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Jun 2007

Volume 75, Issue 6, pp. 485-576

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A FINITE LINE OF CHARGE

Gerald L. Pollack and Daniel R. Stump

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 485

Online Publication Date: May 2007

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Abstract Unavailable
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41.00.00 Electromagnetism; electron and ion optics

VIDEO MOTION TRACKING

Nathan Kimball

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 486

Online Publication Date: May 2007

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Abstract Unavailable
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01.50.Pa Laboratory experiments and apparatus
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Editorial changes in AJP

Jan Tobochnik

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 487 | Cited 1 time

Online Publication Date: May 2007

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Abstract Unavailable
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01.10.-m Announcements, news, and organizational activities
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Raman scattering spectroscopy of liquid nitrogen molecules: An advanced undergraduate physics laboratory experiment

B. L. Sands, M. J. Welsh, S. Kin, R. Marhatta, J. D. Hinkle, and S. B. Bayram

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 488 | Cited 5 times

Online Publication Date: May 2007

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We describe a straightforward and highly visual experiment designed to demonstrate Raman scattering spectroscopy by measuring the vibrational energy spacing of nitrogen molecules in the liquid phase. Interpretation of the spectrum teaches the principles of elastic and inelastic light scattering and the intrinsic properties of molecules. The use of a pulsed Nd:YAG laser with high peak power leads to a plethora of nonlinear optical phenomena. The presence of highly visible stimulated Raman scattering greatly enhances the normal Raman-shifted signal, allowing for a more engaging laboratory experience in comparison to traditional Raman scattering experiments.
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01.50.Pa Laboratory experiments and apparatus

A lesson in the physics laboratory on the superheating of water

Concetto Gianino

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 496

Online Publication Date: May 2007

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The theory of water vaporization is used to understand the phenomenon of boiling and the mechanisms of bubble formation. A simple experiment was done to verify the theory and measure the bubble radius under superheating conditions. Experimental results are in good agreement with calculated values.
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01.50.Pa Laboratory experiments and apparatus
05.70.-a Thermodynamics

An experiment on the Rayleigh instability of charged liquid drops

Chee Sheng Fong, Nathan D. Black, Peter A. Kiefer, and Raymond A. Shaw

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 499 | Cited 2 times

Online Publication Date: May 2007

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We describe a simple experiment to observe the fission of an electrically charged liquid droplet. Rayleigh charge instability occurs when the electrostatic repulsion of charges on the surface of a droplet overcomes the droplet surface tension and tears the droplet apart. The experiment requires a low-power laser, simple optics, a CCD camera, and a quadrupole trap, which can be constructed using widely available and relatively straightforward instructions. The experiment was performed primarily by undergraduates as part of their senior research projects and can be implemented readily in an advanced undergraduate physics laboratory course.
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01.50.Pa Laboratory experiments and apparatus
47.00.00 Fluid dynamics

Quantum mechanical versus semiclassical tunneling and decay times

Mark R. A. Shegelski, Jeremy Kavka, and Jeff Hnybida

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 504 | Cited 3 times

Online Publication Date: May 2007

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We present a method for calculating lifetimes without using semiclassical approximations by using a heuristic expression for the lifetime. The details are given for tunneling past a centrifugal barrier. We compare the fully quantum mechanical results to the well-known WKB tunneling times. We show that bound states play a major role in determining lifetimes.
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03.65.-w Quantum mechanics

Two variational variations on a problem in electrostatics

Anupam Garg

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 509

Online Publication Date: May 2007

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Two nonstandard variational approximations are developed for a problem in electrostatics. The results are compared with a numerical solution based on the relaxation method. Suggestions for further study are made.
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41.00.00 Electromagnetism; electron and ion optics

Discrepancy between published Laplace difference equations on cylindrical dielectrics

Fabrizio Pinto

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 513 | Cited 4 times

Online Publication Date: May 2007

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The problem of two unequal electrodes within a shielding cavity in the presence of a dielectric partially filling the gap is treated by means of overrelaxation methods in the axisymmetric case. A discrepancy in the literature concerning the boundary equation between two dielectrics is resolved and the difference equation for the dielectric corner point is obtained by means of Gauss’ law. Some numerical results are described.
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41.00.00 Electromagnetism; electron and ion optics

Elementary simulation of tethered Brownian motion

John F. Beausang, Chiara Zurla, Laura Finzi, Luke Sullivan, and Philip C. Nelson

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 520 | Cited 3 times

Online Publication Date: May 2007

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We describe a simple simulation, suitable for an undergraduate project or graduate problem set, of the Brownian motion of a particle in a Hooke’s law potential well. Understanding this physical situation is necessary in many experimental contexts, for instance in single molecule biophysics, and its simulation helps students appreciate the dynamical character of thermal equilibrium. The simulation captures behavior seen in experimental data on tethered particle motion.
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05.00.00 Statistical physics, thermodynamics, and nonlinear dynamical systems
87.00.00 Biological and medical physics

Critical dipoles in one, two, and three dimensions

Kevin Connolly and David J. Griffiths

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 524 | Cited 10 times

Online Publication Date: May 2007

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The Schrödinger equation for a point charge in the field of a stationary electric dipole admits bound states only when the dipole moment exceeds a certain critical value. It is not hard to see why this might be the case, but it is surprisingly difficult to calculate the critical dipole moment. The analogous problem should be simpler in one and two dimensions, but a general theorem forbids critical moments in one dimension, and explicit calculation shows that there is no critical moment in two dimensions.
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03.65.-w Quantum mechanics

The electric dipole moment of the electron: An intuitive explanation for the evasion of Schiff’s theorem

Eugene D. Commins, J. D. Jackson, and David P. DeMille

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 532 | Cited 4 times

Online Publication Date: May 2007

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In most experimental searches for the electron electric dipole moment, one searches for a linear Stark effect in a paramagnetic atom or molecule and interprets the result in terms of the electric dipole moment of the unpaired valence electron(s). Schiff’s theorem states that in the limit of nonrelativistic quantum mechanics, there can be no linear Stark effect to first order in the electric dipole moment. Sandars has shown that Schiff’s theorem is not applicable when special relativity is taken into account. We give a heuristic explanation for this relativistic effect, which corrects a widespread misconception in the literature.
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03.65.-w Quantum mechanics

Second Born approximation and Coulomb scattering

Barry R. Holstein

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 537 | Cited 1 time

Online Publication Date: May 2007

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We examine the problem of calculating higher order contributions to the Coulomb scattering amplitude. To make contact with the well known result, it is necessary to modify the conventional definition of the scattering amplitude.
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03.65.-w Quantum mechanics

Visualizing flat spacetime: Viewing optical versus special relativistic effects

Don V. Black, M. Gopi, Frank Wessel, Renato Pajarola, and Falko Kuester

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 540

Online Publication Date: May 2007

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A visual representation of Minkowski spacetime appropriate for a student with a background in geometry and algebra is presented. Minkowski spacetime can be modeled with a Euclidean four-space to yield accurate visualizations as predicted by special relativity. The contributions of relativistic aberration as compared to classical prerelativistic aberration to the geometry are discussed in the context of its visual representation.
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03.30.+p Special relativity

Introduction to modes and their designation in circular and elliptical fibers

Deepak Kumar and P. K. Choudhury

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 546 | Cited 1 time

Online Publication Date: May 2007

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Some basic ideas are presented to clarify the concept of modes in optical fibers. We describe the formation of modes and the indexing schemes in circular and elliptical core fibers.
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42.00.00 Optics

Berry’s phase through the path integral formulation

M. A. Alves and M. T. Thomaz

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 552

Online Publication Date: May 2007

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We study the evolution of a quantum system under adiabatic conditions using the path integral formulation. We obtain the Berry phase for systems with nondegenerate and degenerate energy spectra and recover well-known results. We also present a simple derivation of the adiabatic theorem.
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03.65.-w Quantum mechanics

On an identity for the volume integral of the square of a vector field

A. M. Stewart

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 561 | Cited 4 times

Online Publication Date: May 2007

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A proof is given of the vector identity proposed by Gubarev, Stodolsky, and Zakarov that relates the volume integral of the square of a three-vector field to nonlocal integrals of the curl and divergence of the field. The identity is applied to the vector potential and magnetic field of a rotating charged shell. The latter provides a straightforward application of the use of the addition theorem of spherical harmonics.
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41.00.00 Electromagnetism; electron and ion optics

On the nonradiative and quasistatic conditions and the limitations of circuit theory

Alfonso Zozaya

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 565

Online Publication Date: May 2007

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Field theory is used to analyze a simple circuit and to deduce the conditions for nonradiative and quasistatic fields. From the condition for quasistatic fields, which is the more stringent of the two, Kirchhoff’s voltage equation and its range of validity are deduced. These conditions for the validity of circuit theory are not treated appropriately in the undergraduate curricula. A simple numerical problem is given to illustrate these ideas.
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41.00.00 Electromagnetism; electron and ion optics
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Comment on “On an identity for the volume integral of the square of a vector field,” by A. M. Stewart [Am. J. Phys. 75 (6), 561–564 (2007)]

Loyal Durand

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 570 | Cited 1 time

Online Publication Date: May 2007

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Abstract Unavailable
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41.00.00 Electromagnetism; electron and ion optics
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A classroom experiment to measure the speed-dependent coefficient of rolling friction

Y. Xu, K. L. Yung, and S. M. Ko

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 571 | Cited 2 times

Online Publication Date: May 2007

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To help students understand one of the most basic mechanical phenomena, rolling friction, a simple laboratory setup for measuring the rotational speed-dependent coefficient of rolling friction was developed. Equipment and apparatus used in the measurement are simple and easy to acquire, yet the phenomena and the mechanisms behind it are intriguing. The air drag force, which is caused by air friction, is used in the measurement to reduce the cost of the apparatus.
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01.50.Pa Laboratory experiments and apparatus
47.00.00 Fluid dynamics
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La Dame d'Esprit: A Biography of the Marquise De Châtelet.

Judith P. Zinsser and Hans Christian von Baeyer, Reviewer

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 575

Online Publication Date: May 2007

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Abstract Unavailable
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01.30.Vv Book reviews
01.60.+q Biographies, tributes, personal notes, and obituaries
01.65.+g History of science

Passionate Minds: The great love affair of the Enlightenment, featuring the scientist Emilie du Châtelet, the poet Voltaire, sword fights, book burnings, assorted kings, seditious verse, and the birth of the modern world.

David Bodanis and Hans Christian von Baeyer, Reviewer

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 575

Online Publication Date: May 2007

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Abstract Unavailable
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01.30.Vv Book reviews
01.60.+q Biographies, tributes, personal notes, and obituaries
01.65.+g History of science

BOOKS RECEIVED

American Journal of Physics -- June 2007 -- Volume 75, Issue 6, pp. 576

Online Publication Date: May 2007

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Abstract Unavailable
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