摘要:

A simple electromechanical analog for Landau’s classical theory of second‐order symmetry‐breaking transitions is presented. The apparatus consists of a torsion pendulum, where a ceramic magnet suspended by two torsion springs is subjected to a uniform magnetic field. The pendulum angle is the analog of the order parameter in a phase transition, while the current passing through the Helmholtz coil, which produces the magnetic field, plays the role of temperature. With this setup, the critical exponents β, δ, γ, and γ’can be determined with good accuracy.

ISSN:0002-9505    

DOI:10.1119/1.16427

出版商:American Association of Physics Teachers    

年代:1990

数据来源: AIP

摘要:

The scattering of laser light by a glass fiber is easy to observe experimentally, though the scattering pattern will usually be rather complex. By applying the partial wave method familiar from quantum mechanical scattering, it is possible to calculate the pattern exactly.

ISSN:0002-9505    

DOI:10.1119/1.16428

出版商:American Association of Physics Teachers    

年代:1990

数据来源: AIP

摘要:

By treating scalar diffraction as a Fourier transform problem, it is possible to calculate the expected intensity patterns for arbitrary apertures using standard signal‐processing software on a personal computer. This article presents a series of experiments on optical diffraction and spatial filtering phenomena, and quantitatively compares the results with calculations. Both the experimental and calculational methods are suitable for an advanced undergraduate laboratory.

ISSN:0002-9505    

DOI:10.1119/1.16429

出版商:American Association of Physics Teachers    

年代:1990

数据来源: AIP

摘要:

This article describes the construction and operation of a totally enclosed motion room capable of carrying four students. The room is used for studying motion in a rotating frame. The rotation rate can be varied from 0 to above 20 rpm. Unique features of this motion room are the 60‐in. searchlight frame used for the mount and electrical connections and the two cattle watering troughs used for the motion room proper. The room, built a number of years ago, has not previously been described in the literature.

ISSN:0002-9505    

DOI:10.1119/1.16398

出版商:American Association of Physics Teachers    

年代:1990

数据来源: AIP

摘要:

Einstein’s opposition to the quantum theory is well known to physicists, but his reasons for being dissatisfied are not. Einstein regarded the theory as not only incomplete, but as fundamentally inadequate. He believed that the only reasonable interpretation of the quantum formalism was an ‘‘ensemble interpretation,’’ but he also thought that this interpretation and others were incomplete and irremediably inadequate, because they failed to describe the objective, real states of individual systems. He hoped, and expected, that a better theory would be developed—one expressed in terms of individuals having their own real states and from which the quantum theory could be recovered as an approximation.

ISSN:0002-9505    

DOI:10.1119/1.16399

出版商:American Association of Physics Teachers    

年代:1990

数据来源: AIP

摘要:

Realism and locality are defined emphasizing the fundamental character of both principles. From this, the well‐known expression proposed by Bell for calculating correlations is derived. Starting from this expression, the theorem of incompatibility is proved between local realism and quantum mechanics. An analysis is made of the experiments performed by Aspect and others, and it is concluded that, because photomultipliers and polarizing filters are not perfectly efficient, it is necessary to make subsidiary assumptions about how they operate in order to rule out local realism. It is argued that the subsidiary assumptions are not logically necessary and, consequently, local realism has not yet been refuted empirically.

ISSN:0002-9505    

DOI:10.1119/1.16400

出版商:American Association of Physics Teachers    

年代:1990

数据来源: AIP

摘要:

Instead of taking the usual geometrical approach, the phenomenon of light bending is treated as a quantum scattering problem. This treatment is instructive and straightforward considered when the gravitational field is weak, and can be easily applied even for massive particles, as is demonstrated with the example of a massive spinless particle.

ISSN:0002-9505    

DOI:10.1119/1.16403

出版商:American Association of Physics Teachers    

年代:1990

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.16404

出版商:American Association of Physics Teachers    

年代:1990

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.16405

出版商:American Association of Physics Teachers    

年代:1990

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.16406

出版商:American Association of Physics Teachers    

年代:1990

数据来源: AIP