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May 2007

Volume 45, Issue 5, pp. 260-320

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Field Quanta in Intro Physics

Elisha Huggins

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 260

Online Publication Date: Apr 2007

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01.40.Fk Research in physics education
01.50.Pa Laboratory experiments and apparatus

Author's Response

Art Hobson

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 260

Online Publication Date: Apr 2007

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01.40.gb Teaching methods and strategies
01.50.Pa Laboratory experiments and apparatus

Defining Work

Carl Mungan

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 261 | Cited 2 times

Online Publication Date: Apr 2007

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01.40.Fk Research in physics education
01.40.J- Teacher training

Physics Saves the Day

Lester Evans

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 261 | Cited 2 times

Online Publication Date: Apr 2007

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Abstract Unavailable
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01.50.My Demonstration experiments and apparatus
01.40.J- Teacher training

Friction and Bouncing Balls

Greg Sherman, Professor of Physics

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 261

Online Publication Date: Apr 2007

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01.50.My Demonstration experiments and apparatus
01.40.J- Teacher training

Author's Response

Robert Beck Clark

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 262

Online Publication Date: Apr 2007

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01.50.My Demonstration experiments and apparatus
01.55.+b General physics
01.40.gb Teaching methods and strategies

Physics Representations in State Standards

Bob Baker

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 262

Online Publication Date: Apr 2007

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01.40.Fk Research in physics education
01.40.J- Teacher training
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To Our Referees: Thank You

Karl C. Mamola

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 264

Online Publication Date: Apr 2007

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Abstract Unavailable
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01.10.Hx Physics organizational activities
01.30.-y Physics literature and publications
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E & M EMISSION

Paul Hewitt

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 266

Online Publication Date: Apr 2007

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01.50.Rt Physics tournaments and contests
01.55.+b General physics
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Flexible Faraday Cage with a Twist: Surface Charge on a Möbius Strip

Seán Stewart

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 268 | Cited 1 time

Online Publication Date: Apr 2007

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Once an intriguing topological novelty known only to mathematicians, the Möbius strip has become a source of fascination and inspiration to the layperson and artist alike.1 Principal among its features are the two strange properties that the Möbius strip is a surface with only one side and one edge. A Möbius strip is readily formed by taking a long rectangular strip of paper and giving one of its ends a half twist before joining it to its other end (see Fig. 1). Given its simplicity, I hoped to profit from its appealing yet counterintuitive nature by designing a simple demonstration experiment that would reveal the intrinsic physical difference between one- and two-sided surfaces.
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01.50.My Demonstration experiments and apparatus
41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems
FREE

Some Interesting Thermodynamics of the Thermos Flask

Roland Berger

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 270

Online Publication Date: Apr 2007

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When opening a thermos flask filled with coffee, one often “hears” the equalization of the pressure difference that appears to be present between the air cavity inside the flask and the surrounding room atmosphere. Recently we discussed this phenomenon while drinking coffee and guessed about the direction of the gas stream accompanying the pressure release. Our hypotheses were tested, and we found that the pressure was higher inside the flask. But this only holds when the coffee is fresh. After some hours one observes an inversion; the pressure inside drops clearly under the environmental value and we wondered—what is going on inside the flask? That question gives the opportunity to discuss some basic thermodynamic concepts, with different degrees of difficulty, in a motivating manner.
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01.50.Pa Laboratory experiments and apparatus
44.00.00 Heat transfer

Torsional Oscillations with Lorentz Force

Paul Gluck

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 274 | Cited 1 time

Online Publication Date: Apr 2007

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We have built a device that uses the Lorentz force on a current-carrying wire situated in a magnetic field, F = I L × B, in order to demonstrate a slowly varying alternating current by means of an optical lever. The apparatus consists of a horseshoe magnet, a length of thin enamel-coated wire (ours was 0.3 mm thick), a signal generator, a rheostat, and a laser. Construction is illustrated in the diagram (Fig. 1).
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01.50.My Demonstration experiments and apparatus
40.00.00 ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS
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Report on the 2006 AAPT Apparatus Competition

Richard Flarend

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 276

Online Publication Date: Apr 2007

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Each year at the AAPT summer meeting there is an apparatus competition in which members of the physics community can share ideas for new or improved apparatus to aid in the teaching of physics. The 2006 competition at the summer meeting in Syracuse, NY, was the largest competition in quite a while and continued an upward trend in the number of entries. Entries ranged in complexity, cost, and target audience, from a $20 apparatus for experimenting with standing waves on the surface of water, to an open design of an atomic force microscope (Fig. 1), which was also relatively low in cost (as far as AFMs go) at around $15,000.
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01.50.My Demonstration experiments and apparatus
01.10.Cr Announcements, news, and awards

Magnetic Levitation and Newton's Third Law

Horacio Munguía Aguilar

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 278 | Cited 2 times

Online Publication Date: Apr 2007

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Newton's third law is often misunderstood by students and even their professors, as has already been pointed out in the literature.1,2 Application of the law in the context of electromagnetism can be especially problematic, because the idea that the forces of “action” and “reaction” are equal and opposite independent of the medium through which they act can be muddied by the concept of “action at a distance.” While some experiments have been described3,4 illustrating Newton's third law in magnetic situations, these do not offer the student a clear way of evaluating his∕her own preconceptions. The experiment we present shows how easily the student, and even the graduate student, can fail to apply the third law correctly in an electromagnetic situation. The experiment described here employs a magnetic levitator and shows the difficulty in recognizing action and reaction forces.
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01.50.My Demonstration experiments and apparatus
01.40.gb Teaching methods and strategies
01.55.+b General physics

An Eight-Parameter Function for Simulating Model Rocket Engine Thrust Curves

Thomas A. Dooling

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 280

Online Publication Date: Apr 2007

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The toy model rocket is used extensively as an example of a realistic physical system. Teachers from grade school to the university level use them. Many teachers and students write computer programs to investigate rocket physics since the problem involves nonlinear functions related to air resistance and mass loss. This paper describes a nonlinear eight-parameter function that correctly models the thrust profile for model rocket engines. Examples are given for commonly used Estes rocket engines.
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02.60.-x Numerical approximation and analysis
45.20.D- Newtonian mechanics
01.50.Wg Physics of toys

Converting Between °C and °F: A Teachable Moment

Lawrence Day

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 285 | Cited 1 time

Online Publication Date: Apr 2007

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Converting between degrees Celsius and degrees Fahrenheit isn't difficult. Remembering when to multiply by 5∕9 or 9∕5 and whether you have to add 32 or subtract 32 makes it fairly easy. Sometimes, though, fairly easy isn't easy enough. Students have trouble remembering the order of operations: “Do I add or subtract 32, and is that before or after I multiply?” Of course, knowing that 32° Fahrenheit is 0° Celsius helps with remembering, but students don't always see it that way. And why is it that you subtract first when going from °F to °C, but multiply first when going the other way?
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06.20.fa Units
01.40.gb Teaching methods and strategies

Thermodynamics of a Block Sliding Across a Frictional Surface

Carl E. Mungan

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 288 | Cited 13 times

Online Publication Date: Apr 2007

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The following idealized problem is intended to illustrate some basic thermodynamic concepts involved in kinetic friction. A block of mass m is sliding on top of a frictional,1 flat-topped table of mass M. The table is magnetically levitated, so that it can move without thermal contact and friction across a horizontal floor. The table is initially stationary, while the block has initial speed vi and slides to rest relative to the table. The block and table are inside a large vacuum tank, so there is no air resistance, buoyancy, nor thermal losses to the atmosphere. Furthermore the inner surface of the vacuum tank is a perfect mirror so that the tank does not radiatively exchange heat with the block and table. The block and table are homogeneous, both initially have temperature Ti, and they each have large thermal conductivities so that they rapidly attain a common final temperature Tf after the block has come to rest. The specific heat capacity of the block is cb and that of the table is ct, and these heat capacities are assumed to be temperature independent over the range of temperatures that arises in this problem. (a) Find the common final speed vf and temperature Tf of the block and table. (b) Find the changes in the bulk kinetic energies K (in the center-of-mass frame of the isolated block-table system), the internal energies U, and the entropies S of the block and table. (c) Discuss the first and second laws of thermodynamics in connection with these results.
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05.70.-a Thermodynamics
45.20.dh Energy conservation
44.90.+c Other topics in heat transfer (restricted to new topics in section 44)

Conductive Critical Thinking

Mark Paetkau

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 292

Online Publication Date: Apr 2007

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One of my goals as an instructor is to teach students critical thinking skills. This paper presents an example of a student-led discussion of heat conduction at the first-year level. Heat loss from a human head is calculated using conduction and radiation models. The results of these plausible (but wrong) models of heat transfer contradict what they know from experience (and from what their mothers have told them). What better way to elicit discussion?
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01.55.+b General physics
44.00.00 Heat transfer

Newton's Apple

Archibald W. Hendry

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 294

Online Publication Date: Apr 2007

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Isaac Newton may have seen an apple fall, but it was Robert Hooke who had a better idea of where it would land. No one really knows whether or not Isaac Newton actually saw an apple fall in his garden. Supposedly it took place in 1666, but it was a tale he told in his old age more than 60 years later, a time when his memory was failing and his recollections of events did not always match known facts. However, one thing is certain—falling objects were to play a key part in Newton's eventual understanding of how objects move.
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01.55.+b General physics
47.00.00 Fluid dynamics

Have You Been to a Good Physics Fight Lately?

Bruce Oldaker

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 299

Online Publication Date: Apr 2007

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The United States Association for Young Physicists Tournaments (USAYPT) held its annual February Tournaments on Feb. 9–10, 2007, at the North Carolina School for Science and Mathematics, Durham, NC. Young physicists' tournaments are theoretical and experimental research-based team competitions described more fully at the USAYPT website: http:∕∕www.usaypt.org.
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01.10.Hx Physics organizational activities
01.50.Rt Physics tournaments and contests

Prepare for Landing

Gregory A. DiLisi and Richard A. Rarick

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 300

Online Publication Date: Apr 2007

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The 2006 Winter Meeting of the AAPT Was Over … and the flight home from Anchorage to Cleveland was just about to end—eight hours in the air, only two complimentary beverages, no meals, a jump across four time zones, a one-year-old baby daughter, and a wife whose motto for the week was, “Why did they choose to have a winter meeting in Alaska?” made for a mentally and physically taxing airborne ordeal. As we entered the last hour of flight, my small family was exhausted and the pilot's decision to dim the interior cabin lights mixed with the soothing hum of the Airbus® A320's engines quickly put us to sleep. Fading in and out of my delirium, I eventually heard the pilot's voice crackle over the intercom with a seemingly innocent comment: “We are going to begin our final descent into Cleveland … we should have you on the ground in exactly eight minutes.” Something about the pilot's use of the word “exactly” must have triggered a reaction in my brain, because his remarks initiated a series of calculations: So how fast are we flying? How high are we flying? What's our angle of descent? With only eight minutes until touchdown, my curiosity to determine the descending airplane's motion led me to conduct a hastily constructed experiment.
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01.55.+b General physics
47.00.00 Fluid dynamics

Debouncing a Superball

Iain MacInnes

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 304 | Cited 3 times

Online Publication Date: Apr 2007

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Superballs can be purchased in local toy stores. They are described as being highly elastic. For bounces on a wooden bench top, the coefficient of restitution, defined as the ratio of the velocity after collision to the velocity before collision, can be determined from the heights reached on successive rebounds. The value obtained is typically about e = 0.8.
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01.55.+b General physics
47.00.00 Fluid dynamics

Graphical Representation of the Doppler Shift: Classical and Relativistic

R. Rojas and G. Fuster

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 306 | Cited 3 times

Online Publication Date: Apr 2007

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The Doppler shift is a frequency change of a repetitive effect, as measured by a receiver, due to the motion of the wave emitter, to the motion of the wave receiver, or both. A demonstration of the effect is provided by the sound of a car's horn that changes from a higher pitch to a lower pitch when a car drives past.1 Most derivations of the Doppler formula assume sinusoidal waves.2–4 We want to call the attention of readers to a derivation that uses a graphical representation based on a graph of position versus time.5 We will adopt a particle model of machine gun bullets fired at a constant period,6–8 thus getting a derivation that just requires the knowledge of kinematics. Furthermore, we will explain how to introduce the time dilation in order to get the formula for the relativistic Doppler shift.
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01.55.+b General physics
01.40.gb Teaching methods and strategies
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An Inexpensive Apparatus for Demonstrating Magnetic Levitation

Carlos Saraiva

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 311 | Cited 2 times

Online Publication Date: Apr 2007

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One way of simulating magnetic levitation is by placing a rotating aluminum disk under a magnet.1 In this article, I will explain how to make an inexpensive apparatus to verify this effect, by recycling an obsolete computer.
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01.50.My Demonstration experiments and apparatus
40.00.00 ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS
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Cell Phones in the Classroom

E. C. Hammond and Meron Assefa

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 312 | Cited 2 times

Online Publication Date: Apr 2007

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Abstract Unavailable
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01.50.My Demonstration experiments and apparatus
01.40.gb Teaching methods and strategies
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Get to the Point … Quicker!

Diane Riendeau

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 313

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01.50.F- Audio and visual aids
01.50.ff Films; electronic video devices
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Every Diamond Has a Silver Lining…

Boris Korsunsky

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 315

Online Publication Date: Apr 2007

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Abstract Unavailable
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01.50.Rt Physics tournaments and contests
01.40.J- Teacher training
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Gender in the Physics Classroom

Laura McCullough

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 316 | Cited 3 times

Online Publication Date: Apr 2007

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Column Editor's note: Laura McCullough teaches physics at the University of Wisconsin—Stout. She has a Ph.D. in science education and conducts physics education research on gender issues in physics. I was impressed with her passion for this issue when I heard her speak at an AAPT session several years ago, and I think you will agree that the insights she shares here can help all of us to ensure equity for all students we teach.
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01.40.Fk Research in physics education
01.40.J- Teacher training
01.75.+m Science and society
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Summer course opportunities for physics teachers

Dan MacIsaac

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 318

Online Publication Date: Apr 2007

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Abstract Unavailable
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01.50.H- Computers in education
01.40.J- Teacher training

More online calculus-based physics video lectures

Dan MacIsaac

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 318

Online Publication Date: Apr 2007

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01.50.ht Instructional computer use
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Fermi Questions

Larry Weinstein

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 319

Online Publication Date: Apr 2007

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Abstract Unavailable
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01.50.Rt Physics tournaments and contests
01.40.J- Teacher training
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MicroReviews by the Book Review Editor: Volta: Science and Culture in the Age of Enlightenment: Giuliano Pancaldi

John L. Hubisz

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 320

Online Publication Date: Apr 2007

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01.30.Vv Book reviews
01.65.+g History of science

MicroReviews by the Book Review Editor: Conflict in the Cosmos: Fred Hoyle's Life in Science: Simon Mitton

John L. Hubisz

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 320

Online Publication Date: Apr 2007

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01.30.Vv Book reviews
01.65.+g History of science

MicroReviews by the Book Review Editor: Blackett: Physics, War, and Politics in the Twentieth Century: Mary Jo Nye

John L. Hubisz

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 320

Online Publication Date: Apr 2007

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01.30.Vv Book reviews
01.65.+g History of science
01.75.+m Science and society

MicroReviews by the Book Review Editor: Pierre Simon Laplace 1749–1827: A Determined Scientist: Roger Hahn

John L. Hubisz

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 320

Online Publication Date: Apr 2007

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01.30.Vv Book reviews
01.65.+g History of science

MicroReviews by the Book Review Editor: Moving the Stars: Christian Doppler, His Life, His Works and Principle, and the World After: Peter Maria Schuster

John L. Hubisz

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 320

Online Publication Date: Apr 2007

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

MicroReviews by the Book Review Editor: Rosalind Franklin and DNA: Anne Sayre

John L. Hubisz

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 320

Online Publication Date: Apr 2007

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Abstract Unavailable
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01.30.Vv Book reviews
01.65.+g History of science

MicroReviews by the Book Review Editor: Rosalind Franklin: The Dark Lady of DNA: Brenda Maddox

John L. Hubisz

The Physics Teacher -- May 2007 -- Volume 45, Issue 5, pp. 320

Online Publication Date: Apr 2007

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