摘要:

Most geometric representations of the Lorentz transformation use either imaginary angles or imaginary space-time coordinates. A new and simple representation is proposed using only real coordinates and real angles, and allowing a graphical illustration of the major features of the Lorentz transformation.

ISSN:0002-9505    

DOI:10.1119/1.1934074

出版商:American Association of Physics Teachers    

年代:1955

数据来源: AIP

摘要:

(1) Walking is related closely to a succession of motions approximating half-cycles of a simple harmonic motion. The large velocities and accelerations involved are computed. (2) The support of the body on the ball of one foot, as in walking, introduces large forces in bones and muscles which are analyzed. (3) A simple experiment related to standing on tiptoe is described.

ISSN:0002-9505    

DOI:10.1119/1.1934075

出版商:American Association of Physics Teachers    

年代:1955

数据来源: AIP

摘要:

The two-fluid barometer, invented by Descartes and constructed by Huygens, has been undeservedly neglected. It combines almost the compactness of the mercury barometer with almost the sensitiveness of the water barometer. Two patterns, the straight-tube and the J-tube, are described in this paper. Reasons for preferring the J-tube pattern are given. Neither pattern requires more than routine glassblowing skill. The two fluids may be mercury and butyl phthalate. Instructions for filling the barometer are included. The finished instrument is a good teaching piece and is interesting to the general public, but it is not recommended as a replacement for the standard mercury barometer when highly accurate readings are needed.

ISSN:0002-9505    

DOI:10.1119/1.1934076

出版商:American Association of Physics Teachers    

年代:1955

数据来源: AIP

摘要:

In each decade prophets predict the maximum frequency which triode oscillators may ever attain. In each decade the limit is revised upward by a factor of two. The present upper limit for commercial triodes is about 6000 Mc/sec (5-cm wavelength). For each demonstration in physical optics there is a most convenient wavelength. Waves of 12 cm are most convenient for classroom demonstrations of the Fresnel diffraction. For the Fraunhofer and Bragg diffraction 5-cm waves are better. A microwave spectrometer for 5-cm waves is described.

ISSN:0002-9505    

DOI:10.1119/1.1934077

出版商:American Association of Physics Teachers    

年代:1955

数据来源: AIP

摘要:

An experiment is described wherein the resistance of a galvanometer is measured by several different methods. A number of difficulties arise in this experiment, which are analyzed. It is shown how these difficulties can be used to give the student important lessons about good experimentation.

ISSN:0002-9505    

DOI:10.1119/1.1934078

出版商:American Association of Physics Teachers    

年代:1955

数据来源: AIP

摘要:

A method of producing Chladni figures by continuous excitation is described. Thin metallic plates are placed in the sound field of a 15-watt (or higher) loud-speaker driven by an audio-oscillator and power-amplifier combination. Advantages of this method, especially for demonstration purposes, are enumerated.

ISSN:0002-9505    

DOI:10.1119/1.1934080

出版商:American Association of Physics Teachers    

年代:1955

数据来源: AIP

摘要:

An interesting anomaly in the familiar Kundt tube experiment and the eighty-year search for an interpretation is reviewed for teachers of physics. Unfortunately the correct explanation of this phenomenon, although available, is rarely cited and known to very few. The work and explanation of Andrade are presented and expanded in hopes of remedying this situation.

ISSN:0002-9505    

DOI:10.1119/1.1934081

出版商:American Association of Physics Teachers    

年代:1955

数据来源: AIP

摘要:

It is demonstrated by a general argument, using the property of isotropic intensity characteristic of cavity radiation, that the emissive radiance from the surface of a blackbody is Lambertian.

ISSN:0002-9505    

DOI:10.1119/1.1934082

出版商:American Association of Physics Teachers    

年代:1955

数据来源: AIP

摘要:

This paper describes a simple bent mica x-ray spectrograph that was built for use in a senior course in atomic physics. The theory and construction of the spectrograph are discussed and its application to the study of the properties of x-rays by means of the recording of direct and fluorescent radiations is described.

ISSN:0002-9505    

DOI:10.1119/1.1934083

出版商:American Association of Physics Teachers    

年代:1955

数据来源: AIP

摘要:

A lecture demonstration is described, which allows verification of the relativistic relation between kinetic energy and momentum,(mc2+E)2 = m2c4+c2p2. Electrons are accelerated by a small high-voltage generator (van de Graaff, of approximately 250 kv) and deflected in a magnetic field of approximately 100 gauss. The measured values of high-voltage and deflecting magnetic field are plotted on a straight line which represents the relation given above.

ISSN:0002-9505    

DOI:10.1119/1.1934084

出版商:American Association of Physics Teachers    

年代:1955

数据来源: AIP