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Sep 2007

Volume 75, Issue 9, pp. 773-864

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COMMENT ON “SCHOOL MATH BOOKS, NONSENSE, AND THE NATIONAL SCIENCE FOUNDATION,” BY DAVID KLEIN [AM. J. PHYS. 75 (2), 101–102 (2007)]

Leslie J. Atkins

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 773

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01.40.-d Education

COMMENT ON “SCHOOL MATH BOOKS, NONSENSE, AND THE NATIONAL SCIENCE FOUNDATION,” BY DAVID KLEIN [AM. J. PHYS. 75 (2), 101–102 (2007)]

Terry Millar

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 775

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01.40.-d Education

REPLY TO COMMENTS ON “SCHOOL MATH BOOKS, NONSENSE, AND THE NATIONAL SCIENCE FOUNDATION,” BY DAVID KLEIN [AM. J. PHYS. 75 (2), 101–102 (2007)]

David Klein

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 776

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01.40.-d Education

EARTH ROTATION VIA DOPPLER SHIFTS?

Geoffrey E. Stedman

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 778

Online Publication Date: Aug 2007

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42.00.00 Optics

AUTHOR’S REPLY

Luis Bernal and Luis Bilbao

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 778

Online Publication Date: Aug 2007

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42.00.00 Optics
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One Short Year

A. John Mallinckrodt

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 779 | Cited 1 time

Online Publication Date: Aug 2007

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01.10.-m Announcements, news, and organizational activities
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Teaching theoretical physics: The cases of Enrico Fermi and Ettore Majorana

Alberto De Gregorio and Salvatore Esposito

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 781 | Cited 3 times

Online Publication Date: Aug 2007

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We report on theoretical courses by Enrico Fermi and Ettore Majorana, which give evidence of the first appearance and further development of quantum mechanics teaching in Italy. On the basis of original documents, we compare Fermi and Majorana’s approaches. A detailed analysis is made of Fermi’s course on theoretical physics attended by Majorana in 1927–28. Three (previously unknown) programs on advanced physics courses submitted by Majorana to the University of Rome between 1933 and 1936 and the course he taught in Naples in 1938 complete our analysis. Fermi’s phenomenological approach resounded in Majorana, who combined it with a deeper theoretical approach, closer to the contemporary way of presenting quantum mechanics.
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01.65.+g History of science

Real Time Relativity: Exploratory learning of special relativity

C. M. Savage, A. Searle, and L. McCalman

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 791 | Cited 6 times

Online Publication Date: Aug 2007

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“Real Time Relativity” is a computer program that lets users move at relativistic speeds through a simulated world populated with planets, clocks, and buildings. The counterintuitive and spectacular optical effects of relativity are prominent, while systematic exploration of the simulation allows the user to discover relativistic effects such as length contraction and the relativity of simultaneity. We report on the physics and technology underpinning the simulation, and our experience using it for teaching special relativity to first year students.
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03.30.+p Special relativity
01.50.ht Instructional computer use

Using ordinary multiplication to do relativistic velocity addition

Alma Teao Wilson

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 799

Online Publication Date: Aug 2007

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Although a mainstay of undergraduate courses on relativity, relativistic velocity addition is usually a pedagogical dead-end that yields little insight. We propose instead the use of velocity factors (two-way Doppler factors). Velocities can easily be converted to velocity factors, and vice versa. Velocity factors compose by ordinary multiplication. This simplification places interesting problems within reach at the introductory level. It also provides a springboard for subsequent treatment of rapidities, Bondi’s k-calculus, null or lightlike coordinates, and even spinorial formulations of relativity.
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03.30.+p Special relativity

How do two moving clocks fall out of sync? A tale of trucks, threads, and twins

Daniel F. Styer

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 805 | Cited 5 times

Online Publication Date: Aug 2007

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In special relativity, a pair of clocks synchronized in their own reference frame are not synchronized in another. How do two clocks, initially synchronized and at rest in the laboratory frame, fall out of sync as their speed relative to the lab gradually increases? The answer lies in general-relativistic time dilation. The path to the answer sheds light on the thread-between-spaceships paradox (also called the Bell spaceship paradox), on the twin paradox, and on the character of length contraction.
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03.30.+p Special relativity

Irreversible transfer processes of thermoelectric generators

Min Chen, Lasse Rosendahl, Inger Bach, Thomas Condra, and John Pedersen

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 815 | Cited 6 times

Online Publication Date: Aug 2007

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We discuss a novel tool based on heat flow diagrams for analyzing irreversible processes associated with thermoelectric devices and discuss some ambiguous descriptions and errors in related investigations. We consider thermoelectric generators as a paradigm of a heat engine cycle and determine the heat flow distribution by treating the one-dimensional heat transfer differential equation. Representative heat flow diagrams are used to study the influence of internal and external irreversible processes of heat conduction and Joule heat generation.
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05.00.00 Statistical physics, thermodynamics, and nonlinear dynamical systems

Optical response of two-electron atoms: A classical formulation

Wei Guo

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 821 | Cited 1 time

Online Publication Date: Aug 2007

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When the dielectric constant of a medium formed by many-electron atoms is studied in classical physics, the electron-electron interaction within each atom is often ignored. To examine the conditions for which this approximation is valid, we consider a simplified classical model in which each atom contains two electrons interacting with each other through the Coulomb potential. It is found that the dielectric constant becomes approximately independent of the electron-electron interaction only when the electrons have the same damping constant and binding frequency.
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41.00.00 Electromagnetism; electron and ion optics
42.00.00 Optics

Verification of the Rayleigh scattering cross section

Sayan Chakraborti

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 824 | Cited 4 times

Online Publication Date: Aug 2007

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A simple experiment is described for the direct determination of the wavelength dependence of the Rayleigh scattering cross section using the classic example of the blue sky. Suggestions for inclusion into an undergraduate lab are discussed.
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50.00.00 PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

Optical diffraction microscopy in a teaching laboratory

Pierre Thibault and Ivan C. Rankenburg

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 827 | Cited 4 times

Online Publication Date: Aug 2007

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We discuss an optics experiment that reproduces all important aspects of diffraction microscopy or coherent diffractive imaging. This technique is used to reconstruct an object’s image from its diffraction pattern. The experimental setup is described in detail and only requires material readily available in a well-equipped optics teaching laboratory. The data analysis procedure is explained, in particular the reconstruction part, for which an iterative phase retrieval algorithm is used. The method is illustrated by showing the complex-valued reconstruction of an insect wing from a diffraction pattern measured with this setup.
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01.50.Pa Laboratory experiments and apparatus
42.00.00 Optics

Velocity field measurements in a rectangular conduit with particle image velocimetry

Román Martino, Agnes Paterson, and Marcelo F. Piva

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 833 | Cited 2 times

Online Publication Date: Aug 2007

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We present a simple experimental setup to study the velocity profile in a rectangular closed conduit. Particle image velocimetry was applied to obtain the velocity profiles for several values of aspect ratios and for different flow rates. The velocity profile is obtained in the central longitudinal plane of the conduit and in the downstream region where the flow is fully developed. Close agreement between experimental results and theoretical predictions is found.
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01.50.Pa Laboratory experiments and apparatus
47.00.00 Fluid dynamics

An electrochromic film device to teach polymer electrochemical physics

Mei-Rong Huang, Tao Tao, Xin-Gui Li, and Qian-Cheng Gong

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 839 | Cited 7 times

Online Publication Date: Aug 2007

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We discuss the background associated with an electrochromic device that can reversibly change its color and optical density at a specific potential. We discuss the underlying science needed to make a new polyaniline (PAN)/polyvinyl alcohol(PVA) electrochromic composite film on an indium-tin oxide (ITO) conducting glass by electropolymerization and describe a reversible redox transition of the PAN. The experiment gives students an opportunity to fabricate an electrochromic device containing PAN, one of the most important conducting polymers. The experimental conditions are flexible so that each group of students can construct their own electrochromic device with particular behavior. Two techniques for polymerizing the PAN and three methods of demonstrating the electrochromism are given, depending on the available apparatus. A sophisticated three-electrode potentiostat or a crude apparatus containing a battery, wire, a variable resistor, and a voltage meter is used to synthesize the PAN deposit. The electrochromic property is repetitively observed by reversibly changing the applied potentials on the device. A potentiostatic apparatus, a single flashlight battery, or a flashlight battery accompanied by a variable resistor allows students to observe multicolor electrochromism. The experiments significantly enhance students’ understanding of polymer chemicophysics principles and their appreciation of novel variable colorful films. The experiments are safe and easy to perform, provided that appropriate precautions are taken.
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01.50.Pa Laboratory experiments and apparatus
82.00.00 Physical chemistry and chemical physics
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Comment on “Preacceleration without radiation: The nonexistence of preradiation phenomenon,” by J. A. Heras [Am. J. Phys. 74 (11), 1025–1030 (2006)]

J. D. Jackson

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 844 | Cited 3 times

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41.00.00 Electromagnetism; electron and ion optics

Comment on “Preacceleration without radiation: The nonexistence of preradiation phenomenon,” by J. A. Heras [Am. J. Phys. 74 (11), 1025–1030 (2006)]

V. Hnizdo

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 845 | Cited 1 time

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41.00.00 Electromagnetism; electron and ion optics

Reply to “Comment(s) on ‘Preacceleration without radiation: The nonexistence of preradiation phenomenon,’” by J. D. Jackson [Am. J. Phys. 75 (9), 844–845 (2007)] and V. Hnizdo [Am. J. Phys. 75 (9), 845–846 (2007)]

José A. Heras

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 847

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41.00.00 Electromagnetism; electron and ion optics

Comment on “On Mach’s critique of Newton and Copernicus,” by Herbert I. Hartman and Charles Nissim-Sabat [Am. J. Phys. 71 (11), 1163–1169 (2003)]

A. Bhadra and S. C. Das

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 850 | Cited 2 times

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Hartman and Nissim-Sabat have argued that Mach’s idea of the relativity of rotational motion suffers from internal inconsistencies and leads to a contradiction that there cannot be a stationary bucket in a rotating universe. They also claimed that non-inertial electromagnetic and stellar aberration observations can distinguish between a rotating and a stationary universe, whereas according to Mach there cannot be any observable way to distinguish these two cases. We contest these objections.
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01.70.+w Philosophy of science
03.30.+p Special relativity

Reply in Light of Contemporary Physics to “Comment on ‘On Mach’s critique of Newton and Copernicus,”' by Herbert I. Hartman and Charles Nissim-Sabat [Am. J. Phys. 71 (11), 1163–1169 (2003)]

Herbert I. Hartman and Charles Nissim-Sabat

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 854 | Cited 2 times

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Mach argued for a relational rather than an absolute notion of space, insisting that centrifugal forces inside a rotating object such as a bucket can be reproduced by keeping the bucket fixed and rotating the universe. In a recent paper, Bhadra and Das elaborate on Mach’s position. We show that Mach’s relational notion of space is incomplete. Also, special and general relativity distinguish between a bucket rotating in a fixed universe and a bucket fixed in a rotating universe and between a nonrotating bucket in a nonrotating universe and a co-rotating bucket in a rotating universe, distinctions that go against Mach’s relational theory of space.
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01.70.+w Philosophy of science
03.30.+p Special relativity
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An improved demonstration of charge conservation

Wolfgang Rueckner

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 861

Online Publication Date: Aug 2007

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Abstract Unavailable
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01.50.My Demonstration experiments and apparatus
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BOOKS RECEIVED

American Journal of Physics -- September 2007 -- Volume 75, Issue 9, pp. 864

Online Publication Date: Aug 2007

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Abstract Unavailable
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