ISSN:0002-9505    

DOI:10.1119/1.13622

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.13890

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.13891

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.4755912

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.4755913

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

Several different conceptualizations of entropy are examined: thermal, probabilistic, quantum‐mechanical, information theoretic, black‐hole, and chaotic. The unifying nature of entropy in all physical processes and recent cosmological advances are discussed.

ISSN:0002-9505    

DOI:10.1119/1.13892

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

In order to prove the general validity of the second law of thermodynamics, several instances of the Stirling cycle are studied, especially in relation to their efficiency.

ISSN:0002-9505    

DOI:10.1119/1.13893

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

Elementary numerical methods of integrating an equation of motion are systematically compared, both theoretically and experimentally. It is shown that the half‐step approximation and the closely related second‐order Taylor approximation are far superior to the other elementary methods, in particular, the various Euler approximations. The idea of a variable stepping interval is discussed and is shown to be highly advantageous when used with the second Taylor approximation.

ISSN:0002-9505    

DOI:10.1119/1.13894

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

The interaction of α particles with low atomic number elements has been studied in an attempt to determine the inner‐shell ionization cross section. These cross sections were determined by measuring the characteristic x rays that were produced when a thin aluminum target was bombarded by α particles from a 48‐MBq224Cm α source. The x rays were detected with a Si(Li) x‐ray detector whose resolution was 190 eV at 5.9 keV. The efficiency of the detector was determined from standard radioactive sources. The energies of the α particles were varied by placing thin Mylar absorbers between the α source and the target. The results are favorably compared to a current ionization theory given in such a form that an undergraduate physics major can do the calculations. This experiment is intended as an undergraduate laboratory experiment in the atomic or nuclear area.

ISSN:0002-9505    

DOI:10.1119/1.13870

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

Normal matrices are the largest class of matrices which can be diagonalized by unitary transformations. They include Hermitian, anti‐Hermitian, unitary, real symmetric, and real orthogonal matrices, the primary types of interest to physicists. An aesthetically and practically satisfying synthesis as well as a significant saving of effort is achieved by studying normal matrices first and then deducing results for the various particular types subsequently. A simple constructive proof of the fundamental result that every normal matrix can be diagonalized by a unitary matrix is given.

ISSN:0002-9505    

DOI:10.1119/1.13860

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP