ISSN:0002-9505    

DOI:10.1119/1.9854

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

A steel ball bounces in synchronism with a vertically oscillating piston. The piston surface is a hardened steel disk on which the ball bounces; two−dimensional horizontal focusing is provided by the concavity of the surface. The period of oscillation can be varied over a 3:1 range with the amplitude kept constant. As the period is increased, the ball bounces higher. As the period is decreased, the ball bounces lower, contrary to the intuition of most observers. The model illustrates the important properties of synchrotron accelerators.

ISSN:0002-9505    

DOI:10.1119/1.9855

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

A simple experimental configuation is described for recording good quality 360° holograms with a minimum of effort and expense. The reconstructed images allow one to observe in three dimensions how an original object appears from all sides save top and bottom.

ISSN:0002-9505    

DOI:10.1119/1.9856

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

This paper presents several cases in which the effects of the addition of a delta function potential on bound states can be computed exactly. In the case of the one dimensional Schrödinger equation, a Green’s function technique is used to compute an exact implicit expression that gives the effect of the one−dimensional delta function potential on the bound states eigenvalues. It is also shown that the weak coupling limit of the implicit expression agrees with the perturbative treatment of the delta function. It is pointed out that this technique cannot be applied to obtain an exact treatment of the delta function potential δ3(r) in the three−dimensional Schrödinger equation. Instead, an alternate definition of the delta function in three dimensions as a limit of a sequence of square well potentials is used. Unlike the one dimensional case, the exact effect on the eigenvalue does not agree in the limit of weak coupling with the perturbative results. This indicates that the three−dimensional delta function potential should not be used to approximate strongly coupled short range potentials for which perturbation theory is inadequate.

ISSN:0002-9505    

DOI:10.1119/1.9857

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

An experiment suitable for an advanced undergraduate laboratory is described in which the free−electron cyclotron resonance of electrons trapped in a microwave cavity by a Penning trap is observed. The systematic errors appear to be less than in the Gardner and Purcell cyclotron resonance experiment, amounting to not more than 20 ppm, probably less. The resonance peak can be located with a precision of 5 ppm with modest equipment. Since the microwave cavity is easy to construct, the experiment constitutes an attractive alternative to one of the Gardner−Purcell variety.

ISSN:0002-9505    

DOI:10.1119/1.9858

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

An n−dimensional Debye model is analyzed and solved obtaining the phonon density of states, the phonon energy and the lattice specific heat, thus providing a unified approach to the teaching of this model. Cases with n=1, 2, and 3 are explicitly considered.

ISSN:0002-9505    

DOI:10.1119/1.9859

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

The Physics Department at East Carolina recently instituted two separate programs at the freshman level in an attempt to attract more students into its classes and to improve the students’ attitude toward physics. One program involved a multimedia format in a course for science majors, and the other involved a new sequence of courses for nonscience majors. Due mainly to faculty resistance, the multimedia format was discontinued in the fall quarter of 1973. However, the enrollment in the nonscience major sequence has been increasing rapidly, and a noticeable change in the students’ attitude toward physicists has been effected.

ISSN:0002-9505    

DOI:10.1119/1.9860

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

An elementary proof of Bell’s theorem on the incompatibility of local hidden−variable theories with quantum mechanics is presented. The proof is based on considerations of error rates in binary message sequences.

ISSN:0002-9505    

DOI:10.1119/1.9861

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

Statistical moments of the relativistic Maxwell−Boltzmann momentum distribution are obtained from integral representations of modified Bessel functions. Approximate low temperature (m/kT≫1) behaviors for the mean and mean−square momenta are indicated via asymptotic expansions of corresponding Bessel functions and the results are briefly contrasted with the usual classical predictions. The most probable momentum is also discussed.

ISSN:0002-9505    

DOI:10.1119/1.10079

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

It is shown that the conventional correspondence procedure used in the transition from Newtonian to the Einsteinian theory of gravitation is not unique. A new procedure of correspondence whereby the theory is required to reduce to a special relativistic limit before it reduces to the Newtonian limit is described. It is shown that the special relativistic correspondence leads to first and second order requirements, whereas the Newtonian correspondence leads only to first order requirements. The resulting theory is logically plausible and experimentally viable.

ISSN:0002-9505    

DOI:10.1119/1.10080

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP