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Apr 2007

Volume 75, Issue 4, pp. 293-384

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BUILDING A TRANSMISSION ELECTRON MICROSCOPE

Tung Hsu

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 293

Online Publication Date: Mar 2007

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Abstract Unavailable
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01.50.My Demonstration experiments and apparatus

ADVANCED LABS SUPPORT BY AAPT

Harvey S. Leff

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 293

Online Publication Date: Mar 2007

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Abstract Unavailable
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01.10.-m Announcements, news, and organizational activities
01.50.Pa Laboratory experiments and apparatus
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Resource Letter PSEn-1: Physics and society: Energy

Art Hobson

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 294

Online Publication Date: Mar 2007

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This Resource Letter provides a guide to the physics-related literature about energy-and-society. Journal articles, books, and websites are cited for the following topics: general references, textbooks, other pedagogical resources, population growth, fossil fuels, global warming, nuclear power, side effects of nuclear power, fusion power, renewable resources (including hydroelectric, biofuels, wind, photovoltaics, direct solar, geothermal, hydrogen, and energy storage), energy efficiency, and transportation efficiency.
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01.30.Rr Surveys and tutorial papers; resource letters
01.75.+m Science and society
89.30.-g Fossil fuels and nuclear power

Automating data acquisition for the Cavendish balance to improve the measurement of G

Noah Fitch, Wesley Bliven, and Tyler Mitchell

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 309 | Cited 1 time

Online Publication Date: Mar 2007

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The Leybold-Heraeus gravitational torsion balance is commonly used in undergraduate laboratories to measure the gravitational attraction between known masses to find the gravitational constant G. Because the difficult task of data acquisition reduces its usefulness, we have implemented a simple design that minimizes this task and achieves more accurate results. This design features a small car that tracks the oscillating laser with the use of a stepper motor and some simple control circuitry. Step counting yields the location of the reflected laser in time.
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01.50.Pa Laboratory experiments and apparatus

Experiments on subtractive color mixing with a spectrophotometer

P. U. P. A Gilbert and Willy Haeberli

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 313 | Cited 3 times

Online Publication Date: Mar 2007

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We describe experiments on color mixing suitable for undergraduate nonscience majors. A commercial spectrophotometer is used to study the spectra of light sources, combinations of color filters, and mixtures of acrylic paints. Special emphasis is placed on teaching the fundamentals of subtractive color mixing and the complex processes that occur in mixing pigments.
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01.50.Pa Laboratory experiments and apparatus
42.00.00 Optics

Does nature convert mass into energy?

Ralph Baierlein

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 320 | Cited 3 times

Online Publication Date: Mar 2007

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First I provide some history of how the equation E=mc2 arose, establish what “mass” means in the context of this relation, and present some aspects of how the relation can be understood. Then I address the question, Does E=mc2 mean that one can “convert mass into energy” and vice versa?
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01.65.+g History of science
03.30.+p Special relativity

Nonlinear damping of the LC circuit using antiparallel diodes

Edward H. Hellen and Matthew J. Lanctot

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 326

Online Publication Date: Mar 2007

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We investigate a simple variation of the series RLC circuit in which antiparallel diodes replace the resistor. The result is a damped harmonic oscillator with a nonlinear damping term that is a maximum at zero current and decreases inversely with the current for currents far from zero. Unlike the standard RLC circuit, the behavior of this circuit is amplitude dependent. The transient response makes a transition from underdamped to overdamped behavior, and the resonance response of the steady-state driven oscillator becomes sharper as the source amplitude increases. A set of nonlinear differential equations is derived for the circuit and integrated numerically for comparison with measurements. The equipment is inexpensive and common to upper level physics labs.
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01.50.Pa Laboratory experiments and apparatus
84.30.-r Electronic circuits

Round an expanding world: A simple model to illustrate the kinematical effects of the cosmological expansion

C. Criado and N. Alamo

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 331 | Cited 1 time

Online Publication Date: Mar 2007

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We use a rubber balloon model to give a simple explanation of the motion of photons and galaxies in an expanding and collapsing universe. In particular, we study the Friedmann-Lemaitre-Robertson-Walker closed universe. The behavior of the peculiar velocity of galaxies in an expanding universe is also studied with the help of this model.
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04.00.00 General relativity and gravitation

Linearized Kerr and spinning massive bodies: An electrodynamics analogy

J. Franklin and P. T. Baker

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 336 | Cited 2 times

Online Publication Date: Mar 2007

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We discuss the correspondence between spinning, charged spherical sources in electrodynamics and spinning, massive spherical sources in linearized general relativity and show that the form of the potentials and equations of motion are similar in the two cases in the slow motion limit. This similarity allows us to interpret the Kerr metric in analogy with a spinning sphere in electrodynamics and aids in understanding linearized general relativity, where the “forces” are effective and come from the intrinsic curvature of space-time.
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04.00.00 General relativity and gravitation

Ghost imaging: Open secrets and puzzles for undergraduates

Lorenzo Basano and Pasquale Ottonello

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 343

Online Publication Date: Mar 2007

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Ghost imaging, a novel technique in which the object and the image system are on separate optical paths, was first demonstrated using entangled photon pairs. This demonstration caused it to be regarded as a purely quantum effect, but subsequent work gave wide support to a classical explanation. We provide an introduction to ghost imaging based more on intuition than on formalism and discuss several experiments that can be implemented in a university physics laboratory.
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42.00.00 Optics

The first-order orbital equation

Maurizio M. D’Eliseo

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 352 | Cited 6 times

Online Publication Date: Mar 2007

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We derive the first-order orbital equation employing a complex variable formalism. We then examine Newton’s theorem on precessing orbits and apply it to the perihelion shift of an elliptic orbit in general relativity. It is found that corrections to the inverse-square gravitational force law formally similar to that required by general relativity were suggested by Clairaut in the 18th century.
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04.00.00 General relativity and gravitation

Why the near field radiation from a large distributed source is independent of position

Duane R. Doty, Henry J. Scudder, III, Ravi R. Gupta, and Carlos Y. Saa

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 356

Online Publication Date: Mar 2007

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Background radiation from terrestrial sources of uranium, thorium, and potassium complicate the counting of radiation from a weak source. Although radiation from a localized point source decreases as the inverse square of the distance from the source, moving a counter further from a concrete table or floor does not decrease the background. Measurements of the intensity of radiation versus height above a local surface were made and found not to vary with height. A simple model is proposed assuming a uniform volume distribution with self-absorption as a source. It is shown that most of the radiation comes from relatively close surroundings.
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20.00.00 NUCLEAR PHYSICS

Making a fluid rotate: Circular flow of a weakly conducting fluid induced by a Lorentz body force

Rafael M. Digilov

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 361 | Cited 2 times

Online Publication Date: Mar 2007

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We describe the magnetohydrodynamic (MHD) flow of a viscous, electrically conducting, and incompressible fluid driven by the Lorentz body force inside the annulus between two stationary coaxial cylindrical electrodes under imposed electric and magnetic fields. The azimuthal velocity profile is found for axisymmetrical, fully developed laminar and steady flow at arbitrary annulus curvature and different values of the Hartmann number Ha. It is shown that for Ha⩽1, the MHD annular flow behaves as a conventional hydrodynamic fluid driven by an azimuthal Lorentz body force.
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47.00.00 Fluid dynamics

Superlinearly convergent homogeneous maps and period of the pendulum

S. Siboni

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 368 | Cited 1 time

Online Publication Date: Mar 2007

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The period of a pendulum can be accurately determined by an arithmetic-geometric map. The high efficiency of the map is due to superlinear convergence, which can be understood from a geometrical point of view by writing the map as a skew system (or master-slave system) whose master component has a globally asymptotically stable fixed point with order of convergence two, which reduces the behavior of the map to a one-dimensional dynamics. It is shown that the map shares many features with a general class of maps of the real plane.
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02.00.00 Mathematical methods in physics

Giving bonus points based on oral exams

Robert Ehrlich

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 374

Online Publication Date: Mar 2007

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A pedagogical experiment of giving bonus points based on oral exams in an introductory physics course is described. The orals covered the questions on a written exam that had just been graded and returned to the class. Although the performance of most students on the oral exams was fair at best, the value of bonus point orals would appear to be considerable, even though it may not be applicable to large classes and have other important disadvantages.
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01.40.-d Education
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Comment on “Development and assessment of research-based tutorials on heat engines and the second law of thermodynamics,” by Matthew J. Cochran and Paula R. L. Heron [Am. J. Phys. 74 (8), 734–741 (2006)]

Manfred Bucher

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 377

Online Publication Date: Mar 2007

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Abstract Unavailable
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05.70.-a Thermodynamics

Automated heat capacity apparatus on a circuit board

Jeffrey Clayhold and Joseph Priest

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 379 | Cited 2 times

Online Publication Date: Mar 2007

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Abstract Unavailable
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01.50.Pa Laboratory experiments and apparatus
05.70.-a Thermodynamics
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The Cosmic Landscape: String Theory and the Illusion of Intelligent Design.

Leonard Susskind, Editor and Michael Dine, Reviewer, Reviewer

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 382

Online Publication Date: Mar 2007

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Abstract Unavailable
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01.30.Vv Book reviews
10.00.00 THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

A Love of Discovery: Science Education—The Second Career of Robert Karplus.

Robert G. Fuller and Juan R. Burciaga, Reviewer, Reviewer

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 383

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Abstract Unavailable
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01.30.Vv Book reviews
01.60.+q Biographies, tributes, personal notes, and obituaries
01.40.-d Education

BOOKS RECEIVED

American Journal of Physics -- April 2007 -- Volume 75, Issue 4, pp. 384

Online Publication Date: Mar 2007

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Abstract Unavailable
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