ISSN:0002-9505    

DOI:10.1119/1.18133

出版商:American Association of Physics Teachers    

年代:1996

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.18139

出版商:American Association of Physics Teachers    

年代:1996

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.18206

出版商:American Association of Physics Teachers    

年代:1996

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.18207

出版商:American Association of Physics Teachers    

年代:1996

数据来源: AIP

摘要:

This Resource Letter provides a guide to the literature on causality and determinism in physics. It first surveys the literature of a long history of attempts to construct a systematic account of causality, attempts that constitute options for the use of the concept in physics. It then surveys the status of determinism in classical, relativistic, and quantum theories.

ISSN:0002-9505    

DOI:10.1119/1.18208

出版商:American Association of Physics Teachers    

年代:1996

数据来源: AIP

摘要:

The pumping of a swing from a standing position is modeled as a rigid object forced to rotate back and forth at the lower ends of supporting ropes. This model after some approximations leads to a harmonic oscillator with driving and parametric terms. It is then argued that in the regime of the common playground swing the driving terms dominate and the pumping of a swing in the standing position is best characterized as a driven oscillator. Examination of the relative phase of the swinger and the swing also supports this conclusion. This model is compared with earlier work which claimed that the swing pumped by a standing swinger is characterized as a parametric oscillator. Simple demonstrations of both mechanisms are described. A comparison of pumping while standing and seated is also made.

ISSN:0002-9505    

DOI:10.1119/1.18209

出版商:American Association of Physics Teachers    

年代:1996

数据来源: AIP

摘要:

An odd number of digital not‐gates connected in a closed loop circuit will produce a relatively stable free running oscillator. The frequency of oscillation is determined by the number and type of not‐gates, the circuit supply voltage, and the total length of connection wire used between the not‐gates. Measuring the frequency for various lengths of connection wire enables the speed of the digital signals in the wire to be calculated. The method is sensitive enough to reveal that signals traveling in 22 gauge insulated copper wire propagate about 5% slower than those in 22 gauge bare copper wire. The speed in insulated wire is (2.87±0.03)×108m/s and the speed in bare wire is (3.03±0.02)×108m/s. This experiment has been found to be a very popular undergraduate laboratory due to its low cost, straightforward theory, and relatively high (∼1%) precision. The absence of a light source eliminates complicated optics and impresses students with the fact that visible light is not theonlything that travels with the speed of light!

ISSN:0002-9505    

DOI:10.1119/1.18355

出版商:American Association of Physics Teachers    

年代:1996

数据来源: AIP

摘要:

One reason why Brownian motion and Johnson noise are difficult subjects to teach is that their mathematical requirements transcend the capabilities of ordinary differential calculus. Presented here is an exposition of the needed generalization of calculus, namely continuous Markov process theory, in a form that should be accessible to advanced physics undergraduates. It is shown how this mathematical framework enables one to give clear, concise derivations of all the principal results of Brownian motion and Johnson noise, including fluctuation–dissipation formulas, auto‐covariance transport formulas, spectral density formulas, Nyquist’s formula, the notions of white and 1/f2noise, and an accurate numerical simulation algorithm. An added benefit of this exposition is a clearer view of the mathematical connection between the two very different approaches to Brownian motion taken by Einstein and Langevin in their pioneering papers of 1905 and 1908.

ISSN:0002-9505    

DOI:10.1119/1.18210

出版商:American Association of Physics Teachers    

年代:1996

数据来源: AIP

摘要:

A photon counting experiment for student physics laboratory is described. It is designed to illustrate the probabilistic nature of the photodetection process itself as well as statistical fluctuations of light. The setup enables the student to measure photon count distributions for both coherent and pseudothermal light sources yielding Poisson and Bose–Einstein distributions, respectively.

ISSN:0002-9505    

DOI:10.1119/1.18211

出版商:American Association of Physics Teachers    

年代:1996

数据来源: AIP

摘要:

Students first meet the wave‐particle paradox through the photon and wave descriptions of light. Yet, in basic courses on quantum mechanics, they study matter particles only, because the mathematics of the quantized radiation field is usually considered too advanced. An oscillating electromagnetic field is formally similar to a harmonic oscillator, whose energy eigenstates can represent states of well‐defined photon number. Using a computer program from the CUPS project, an approach will be described which demonstrates the action of the annihilation operator on these states, constructs coherent states which behave like classical electromagnetic fields, and shows how such states can be squeezed. All of these have practical relevance in modern optics. This is just one example of the computer making a hitherto unapproachable subject accessible to ordinary undergraduates. Computers have already changed how much of quantum mechanics is taught. As more such possibilities are realized, the teaching of the whole subject must surely change radically.

ISSN:0002-9505    

DOI:10.1119/1.18212

出版商:American Association of Physics Teachers    

年代:1996

数据来源: AIP