摘要:

This article reviews the recent discovery and several important applications of recoilless gamma-ray fluorescence. Its main purpose is to give to nonspecialists a self-contained introduction to this currently very lively field of research. The importance of the fluorescence technique and its limitations, before Mössbauer's discovery, are discussed. Mössbauer's pioneering experiments are briefly described and Lipkin's simple theoretical explanation of recoilless gamma-ray emission is presented. From among the large number of recent experiments which make use of the Mössbauer effect, two groups are selected for discussion. The first is concerned with the discovery of nuclear and magnetic properties of iron-57; the other with a test of the principle of equivalence in general relativity, by a measurement of the gravitational shift in the frequency of radiation.

ISSN:0002-9505    

DOI:10.1119/1.1937662

出版商:American Association of Physics Teachers    

年代:1961

数据来源: AIP

摘要:

Six definitions of resonance are distinguished and considered for the seriesLCRcircuit. The corresponding exact conditions are derived for each of the four variables and their practical significance discussed. Some of the results for the parallelLCRcircuit are briefly considered.

ISSN:0002-9505    

DOI:10.1119/1.1937661

出版商:American Association of Physics Teachers    

年代:1961

数据来源: AIP

摘要:

Gauge transformations are treated from the point of view of unitary transformations in ordinary quantum mechanics. Gauge-independent form of the constants of the motion is discussed. It is shown that the orbital angular momentum in an arbitrary gauge is given byr×[(p−eA)+12e(B×r)].

ISSN:0002-9505    

DOI:10.1119/1.1937663

出版商:American Association of Physics Teachers    

年代:1961

数据来源: AIP

摘要:

A simple apparatus for an undergraduate laboratory measurement of the ratioe/mof electrons by Classen's method is described. A flanged metal vacuum chamber contains the electrode system, a filament, two adjustable slits, and a collector. Helmholtz coils supplying the magnetic field are mounted externally. Accelerating potentials of 750 to 1500 v and fields of 60 to 70 gauss are required. The electrode system can be conveniently removed from the chamber for inspection and measurement. When properly adjusted, the apparatus will permit the determination of the ratioe/mto a precision of ±2%.

ISSN:0002-9505    

DOI:10.1119/1.1937664

出版商:American Association of Physics Teachers    

年代:1961

数据来源: AIP

摘要:

A small electromagnet designed for use with an indium-antimonide Hall effect device is described. A coil current of 2.3 amp produces a field of 3 kgauss across a 0.56-cm gap. The field is uniform to within 10% over an area1.5×1.5 cm. Fields high enough for use with a germanium sample are practical.

ISSN:0002-9505    

DOI:10.1119/1.1937665

出版商:American Association of Physics Teachers    

年代:1961

数据来源: AIP

摘要:

It is shown that the fact that a local Galilean frame of reference or a local instrument such as the gyrocompass preserves its orientation with respect to the universe of stars is adequately explained by the fact that the universe of stars has the unique property of having no detectable mechanical interaction with local bodies. The Mach principle asserts that the universe of stars has some connection with local mechanical phenomena. The considerations of this note suggest that the universe of stars appears to have some connection with local phenomena for the paradoxical reason that it has no connection.

ISSN:0002-9505    

DOI:10.1119/1.1937666

出版商:American Association of Physics Teachers    

年代:1961

数据来源: AIP

摘要:

A theory of the effect of a circular metal disk in screening the electric field of a pole and the magnetic field of a radio-frequency dipole (eddy current screening) on the axis is developed in terms of spheroidal functions. The screening effectiveness is defined as the ratio of the screened to the unscreened field and curves are given showing its variation along the disk axis. In the electrical case the field is zero at a certain distance along the axis.

ISSN:0002-9505    

DOI:10.1119/1.1937667

出版商:American Association of Physics Teachers    

年代:1961

数据来源: AIP

摘要:

It is shown that Buchdahl's treatment involves a tacit extension of Carathéodory's second axiom, that if such extension be made the zeroth law becomes a consequence of the other basic assumptions, and that Buchdahl's parameters, the empirical entropy for a system, is the same asx0, the nondeformation coordinate of a simple system related to the system in question.

ISSN:0002-9505    

DOI:10.1119/1.1937668

出版商:American Association of Physics Teachers    

年代:1961

数据来源: AIP

摘要:

A wave function which represents a decaying exponential in all space is shown to be the limiting solution to a one-dimensional square well potential problem. If the limit is defined properly, the expectation value of the kinetic energy is shown to be positive definite.

ISSN:0002-9505    

DOI:10.1119/1.1937669

出版商:American Association of Physics Teachers    

年代:1961

数据来源: AIP

摘要:

By relying on the complete similarity of an accelerated coordinate system with a gravitational field, a simple accelerated loop-the-loop is described, by which a ball starting at the bottom rolls backward up over a loop and is caught at the top. Simple means of accelerating the apparatus suffice.

ISSN:0002-9505    

DOI:10.1119/1.1937670

出版商:American Association of Physics Teachers    

年代:1961

数据来源: AIP