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Mar 2011

Volume 49, Issue 3, pp. 132-192

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Reaching the peaks of teaching

Iain Macinnes

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 132

Online Publication Date: Feb 2011

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01.40.Ha Learning theory and science teaching
01.40.ek Secondary school
01.40.gb Teaching methods and strategies
01.50.Kw Techniques of testing

Quarks

Babak Makkinejad

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 132

Online Publication Date: Feb 2011

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01.50.-i Educational aids
01.40.-d Education

Downwash and lift force in helicopter flight

John C. Strong

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 132

Online Publication Date: Feb 2011

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01.50.-i Educational aids
01.40.-d Education

Distinguishing mass and weight

Gordon Aubrecht

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 133

Online Publication Date: Feb 2011

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01.40.Di Course design and evaluation
01.50.F- Audio and visual aids
01.50.Kw Techniques of testing
14.65.-q Quarks
14.70.Dj Gluons
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SOUND FROM A TRAIN

Paul Hewitt

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 134

Online Publication Date: Feb 2011

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01.50.fh Posters, cartoons, art, etc.
43.00.00 Acoustics
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Teaching Elementary Particle Physics, Part II

Art Hobson

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 136 | Cited 1 time

Online Publication Date: Feb 2011

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In order to explain certain features of radioactive beta decay, Wolfgang Pauli suggested in 1930 that the nucleus emitted, in addition to a beta particle, another particle of an entirely new type. The hypothesized particle, dubbed the neutrino, would not be discovered experimentally for another 25 years. It's not easy to detect neutrinos, because they respond to neither the EM force nor the strong force. For example, the mean free path (average penetration distance before it interacts) of a typical beta‐decay neutrino moving through solid lead is about 1.5 light years!1 Enrico Fermi argued that neutrinos indicated a new force was at work. During the 1930s, he quickly adapted ideas from the developing new theory of QED to this new force, dubbed the weak force. Fermi's theory was able to predict the half‐lives of beta‐emitting nuclei and the range of energies of the emitted beta particles.
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01.40.G- Curricula and evaluation
12.15.-y Electroweak interactions
12.20.Ds Specific calculations
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How Rosalind Franklin Discovered the Helical Structure of DNA: Experiments in Diffraction

Gregory Braun, Dennis Tierney, and Heidrun Schmitzer

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 140 | Cited 1 time

Online Publication Date: Feb 2011

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Rosalind Franklin, a chemical physicist (1920–1958), used x‐ray diffraction to determine the structure of DNA. What exactly could she read out from her x‐ray pattern, shown in Fig. 1?1 In lecture notes dated November 1951, R. Franklin wrote the following: “The results suggest a helical structure (which must be very closely packed) containing 2, 3 or 4 co‐axial nucleic acid chains per helical unit, and having the phosphate groups near the outside.”2 This was 16 months before J. D. Watson and F. Crick published their description of DNA, which was based on R. Franklin's x‐ray photos. How they gained access to her x‐ray photos is a fascinating tale of clashing personalities and male chauvinism.2,3
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01.50.Pa Laboratory experiments and apparatus

Deformation of Water by a Magnetic Field

Zijun Chen and E. Dan Dahlberg

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 144

Online Publication Date: Feb 2011

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After the discovery that superconducting magnets could levitate diamagnetic objects,1,2 researchers became interested in measuring the repulsion of diamagnetic fluids in strong magnetic fields,3–5 which was given the name “The Moses Effect.”5 Both for the levitation experiments and the quantitative studies on liquids, the large magnetic fields necessary were produced by superconducting magnets.
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62.10.+s Mechanical properties of liquids

Special Relativity in Week One: 1) The Principle of Relativity

Elisha Huggins

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 148 | Cited 3 times

Online Publication Date: Feb 2011

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We like to begin an introductory physics course with a law of physics that applies to everything, has no known exceptions, and whose consequences are already familiar to students. That law is the principle of relativity. By focusing on the principle of relativity itself, and a careful selection of the thought experiments, we can comfortably introduce the basic concepts of special relativity that we will use later in the course.1 This allows us to construct an introductory physics course that includes 20th‐ and 21st‐century physics as we go along, rather than shoving modern physics off the back end.2
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01.50.Pa Laboratory experiments and apparatus

An Experimental Investigation of the End Effects for Blue Man Group® Pipes

M. E. Bacon and Steven Torok

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 152

Online Publication Date: Feb 2011

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One of us (ST) constructed a Blue Man Group® instrument1 from 2‐in PVC piping2 (internal radius r = 2.54 cm) as an undergraduate project. The instrument itself is shown in Fig. 1.
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01.50.Pa Laboratory experiments and apparatus

Large General Purpose Frame for Studying Force Vectors

Christy Heid and Donald Rampolla

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 156

Online Publication Date: Feb 2011

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Many illustrations and problems on the vector nature of forces have weights and forces in a vertical plane. One of the common devices for studying the vector nature of forces is a horizontal “force table,”1 in which forces are produced by weights hanging vertically and transmitted to cords in a horizontal plane. Because some students have difficulty relating the geometry of the textbook illustrations with weights in a vertical plane to the horizontal geometry of a force table, we developed a vertical force frame, shown in Figs. 1 and 2, that allows a vertical arrangement of weights and cords that mimics exactly the textbook illustrations, and is on a scale that makes it easy for the students to “feel” the magnitudes of forces. This frame is easy to build, inexpensive, and provides a working area of almost 5 ft × 5 ft (1.8 m × 1.8 m) and a number of alternative ways of working with forces. This frame can also be easily expanded to an area of 10 ft × 5 ft (3.6 m × 1.8 m) for large complex configurations. The frame is easy to assemble or disassemble using only a VSR drill and deck screws, and stores compactly. Students can gain engineering skills by assembling the frame guided by schematic drawings.
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01.50.Pa Laboratory experiments and apparatus
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Collaborative Lab Reports with Google Docs

Michael Wood

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 158

Online Publication Date: Feb 2011

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Science is a collaborative endeavor. The solitary genius working on the next great scientific breakthrough is a myth not seen much today. Instead, most physicists have worked in a group at one point in their careers, whether as a graduate student, faculty member, staff scientist, or industrial researcher. As an experimental nuclear physicist with research at the Thomas Jefferson National Accelerator Facility, my collaboration consists of over 200 scientists, both national and international. A typical experiment will have a dozen or so principal investigators. Add in the hundreds of staff scientists, engineers, and technicians, and it is clear that science is truly a collaborative effort. This paper will describe the use of Google Docs for collaborative reports for an introductory physics laboratory.
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01.50.Qb Laboratory course design, organization, and evaluation
01.40.gf Theory of testing and techniques

The Area of a Circle

Thomas B. Greenslade, Jr.

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 160 | Cited 1 time

Online Publication Date: Feb 2011

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The geometrical shapes in Fig. 1 recently came into the Greenslade Collection. The semi‐triangular pieces of wood looked like slices from a pie, each 22.5° in angular width. They were tied together with a thin leather band tacked around their curved surfaces. What is this apparatus?
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01.50.Pa Laboratory experiments and apparatus

Automatic Flushing Toilets: An Entertaining Platform for Exploring Scientific Thinking

Brian S. Blais

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 162

Online Publication Date: Feb 2011

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It is often challenging, especially at the beginning of a course, to find good examples where students can actively explore and grapple with the methods of science. We want them to learn the connection between observation, theory, prediction, evidence, and falsification, but to really accomplish this we need platforms for which the students are able to design and implement experiments, and we need to be able to see the results of those experiments relatively quickly. There are some nice ideas using games1 and simple demonstrations and labs.2,3 I have found an example that is both entertaining for the students and rich enough in behavior to be an ideal platform for introducing scientific thinking: the automatic flushing toilet (Fig. 1).
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01.50.-i Educational aids

Using “Student Technology” in Introductory Physics: A Comparison of Three Tools to Study Falling Objects

Fábio Saraiva da Rocha, Fabio Fajardo, Maricarmen Grisolía, Julio Benegas, Robert Tchitnga, and Priscilla Laws

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 165

Online Publication Date: Feb 2011

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Being able to facilitate effective hands‐on laboratory experiences in introductory physics courses is a challenging task, even when contemporary laboratory facilities, equipment, and new technologies for data collection and analysis are available. At institutions without adequate resources, especially those in developing countries, we have found that the problem of providing effective laboratory experiences is especially daunting for at least two reasons: 1) the lack of equipment and contemporary measuring devices; and 2) even at institutions that have some laboratory equipment, students who have access to cell phones with digital timing and video capabilities or inexpensive digital cameras are bored with trying to use “old‐fashioned” apparatus for measurements.
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01.50.Pa Laboratory experiments and apparatus
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Demonstrations with an LCR Circuit

Yaakov Kraftmakher

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 168

Online Publication Date: Feb 2011

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The LCR circuit is an important topic in the course of electricity and magnetism. Papers in this field consider mainly the forced oscillations and resonance.1–5 Our aim is to show how to demonstrate the free and self‐excited oscillations in an LCR circuit.
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01.50.Pa Laboratory experiments and apparatus

The Light‐Emitting Diode as a Light Detector

William H. Baird, W. Nathan Hack, Kiet Tran, Zeeshan Vira, and Matthew Pickett

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 171

Online Publication Date: Feb 2011

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Alight‐emitting diode (LED) and operational amplifier can be used as an affordable method to provide a digital output indicating detection of an intense light source such as a laser beam or high‐output LED.1 When coupled with a microcontroller, the combination can be used as a multiple photogate and timer for under $50. A similar circuit is used as a data logging system for a mirror galvanometer, providing a record of changes in the Earth's magnetic field as small as a few nanotesla (nT).
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01.50.My Demonstration experiments and apparatus

An Introduction to Dimensionless Parameters in the Study of Viscous Fluid Flows

David Guerra, Kevin Corley, Paolo Giacometti, Eric Holland, Michael Humphreys, and Michael Nicotera

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 175 | Cited 1 time

Online Publication Date: Feb 2011

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It has been suggested that there is a need to deepen the understanding of fluid dynamics in the introductory physics course and to offer interesting experiments to do so.1 To address this need we have developed a laboratory experiment and the supporting analysis to demonstrate the role of viscosity and the interestingly mysterious use of dimensionless parameters in fluid dynamics.2 Since viscosity indicates the frictional dependence between the layers of a flowing fluid, a thoughtful student may ask why or when viscosity can be neglected. The laboratory experiment presented here uses common fluids to provide a concrete answer to this question and an easily understandable example of the role of dimensionless parameters in fluid dynamics.
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01.50.Pa Laboratory experiments and apparatus
01.40.gf Theory of testing and techniques
66.20.Ej Studies of viscosity and rheological properties of specific liquids

Exposing Students to the Idea that Theories Can Change

Chance Hoellwarth and Matthew J. Moelter

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 180

Online Publication Date: Feb 2011

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The scientific method is arguably the most reliable way to understand the physical world, yet this aspect of science is rarely addressed in introductory science courses. Students typically learn about the theory in its final, refined form, and seldom experience the experiment‐to‐theory cycle that goes into producing the theory. One exception to this is the Powerful Ideas in Physical Science curriculum (PIPS) developed by the American Association of Physics Teachers.1 In this curriculum students develop theories based on experiments. The “Heat and Conservation of Energy” unit illustrates the experiment‐to‐theory cycle in a set of experiments introducing the conservation of energy. The idea of conservation of energy is developed early in the unit; however, students must expand their idea of energy in order to incorporate new phenomenon, namely the specific heat and phase transitions. Yet even with these experiments, the ideas of energy and of a theory remain abstract. In order to address the abstractness of energy, many authors have introduced energy diagrams.2–5 In these energy diagrams, the height of a bar graph represents the amount of different types of energy, nicely illustrating how energy transfers from one form to another. The PIPS curriculum took this one step further and used area to represent thermal energy when mixing different amounts of water. Thus, the conservation of area illustrates the idea of conservation of energy. Using this as a starting point, we have extended the energy/area diagram so that it includes other aspects of thermal energy, making the idea of a theory more concrete. Every new experiment requires a change in the theory and hence a change in the corresponding energy diagram. In this paper we develop this enhanced energy diagram through a series of experiments taken from the PIPS curriculum. While PIPS is designed for nonscience majors, this sequence of events as a lab or as demonstrations would work for any introductory course. The sequence involves four experiments. We will describe each of the experiments the students perform and the typical results. Then we describe the theory building that subsequently adapts the energy diagram to explain new data. This will demonstrate how the theory building takes place and how the energy diagram is developed based on experimental results.
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01.50.My Demonstration experiments and apparatus
01.40.gf Theory of testing and techniques
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More on Faraday's and Lenz's laws ‐ Qualitative demonstrations

Roberto Hessel

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 184

Online Publication Date: Feb 2011

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A large variety of simple setups for demonstrating Faraday's and Lenz's laws have been described in the literature.1–4 For a few semesters, we tested some of these setups, especially those suggested in Ref. 1, but recently we decided to develop our own version.
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01.50.My Demonstration experiments and apparatus

Physics Teaching Experience

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 185

Online Publication Date: Feb 2011

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As we saw in the January 2011 column, less than half of the teachers who teach high school physics have a degree in physics or physics education. However, this does not necessarily imply that the teachers are not qualified to teach physics. It is likely that some of the non‐degreed physics teachers began teaching physics at the request of a principal or science department leader and liked it enough to seek additional training that did not lead to a formal degree. For example, some teachers have told us about NSF‐funded summer programs that they attended that dramatically affected the way they teach physics. Furthermore, the teachers learn from experience. About two‐thirds of physics teachers have taught physics for as many or more years than they have taught any other subject. The figure shows the relationship between a teacher's physics teaching experience and the type of physics degree they hold. In the April issue of The Physics Teacher, we will highlight demographics of high school physics teachers. If you have any questions or comments, please contact Susan White at swhite@aip.org. Susan is Research Manager in the Statistical Research Center at the American Institute of Physics and directs the high school survey.
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01.40.gb Teaching methods and strategies
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Inertia in Action

Diane Riendeau, Column Editor

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 186

Online Publication Date: Feb 2011

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Special thanks to Jennifer Groppe (Maret School) and Shannon Mandel (Barrington High School) for their help with this month's column.
If you use YouTube videos in your classroom, please send the link and a brief description to driendeau@dist113.org.
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01.50.ht Instructional computer use
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A hot wire

Boris Korsunsky, Column Editor

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 187

Online Publication Date: Feb 2011

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Abstract Unavailable
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01.50.-i Educational aids
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Binding together bonds

Ken Rideout

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 188

Online Publication Date: Feb 2011

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Many years ago when I was in high school, I asked my AP® Chemistry teacher, “Why is there a negative sign in front of the 13.6 eV in the table of electron energies? What does it mean to have negative energy?” She told me it had something to do with potential energy and not to worry about it. Well, I am still worrying about it.
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01.50.Kw Techniques of testing
01.40.gb Teaching methods and strategies
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Fermi Questions

Larry Weinstein, Column Editor

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 188

Online Publication Date: Feb 2011

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Abstract Unavailable
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01.50.-i Educational aids
01.40.-d Education
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Simple PowerPoint Animation

Leo Takahashi

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 189

Online Publication Date: Feb 2011

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The use of animation as a teaching tool has long been of interest to the readers of and contributors to this journal.1–5 While the sophisticated techniques presented in the cited papers are excellent and useful, there is one overlooked technique that may be of interest to the teacher who wants something quick and simple to enhance classroom presentations: PowerPoint animation.
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01.50.ht Instructional computer use
01.40.gb Teaching methods and strategies
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Simple terminal velocity measuring device

Wojciech Dindorf

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 190

Online Publication Date: Feb 2011

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Abstract Unavailable
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01.50.-i Educational aids
06.30.Gv Velocity, acceleration, and rotation
45.05.+x General theory of classical mechanics of discrete systems
01.40.-d Education
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Relativity and the Lead‐Acid Car Battery from PRL Focus, focus.aps.org/story/v27/st2#author

Dan MacIsaac, Column Editor

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 191

Online Publication Date: Feb 2011

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Abstract Unavailable
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01.50.-i Educational aids

HS physics teachers from Modeling‐L podcasting their classes

Frank Noschese and Paul Bianchi

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 191

Online Publication Date: Feb 2011

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Abstract Unavailable
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01.50.ht Instructional computer use
01.40.gb Teaching methods and strategies

Blue laser pointers are now affordable, www.amazon.com

Dan MacIsaac, Column Editor

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 191

Online Publication Date: Feb 2011

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Abstract Unavailable
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01.50.-i Educational aids
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Books on Thermodynamics: Reviews by the Book Review Editor

John L. Hubisz, Column Editor

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 192

Online Publication Date: Feb 2011

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Abstract Unavailable
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01.30.Vv Book reviews
05.70.-a Thermodynamics
01.40.-d Education
01.50.-i Educational aids

MicroReview by the Book Review Editor: Emmy Noether's Wonderful Theorem (with lots of questions and exercises),: Dwight E. Neuenschwander

John L. Hubisz, Column Editor

The Physics Teacher -- March 2011 -- Volume 49, Issue 3, pp. 192

Online Publication Date: Feb 2011

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Abstract Unavailable
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01.30.Vv Book reviews
01.50.-i Educational aids
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