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July 13–17, 2013
Tuesday morning
be the mass of the central object. While historically accurate and useful
for our Solar System, this approach leaves students ill-prepared to apply
their understanding of orbits to most modern astronomical discoveries.
In particular, students cannot use this form of Kepler’s law to explore how
the Doppler velocity method is used to characterize newly discovered
exoplanets. I propose an alternate path to Kepler’s law that both preserves
the observational importance of velocity and includes the motions of both
objects, while still maintaining the elegance and pedagogical simplicity.
With exciting developments in the news and real data easily accessible,
exoplanet science presents a valuable new opportunity to motivate students
and change how we teach about orbits.
DB07:
11:30-11:40 a.m. On Equivalent Resistance
Contributed – Mikhail Kagan, PennState Abington, 1600 Woodland Road,
Abington, PA 19001;
One of the basic tasks related to electrical circuits is computing equivalent
resistance. In some simple cases, this task can be handled by combining
resistors connected either in series or in parallel, until the original circuit
reduces to a single element. When this is not possible, one resorts to the
“heavy artillery” of Kirchhoff’s rules. What traditionally receives little to no
attention in the introductory E&M class is the method of nodal potentials.
At the same time, it may often be both mathematically and conceptually
simpler. In this talk, I will review the method of nodal potentials and use
it to find the unknown currents and voltages in the Wheatstone-Bridge-
like circuit. At the end, I will derive —in a closed form—the equivalent
resistance of a generic circuit. The latter result unveils a curious interplay
between electrical circuits, matrix algebra, graph theory and its applica-
tions to computer science.
DB08:
11:40-11:50 a.m. Modifying Gauss’s Law for Two-
Dimensional Electric Fields
Contributed – David Keeports, Mills College, 5000 MacArthur Blvd., Oakland,
CA 94613;
While the electric field due to a point charge is inversely proportional
to the square of the distance from the point, the electric field due to an
infinite line of charge is inversely proportional to the distance from the
line. This talk will consider charge configurations built from parallel
infinite lines of charge. For such charge configurations, the electric field in
the xy-plane fully determines the electric field everywhere in space, and
Gauss’s law can be reformulated in terms of an integral of the electric field
around a closed planar loop. A proof of “two-dimensional Gauss’s law”
will be presented. This proof closely parallels the proof of Gauss’s law from
Coulomb’s law and is well adapted to the instructor’s planar blackboard and
to the student’s page.
DB09:
11:50 a.m.-12 p.m. Creative Exercises in Introductory
Physics
Contributed – Delena Bell Gatch, Georgia Southern University, PO Box 8031,
Statesboro, GA 30460;
Creative exercises are a new alternative to traditional assessments. During
creative exercises students are given a prompt and asked to write down as
many distinct, correct, and relevant facts about the prompt as possible. The
prompt does not pose a direct question for students to answer; instead the
prompt is open ended. Students receive credit for each correct fact they
include which is related to the prompt and distinct from the other facts
they list. Creative exercises encourage students to focus on the physical
situation presented instead of the question posed. Multiple examples of
creative exercises developed and implemented in an introductory physics
course will be presented. The benefit of using creative exercises to promote
students’ mastery of the course material will be described. In addition
students’ perceptions of the impact of creative exercises on the learning
process will be discussed.
DB10:
12-12:10 p.m. Making Learning Physics “Phun”
Contributed – Samya Zain, Susquehanna University, 514 University Ave.,
Selinsgrove, PA 17870;
In a small liberal arts college, like Susquehanna University, students come
to the Introductory Physics class with all backgrounds. For my classes,
I prepared crosswords mostly comprising important vocabulary words
from the chapter. They were offered as a part of extra credit towards the
final grade, and were due before the start of every chapter. The crosswords
are structured such that they did not require a lot of effort; however they
made a huge impact in terms of a student’s familiarity with the materials.
The strategy for team ork is simple and recognized widely as a good way
to engage the students. I have tweaked this to include “team quizzes.” In
a graded team quiz, all students make sure that their team members con-
tribute, since the team is only as good as its weakest link. This strategy has
delivered mixed results, depending on the individual student and the team
dynamic, from panic to triumph to ah-ha moments.
DB11:
12:10-12:20 p.m. Why Are Pigeons’ Heads Purple or
Green but Never Red?
Contributed – Lawrence B. Rees, Brigham Young University, Department of
Physics and Astronomy, BYU Provo, UT 84602;
We know that thin film interference is responsible for a number of effects
such as the variable color of birds’ feathers and the colorful reflection of
soap bubbles. But it is a difficult thing to explain why a pigeon’s green
feathers look purple and its purple feathers look green when viewed at
oblique angles or why there are alternate pink and green stripes between
white bands in a soap film. A short PDF presentation (available online)
with embedded animations shows how these phenomena can be under-
stood in terms of the absorption spectra of cone pigments and pseudo-
primary colors. Soap films are analyzed with reflection spectra that vary
with film thickness. Pigeon feathers are analyzed with reflection spectra
that vary with observation angle.
Session DC: Best Practices in
Educational Technology
Location: Broadway I/II
Sponsor: Committee on Educational Technologies
Co-Sponsor: Committee on Research in Physics Education
Date: Tuesday, July 16
Time: 10:30 a.m.–12:30 p.m.
Presider: Andrew Gavrin
DC01:
10:30-11 a.m. RAWR: Rapid Assessment and Web
Reports
Invited – Scott Franklin, Rochester Institute of Technology, Department of
Physics/RIT, Rochester, NY, 14623; United States
Eleanor Sayre, Kansas State University
Physics courses are structured so as to build upon prior knowledge. Kine-
matics concepts are used to learn dynamics, which themselves are used in the
study of energy, momentum, and conservation. When this assumption fails,
however, the results can be mystifying. Why, for example, should instruction
in circuits hurt students’ understanding of Newton’s third law? Surprisingly,
new knowledge can negatively impact student understanding (interference},
suggesting a more subtle dynamic than simple layering. In this talk I will
describe recent technological advances that allow instructors to investigate
student learning on a finer time scale than pre-/post-testing. RAWR (Rapid
Assessment and Web Reports) contains web-based conceptual quizzes, the
ability to upload extant data, and easy-to-use online analysis techniques. The
pedagogical consequences are immense, allowing instructors to consider
how new topics reinforce or interfere with prior knowledge, and adapt their
instruction to the particular state of their students.
DC02:
11-11:30 a.m. Flipping Intro Physics at the University of
Illinois
Invited – Mats A. Selen, University of Illinois, Department of Physics, 1110 W.
Green St., Urbana, IL 61801;
