Program

9^th Annual Spring Meeting

North Carolina Section

American Association of Physics Teachers

March 26-27, 2004

Meredith College

3800 Hillsborough Street

Raleigh NC 27607

Abstract Deadline: March 8, 2004

Check out our Web site http://www.physics.ncsu.edu/ncsaapt/

Program

Friday, March 26, 2004

5:30 Registration (Atrium outside 101 Ledford)

7:00 PM, 101 Ledford (#21 on the map): The First Man Made Nuclear Explosion, Worth Seagondollar, former Head of the Physics Department, North Carolina State University, Raleigh NC 27695-8202

After the discovery of the neutron in 1932, and the discovery of artificial radioactivity in 1934, Enrico Fermi at the University of Rome embarked on a program to create heavy elements via neutron capture on uranium - element 92. He made element 93, now called neptunium, and other activities that he erroneously attributed to elements 94, 95, & 96. Ida Noddack, a German chemist, thought Fermi had caused fission and attributed the activity to lighter elements. But her paper was not widely read and only when Hahn and Strassman repeated Fermi’s experiments in 1939 was it understood that the intense radioactivity was due to fission. Quickly, it was discovered that the Q-value was a gigantic 200 MeV and that free neutrons were also emitted, making a chain reaction possible. The possibility of a tremendous energy source came at a time when World War II was just starting. Information reached the British that the Germans were working on a nuclear weapon. Soon the Manhattan Project was started in the USA that culminated in the development of the first atomic bomb. I was a junior scientist at Los Alamos and helped determine the critical mass for plutonium. I was 9 miles away from the first man-made nuclear explosion in New Mexico. I will talk about some of my experiences during that time.

8:10 PM: Analysis of Light Curves for Novae in M31, Katie E. Scholl, Cape Fear High School, 736 Three Wood Drive, Fayetteville, NC 28312, (910) 323-4509, email: flutterby16@vol.com

Light curves from novae can be used to estimate the masses of the white dwarfs that produced them. Subrahmanyan Chandrasekhar predicted that white dwarfs with masses greater than 1.4 solar masses could not exist. We analyzed light curves from several years of M31 (Andromeda Galaxy) images to see if we could test the Chandrasekhar limit on white dwarf mass.

8:25 PM: Path Sampling Monte Carlo Method for Modeling Sediment Transport Processes over Complex Terrain, Christopher S. Thaxton, Helena Mitasova, Lubos Mitas, Department of Physics, North Carolina State University, 3139 Jordan Hall, NCSU, Raleigh, NC 27695-8202, 919-515-8596, Fax: 919-515-7802, mailto:csthaxto@unity.ncsu.edu

We present a path sampling Monte Carlo method for solving the governing differential equations for landscape-scale soil detachment, transport, and deposition over complex terrain, soil, and cover conditions. Landscape-scale simulations are evolving from empirically-based, spatially averaged, static models to process-based, distributed, dynamic models. Our approach, one of the new breed of environmental models, exploits the particle-field duality in which the landscape (the continuous field) is sampled at every time step and the collection of representative particles (walkers) is evolved in a manner similar to the time evolution operation used in quantum mechanics.

The model can be made arbitrarily accurate by increasing the number of walkers. The suite of distributed input parameters includes a water diffusion coefficient, transport capacity, soil erodibility, critical shear stress, and a surface roughness coefficient. We present model results of water and sediment flow as well as sediment erosion and deposition patterns for various watersheds. In addition, recent advances in the model allow for the evolution of the terrain for short time scales on the order of one year. The influence of transport mechanisms on short-term and long-term topological changes induced by human impact, such as mining, urbanization, and military operations, may lead to the determination of the optimized measures to more cost effectively meet emerging environmental control requirements. The model is open source and can be run from Grass GIS.

8:45 PM: Social Gathering with Snacks

Saturday

Saturday papers will all be presented in the Science and Mathematics Building (#28 on the map)

9:00 AM: NCS-AAPT Plans for the World Year of Physics, Chuck Stone, Department of Physics, North Carolina, A&T State University, 1601 East Market Street, Greensboro, NC 27411, (336) 334-7646, Fax: (336)256-0815, mailto:cstone@ncat.edu

The AAPT challenges its local sections to come to the Sacramento summer meeting ready to discuss their outreach plans that their members are committed to pursuing for the World Year of Physics in 2005. During this presentation, I would like to moderate an open, interactive discussion where we will make commitments to lead physics outreach programs in 2005 either as individuals, separate departments, or as a statewide group of physics teachers. Some ideas you may consider include community-based events (movie night, meet a physicist, host a public discussion, science trivia night, tours of your facility, placing science facts in local shops, physics demonstration shows, etc.); teacher-led events (hold a physics day, host family science events, start a science club, run a science Olympics, host a scientist-in-residence, etc.); and department-led events (host an open house, feature a series of science speakers, SPS activities, etc.). More ideas can be found at http://www.physics2005.org/ and in the January 2004 issue of The Physics Teacher. Come share the outreach programs you are willing to initiate and lead.

9:15 AM: How Accurate Are the Measuring Devices Found in a Typical Introductory Physics Lab? Duane L. Deardorff, Dept. of Physics and Astronomy, The University of North Carolina at Chapel Hill, Campus Box 3255, Chapel Hill, NC 27599-3255, 919-962-3013, mailto:duane.deardorff@unc.edu.

Many introductory physics laboratory experiments are designed to have students empirically verify a fundamental physics principle. The ability to show that an experimental result agrees with a theoretical prediction depends in part on the assumption that the measuring devices used in the experiment are properly calibrated. Since most laboratory periods do not allow students time to check the calibration of each measuring device (and many people would argue that this is not the best use of lab time), it is helpful to supply students with expected accuracy specifications for the equipment they use. This talk will include an overview of the accuracy of typical physics laboratory instruments and tips for how to check the calibration of these devices. A sample instrument accuracy sheet can be found at: http://www.physics.unc.edu/labs

9:30 AM: Incorporating the Results of Physics Education Research into the University Classroom, Willyetta Brown-Mitchell, Department of Mathematics, Science, and Technology Education, Box 7801, North Carolina State University, Raleigh NC 27695, mailto:Brown-Mitchell@ncssm.edu NCSSM Dept. of Physics, Bryan 445, (919) 416-2766

Physics teachers' conceptions of teaching appear to influence students' approaches to learning in introductory physics. Physics education researchers have compiled a substantial amount of evidence that student course outcomes can be improved if research-based instructional strategies are incorporated into teaching. At the university level physics instructors find this evidence convincing and attempt to change their instruction. This paper presents the partial results of a case study of an experienced university physics instructor who attempted to change instructional practices. Although the instructor appeared to have all of the prerequisites for successful change, he still encountered difficulties. A synopsis of typical K-12 experiences that physics educators at the university level can emulate will also be presented.

9:45 AM: Break – Visit and thank our sponsors!

10:00 AM: Science Curriculum and Education Policy in NC Public Schools, Karen Palasek, John Locke Foundation, kpalasek@nceducationalliance.org

She is a policy analyst and publications' coordinator for JLF’s North Carolina Education Alliance. She is also an adjunct professor of economics at Peace College in Raleigh. Dr. Palasek has written several articles and book reviews related to education and home schooling for the magazine of the Foundation for Economic Education, Ideas on Liberty, and the North Carolina Education Alliance. Dr. Palasek holds a Ph.D. in economics from George Mason University, an MA in economics from the University of Connecticut, and a Bachelor of Music Education from the Hartt School of Music.

10:30 AM: Break - Visit and thank our sponsors!

10:45 AM: Diffraction Algorithms and Their Visualization, Wolfgang Christian and Mario Belloni, Davidson College

Diffraction is one of the most visually interesting and important topics in physical optics. The Fast Fourier Transform, or FFT, makes it easy to display Fraunhofer diffraction patterns from arbitrary apertures and many programs are available for displaying these patterns. Fresnel diffraction is, however, more difficult and few programs have been developed to help students explore this topic. We present implementations for two such algorithms and use them to demonstrate various optical phenomena.

This work has been supported in part by the National Science Foundation (DUE-0126439).

11:00 AM: Visualizing Quantum Mechanical Revivals, Mario Belloni and Wolfgang Christian, Davidson College

Localized solutions to the time-dependent Schrödinger equation, so-called quantum wave packets, have been of theoretical interest since the beginning of quantum mechanics. Such wave packet solutions are studied, in part, because they exhibit features that are central to the study of the classical limit of quantum mechanics. Over the last 20 years, the topic of quantum mechanical wave packet revivals (the fact that certain bound-state wave packets reform to their original shape in a predictable way) has received considerable theoretical attention and experimental verification. We briefly describe the standard methods for visualizing wave packet revivals and describe our suite of Java applets (both Physlets and the new Open Source Physics programs) that analytically or numerically solve and visualize the problem of a wave packet in an infinite square well.

This work has been supported in part by the National Science Foundation (DUE-0126439 and DUE-9752365).

11:15 AM: Some New Adaptations of Physlets, Donald F. Collins, Warren Wilson College, WWC 6017, PO Box 9000, Asheville, NC 28815, mailto:dcollins@warren-wilson.edu

Physlets are adaptable applets written by Wolfgang Christian and Mario Belloni of Davidson College. By controlling physlets through JavaScript, physlets can be adapted for practically any application in physics and astronomy instruction. The applications presented will be an interactive lunar phases module, and the motion of various inertial masses subject to the same retarding forces.

11:30 AM: Impact of Atomic Corrugation on Sliding Friction, Tonya Coffey, Sang Min Lee and Jacqueline Krim, North Carolina State University, 2808 Isabella Dr., Raleigh, NC 27603, 919-513-2685, Fax: 919-515-1333, tscoffey@unity.ncsu.edu

Tribology (from the Greek word "tribos", which means "to rub") is the study of friction, lubrication, and wear, an inherently challenging field requiring much interdisciplinary cooperation. With the advent of new experimental techniques emerging in the 1980’s, a new field involving friction studies at atomistic length and time scales, nanotribology, emerged. At the atomic scale, friction is believed to originate primarily via sliding induced excitation of phonons. [1] Theoretical predictions of the magnitude of phononic dissipation have been related to the atomic corrugation of the adsorbate/substrate potential. [2] Braun and colleagues [3] measured a corrugation of 1.9 meV for xenon on a copper (111) surface using helium atom scattering. Using the Quartz Crystal Microbalance (QCM), we have measured the sliding friction of Xe/Cu (111) adsorbed at 77 K. The QCM probe of sliding friction is the sliptime, which measures the slippage of the adsorbate atop the oscillating surface of the QCM. For monolayer coverages, we observed a sliptime of 10 ns for Xe/Cu (111). We also discuss theoretical predictions for the impact of atomic corrugation on sliding friction.

[1] Fundamentals of Friction; Macroscopic and Microscopic Processes, ed. I.L. Singer and H.M. Pollock, Kluwer, Dordrecht (1992).

[2] M. Cieplak, E.D. Smith, and M.O. Robbins, Science 265 (1994) 1209.

[3] J. Braun et al., PRL 80 (1998) 125.

11:45 AM: Twists 'n Things, Larry Ward, Catawba Valley Community College, mailto:lward@cvcc.edu

Small "twists" in the presentation of laboratory or class activities can enhance the engagement of student thinking toward discovering principles of physics. Samples of activities will be available.

Noon: Pyroelectric Crystal Accelerators for Production of 150 keV Electrons and 100 keV Positive Ions: Possibilities for Student Research, Stephen M. Shafroth, Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3255, e-mail shafroth@physics.unc.edu and James D. Brownridge, Department of Physics, Applied Physics and Astronomy, State University of New York at Binghamton, P.O. Box 6000, Binghamton, New York 13902-6000, mailto:jdb@binghamton.edu

We have studied acceleration of focused nearly monoenergetic high-energy electron and positive ion beams away from and towards the crystallographic z surfaces of LiNbO3 and LiTaO₃when they are heated and cooled in dilute gases. Electron spectra can be obtained using surface barrier detectors. They show a very interesting-multiple peak behavior i.e. peaks of energy E, 2E, 3E…. are detected. However no electrons of energies 2E, 3E …are produced which is shown by use of absorbers. Rather what appears to be happening is that when the crystal surface is negative on cooling with the – z base exposed, positive ions bombard the crystal and each collision with the surface gives rise to numerous Auger and secondary electrons. The positive ions arise from quantum mechanical tunneling of the residual gas molecules when they encounter a sufficiently strong electric field near the crystal surface. These electrons are then focused so as to form a beam. The ratio of the counts in the peaks at energy E to 2E for example can be altered by detecting electrons at various distances from the focal spot. Recently one of us (JDB) has found a most interesting new line of research: the transport of these high- energy electrons through metal and insulating tubes. The study of such phenomena are ideal for students wanting to get the flavor of research because the equipment is inexpensive, the experiments are quite safe and new phenomena are still to be found and explained. . Pyroelectric crystal electron accelerators can be used to excite characteristic K x-rays from tree leaves. Such studies connect physics and biology and are well suited for student projects

12:15 PM – 1:30 PM: Lunch and Business Meeting in Science and Mathematics Building

1:30 PM: Extend WebAssign to Create Innovative Question Types, Aaron Titus, 342 Haworth Hall of Science, Department of Chemistry and Physical Science, High Point University, 833 Montlieu Avenue, High Point, NC 27262, 336-841-4668, mailto:titus@mailaps.org, http://www.highpoint.edu/~atitus/

WebAssign will automatically grade typical web-based question types like multiple choice, multiple select, fill in the blank, and numerical questions. However, since the beginning of WebAssign, Larry Martin and I discussed grading things like a mouse-click on an image and sketches of vectors, graphs, ray diagrams, and any other kind of drawing. To facilitate these types of questions, the WebAssign staff developed a Java question type that allows a question author to use JavaScript and Java to handle many of WebAssign's tasks. For example, a molecule-drawing editor (JME) is used to grade students' drawings of organic molecules, and PADS (http://physics.wku.edu/PAD/) are used by Scott

Bonham to grade sketches of graphs, motion diagrams, and vectors. I have used this Java question type in WebAssign to grade a student's mouse click on an image map and to grade vector drawings (using Physlets written by Wolfgang Christian). I will demonstrate these WebAssign questions and will provide templates for WebAssign users interested in developing their own questions.

1:45 PM: Applications of Consumer Digital Cameras in Astronomy, Donald F. Collins, Warren Wilson College, WWC 6017, PO Box 9000, Asheville, NC 28815, mailto:dcollins@warren-wilson.edu

Moderately-priced consumer-grade digital cameras, which permit time exposure (up to 15-30 sec), can be used for color astronomical imaging both with and without a telescope. Applications range from wide field-of-view sky images, color identification of stars, planetary motion, variable star photometry (magnitude and color index), deep sky objects, and lunar images. This type of camera and the associated analytical techniques provide excellent interactive engagement activities for students enrolled in the general education courses of astronomy and physical science. Variable star measurements, color photometry, the camera limitations and typical noise, deep sky objects, and planetary motion will be presented. All observations presented were done with the Canon A60 digital camera. All analytical measurements and deep sky photographs require image stacking: the alignment and co-adding of multiple time-exposure frames made feasible by free software. Color photometry extraction has been accomplished by writing routines in Matlab.

2:00 PM: Undergraduate Experiment for Determining Thermal Demagnetization Properties of Ceramic NdFeB, Ken Rathbun and Dan Boye, Davidson College, P.O. Box 7133, Davidson, NC, 28035, USA, (704) 894-2649, FAX: (704) 894-2894, kerathbun@davidson.edu, (daboye@davidson.edu)

Quantum mechanical interactions at the atomic level give rise to long range ordering of electron spins in ferromagnetic materials. The long-range order disappears above a certain temperature called the Curie temperature, T_C. This temperature can be related to the exchange energy, the energy required to disrupt the order of the magnetic domains. We have developed an experiment for students in our Modern Physics (Physics 320) course to determine T_C of the ferromagnetic ceramic NdFeB. Measurements show that the magnetization drops by 97% at 290°C, which compares well with the nominal T_C for NdFe of 320°C. Inclusion of boron and other additives in the ceramic matrix reduces T_C. The permeance coefficient of the magnet can be determined from the shape of the demagnetization curve. While still above T_C, the material can be placed in an external magnetic field in order to restore the material to its original state.

2:15 PM: A Few Notes on How to Make Your Course Self-Paced, John L. Hubisz, North Carolina State University, Raleigh, NC, 27695-8202, Hubisz@unity.ncsu.edu

Over the course of 35 years, approximately 20% of my students opted to take my courses self-paced. I will present a few quick notes on the procedure for the first semester of an algebra-trigonometry-based course.

2:30 PM: Take Five (Five minute presentations on any interesting topic for the classroom)

Workshops

2:30 PM: Introduction to vPython, Joe Heafner, Catawba Valley Community College, 3990 Herman Sipe Road NW, Hickory, NC 28602, 828-327-7000, ext. 4246 (W), mailto:heafnerj@ctc.net

VPython is an easy to learn programming environment designed to accompany the innovative Matter & Interactions curriculum developed by Ruth Chabay and Bruce Sherwood (both of NCSU). The VPython packages are freely available from <http://www.vpython.org> and are available for Windows, Linux, and Mac platforms. In this workshop, we will demonstrate several sample programs and then lead participants through two of the same tutorials students actually use in the classroom. We hope participants will be amazed at how easily real physical systems can be modeled in VPython. While specifically designed to accompany Matter & Interactions, VPython could be used in any introductory physics curriculum.

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4:00 PM – 7:00 PM: East Texas Chili at the Hubisz’s – On leaving Meredith College, turn right, turn right again immediately after the underpass. You are now heading south toward Apex and Sanford on IH 440 and Highway 1. Pass IH 40 exit, pass Cary Parkway exit, pass Highway 64 exit, pass Highway 1010 exit, and then turn right at Exit 95 (Highway 55 with Holly Springs & Fuquay-Varina East and Apex West). At Exit 95 (you have now been traveling approximately 12 minutes), turn right (west) toward Apex on Highway 55. At the third traffic light (the one after the railroad underpass), turn left (South Salem Street). Go 1.9 miles. The railroad tracks will be on your left all the way. Go past the Shangri-La Motor Court, go past Apex-Barbeque Road, and at 1.9 miles you will see a large black mailbox on the right with “HUBISZ” and “1604” on it. Turn right immediately after the mailbox, making about a 180^o turn. Follow the driveway for about 0.3 mile.

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Warning

Many members are past due with dues. Each time that the secretary-treasurer receives $5.00 in your name your dues are bumped up one year, so if you are listed as a member joining in 1998 and your Dues column reads 2000 and you pay $5.00, it is changed to 2001 and you are still behind. Your dues help with awards, mailings, and other expenses for running the organization. Dues are $5.00 per year or $100 lifetime.

Awards

(Note that authors of papers to be considered for the Best Graduate Student paper are underlined and those for the Best Undergraduate Student paper are in italics.)

There is a $100 prize for the best undergraduate student paper, a $100 prize for the best graduate student paper, and a prize of $150 towards expenses to present a similar paper at a national meeting suitably noting the support of the NCS-AAPT for the best pedagogical paper. Please keep notes and make recommendations to any section officer to aid in their choice. Mario Belloni is chairman of the Awards Committee. A new award designed to recognize superior undergraduate students has been established that carries with it an award of $100. There is also the Walter C. Connolly Award ("An award to recognize outstanding pre-college teachers in the Section.") There is also the John L. Hubisz Award (An award to recognize an individual for significant service and contributions to the Section.) Please check out these awards on the Web site and send your nominations to Mario and/or Bo Wessell. We thank our sponsors for contributing to support these awards.

At the last Fall Meeting in Wrightsville Beach the prize of $100 for the Best Undergraduate Student paper went to Bryan Nelsen of Georgia Southern University for “Index of Refraction Profile in a Highway Mirage.” The prize for the Best Pedagogical Paper went to Harlan Devore of Cape Fear High School for “Interactive Excel for the Science Classroom.” (For a copy of his CD, send a note to him at mailto:Hdev48@aol.com.) He will receive $150 toward expenses to attend a national meeting to present a similar paper.

Business

The NCTYCPA will be holding elections at lunchtime as part of their business meeting.

At the NCS-AAPT business meeting we will be voting on the changed wording of the Constitution and Articles of Incorporation, which will set the times of newly-elected individuals taking office.

An election will be held for the positions of Vice-President (John Hubisz has been nominated), Two-Year College Representative (Joe Heafner has been nominated), and Secretary-Treasurer (Mary Creason has been nominated.) Self-nominations accepted!

Sharon Schulze is interested in developing a Physics Teacher Alliance for the Triangle in which physics teachers and physical science teachers could meet occasionally to share ideas and generally interact. Contact Sharon Schulze, Ph.D., Associate Director, The Science House, Suite 1200, 909 Capability Drive, NC State University Centennial Campus, Box 8211, NC State University, Raleigh, NC 27695-8211, http://www.science-house.org 919-515-9403 Fax: 919-515-7545

Next Meetings

We meet on October 29^th and 30^th this Fall at Davidson College where our hosts will be Mario Belloni, Dan Boye, Larry Cain, and Wolfgang Christian.

We need a volunteer location for the Spring 2005 Meeting.

We meet in the Fall of 2005 at University of North Carolina – Pembroke where our host will be José D’Arruda.

Meredith College Campus Map

http://www.meredith.edu/visitors/campus-map.htm

Local Arrangements

Snacks and drinks will be available on Friday evening during the Social after the papers are presented. Coffee, rolls, and juice will be available Saturday morning. Lunch will be a catered meal from the campus dining service consisting of specialty sandwiches, chips, cookies, drink, etc. We will meet in a separate room in the Science and Mathematics Building where we will also have our business meeting, including the election. Soft drinks and snacks will be available Saturday afternoon.

There will be overhead projectors for Power Point presentations in all the session rooms as well as DVD/VCR/CD audio and visual capabilities.

The Ramada Inn/Blue Ridge at 1520 Blue Ridge Road, Raleigh NC 27607, (919)832-4100 and the Brownestone Hotel/Holiday Inn at 1707 Hillsborough Street, Raleigh NC 27605, (919)645-1024 are our best bets for accommodations. Ask for the discount and mention the NCS-AAPT Meeting.