ISSN:0002-9505    

DOI:10.1119/1.17954

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

How can educators assess and address the lack of interest exhibited by underrepresented youth in science? What strategies can be employed to recruit and retain these young people? Along with a bibliography, the author provides the reader with a brief summary of 20 notable works in the field of recruitment and retention of underrepresented students in math and science. Although highlighted retention and intervention programs reported herein are targeted at young women in particular, many of the suggested strategies are applicable to all students regardless of race, gender, or socio‐economic background. It provides scientists who have an interest in science education with basic literature addressing this topic.

ISSN:0002-9505    

DOI:10.1119/1.17955

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

The principles of optics are used in examining the claims of an unusual bowl sundial whose inscription taunts us with an ability to recreate a miracle of the Old Testament, that of reversing time. Ray tracing is first employed as a tool to allow restoration of the instrument to its original condition so that the sun’s shadow moves backwards. A mathematical model is developed to test this phenomena on different dates and at a variety of locations. Directions are given to easily demonstrate this phenomena in the classroom.

ISSN:0002-9505    

DOI:10.1119/1.17956

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

Apparent paradoxes associated with Feynman’s picture of plane wave radiation arising from a uniform sheet of surface charge which is suddenly placed into motion are pointed out and resolved.

ISSN:0002-9505    

DOI:10.1119/1.17957

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

We investigate the physics of an interstellar journey on board a spaceship with a constant acceleration, in the framework of special relativity. It is in principle possible to cross the Galaxy within a human lifetime. The aspect of the sky seen from the spaceship is severely distorted by relativistic aberration; most of the visible sky shrinks to a small region of strongly enhanced luminance in the direction of motion, leaving the rest of the celestial sphere almost entirely dark. The invisible universe becomes perceptible by the traveler, as the infrared and radio radiations are Doppler‐shifted to visible frequencies in the direction of motion. Navigational problems posed by these relativistic effects are examined.

ISSN:0002-9505    

DOI:10.1119/1.17958

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

We describe the behavior of a unipolar generator that is an obvious variant of the Faraday disk. The behavior of our device, if properly interpreted, is in agreement with the principle of relativity. ‘‘For nearly a century after its discovery by Faraday in 1832 the unipolar generator was a conundrum for the theory of electromagnetism.’’—D. F. Bartlettetal. Phys. Rev. D16(12), 3459–3463 (1977).

ISSN:0002-9505    

DOI:10.1119/1.17928

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

The most efficient way to operate a rocket is to increase its exhaust velocity as it accelerates. When this increase is done properly, the final kinetic energy of the rocket is maximized. It is shown that the resulting ‘‘perfect rocket’’ is far simpler to analyze than the traditional constant‐thrust rocket and provides an excellent application of the material taught in all first semester noncalculus physics courses.

ISSN:0002-9505    

DOI:10.1119/1.17929

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

A heavy duty hacksaw blade and a 1000 turn pick‐up coil form the basis of a mechanical oscillator for a laboratory exercise in mechanical resonance designed for either the elementary course or in association with an upper level mechanics course. Damped harmonic motion, amplitude, and phase resonance curves, and the transient motion of the system can be studied. Since the resonant frequencies are in the 10 to 20 Hz range, a digital multimeter can be used to record accurate amplitude resonance curves with minimal tedium.

ISSN:0002-9505    

DOI:10.1119/1.17930

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

The aim of this paper is to provide a simple illustration of how the thermodynamic analysis of equilibrium states may be generalized to nonequilibrium steady states characterized by a nonvanishing heat flow. To achieve this aim, we use maximum‐entropy arguments to describe a relativistic ideal gas under the constraints on the mean values of the internal energy and the heat flow. The partition function, the entropy, and the pressure tensor are obtained in terms of the internal energy, volume, number of particles, and heat flow. In the limit of vanishing heat flow, we recover the usual equilibrium thermodynamics. Thus our analysis exhibits in an explicit way some of the most relevant modifications of the thermodynamic quantities in presence of the heat flow.

ISSN:0002-9505    

DOI:10.1119/1.17931

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP

摘要:

In this paper we demonstrate how a duality transformation allows us to derive the Liénard–Wiechert fields of a particle possessing both electric and magnetic charge (i.e., the so‐called dual‐charged particle) in terms of the well‐known Liénard–Wiechert fields of the electric charge. By making use of this result, we derive also theLarmorformula for a nonrelativistic, accelerated dual‐charged particle.

ISSN:0002-9505    

DOI:10.1119/1.17932

出版商:American Association of Physics Teachers    

年代:1995

数据来源: AIP