ISSN:0002-9505    

DOI:10.1119/1.12443

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.12446

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.4755855

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

It is argued that the temperature concept has a richer theoretical basis than is generally appreciated. The importance of an absolute comparative concept of temperature is emphasized. A set of necessary and sufficient conditions for the existence and metricization of the temperature quantity is examined. It is shown that these conditions are all consequences of the laws of thermodynamics together with a number of ancillary thermodynamic assumptions. The absolute comparative concept of temperature as well as the absolute scale are introduced without employing the concept of a thermometer. The general notion of a thermometer is introduced as an addendum to thermodynamics.

ISSN:0002-9505    

DOI:10.1119/1.12448

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

Simultaneous production of two pure tones with frequenciesf1andf2is associated both with auditory beats (rapid fluctuations in loudness) and with audible difference tones. Since the same frequencyf1−f2is encountered in both cases, students tend to think a difference tone is nothing more than a beat phenomenon whose frequency is high enough to be in the audible range. But, in fact, these are two entirely distinct effects. This article discusses how to convincingly present this difference at three levels: (1) simple theory of added and multiplied waveforms; (2) visual demonstration with electronic Fourier analyzer; and (3) audible demonstration. These show that our ears can literally hear and distinguish two separate phenomena.

ISSN:0002-9505    

DOI:10.1119/1.12449

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

The problem of calculating the precession of the equinoxes due to the torque of the sun and moon on the Earth is often cited in mechanics texts as a classic example of the behavior of a heavy symmetrical top. Unfortunately this problem is often alluded to but seldom solved. A simple equatorial band model for the Earth and smeared out mass distributions for the sun and moon are used herein to solve this problem. It is found that one intuitively apparent approximation for the gravitational force on the band results in a precession period that is too long by a factor of 3/2, whereas a slightly more sophisticated approach provides an answer good to better than one percent.

ISSN:0002-9505    

DOI:10.1119/1.12450

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

Elementary optical considerations are used to show how depth of field, exposure correction, and Scheimpflug focusing are obtained for a view camera. Although designed primarily for photography majors taking a ’’physics of photography’’ course, the material discussed could form the basis of an optics laboratory experiment for physics majors.

ISSN:0002-9505    

DOI:10.1119/1.12451

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

The quantum‐mechanical properties of electron spin are developed systematically from a nonrelativistic Hamiltonian. The correct values of the magnetic moment of the electron, the spin‐orbit coupling energy of atomic electrons, the Darwin correction, and the angular momentum of the electron are obtained directly without explicitly including any relativity beyond classical electromagnetism.

ISSN:0002-9505    

DOI:10.1119/1.12452

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

The study of the quantum bouncer in a closed court is used to illustrate some concepts and techniques of quantum mechanics at different levels.

ISSN:0002-9505    

DOI:10.1119/1.12453

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

A plastic lens is described which will bend light rays parallel to the lens axis in the same way as a static (Schwarzschild) gravitational field. This allows one to observe the optical distortions caused by a (nonrotating) black hole directly. The double‐imaging property is discussed with particular application to the recently announced double quasar which is suspected to be a gravitational double image of a single quasar. A detailed cosmological model calculation is performed in order to place limits on the mass of the galaxy acting as the lens. It is seen that if the double quasar is a double image and if the lens is a massive galaxy then we will have established that the quasar redshift is cosmological rather than gravitational. The gravitational lens thus occupies a key role in resolving this question.

ISSN:0002-9505    

DOI:10.1119/1.12440

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP