.

ISSN:0002-9505    

DOI:10.1119/1.10035

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

A procedure for constructing a Runge vector for a particle moving (classically or relativistically) under any central force has been given by Fradkin. Serebrennikov and Shabad have pointed out that such vectors may be piecewise conserved, rather than constants for the entire motion. It is shown herein that, for the classical isotropic harmonic oscillator, the above procedure can lead to a piecewise‐conserved Runge vector as well as to a conserved one (of the same magnitude). We relate this ambiguity to the symmetries of the orbit.

ISSN:0002-9505    

DOI:10.1119/1.10036

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

A recently instituted Physics Learning Center is described and evaluated. Innovations in the use of the facility include self‐paced student observation of phenomena, ’’PLC homework problems,’’ and extracurricular use by off‐campus groups.

ISSN:0002-9505    

DOI:10.1119/1.9958

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

A method is described by which a multiple‐slit interference pattern can be demonstrated quite easily with the help of an inexpensive Fabry–Perot etalon and a low‐power laser beam. The separation between the ’’slits’’ can be adjusted continuously. The experiment brings forth the similarity between a grating and a Fabry–Perot as a fringe‐sharpening device. A simple derivation of the analytical expression for such fringes is presented.

ISSN:0002-9505    

DOI:10.1119/1.9959

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

A Fabry–Perot etalon is used to display both the longitudinal and the transverse modes present in a laser beam. Analysis and experimentations show that plates no better than λ/20 flatness and spacers in the range between 4 and 10 cm are satisfactory for helium–neon lasers.

ISSN:0002-9505    

DOI:10.1119/1.9960

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

In the present article we discuss several volume and surface integral expressions for an electromagnetic field in the presence of a scatterer of finite extension, with special emphasis on a description of the scattering by means of a transition matrix.

ISSN:0002-9505    

DOI:10.1119/1.9961

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

The data from a projects laboratory experiment are analyzed to give values of the coefficient of thermal conductivity λ. Experiments using simplified apparatus were carried out on the temperature and pressure dependence. Thermal conductivity of gas measurements are discussed for the case of large gradients in coaxial cylinder apparatus, a technique used in recent research. The various sources of error common to such measurements are assessed, including convection according to recent treatments.

ISSN:0002-9505    

DOI:10.1119/1.9962

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

A circuit is described that enables one to use simple equipment to improve the precision with which the frequency of a driven mechanical vibrator can be measured. The resonance frequency of the system consisting of a mass suspended from a spring is calculated by a procedure that simplifies the application of the general equation which is valid for all masses.

ISSN:0002-9505    

DOI:10.1119/1.9963

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP