Session J6: AAPTCOLL: AAPT College Teaching

Franck-Hertz Classic Experiment Automatization for the Modern Physics Laboratory

We will present a setup of the classic experiment developed by James Franck and Gustav Hertz using the software LabView. As in the classic experiment a cathode is heated producing electrons which are accelerated by an accelerating voltage, instead of the Mercury vapor used by Franck and Hertz we will deal with Neon. We will look at the spectral response of the Neon as a function of filament current in the electron gun. The automatization of the experiment will allow the users to explore details of the experiment that otherwise are easily hidden by technical complications that arise during experimentation.   

Assessing Critical Thinking

Based on the basic features of cognitive structure, it is possible to write an operational definition of critical thinking for use in assessment and in the development of assessment instruments. We discuss the need to assess critical thinking skills, in addition to content knowledge, problem solving and other skills, and the need for the inclusion of this type of assessment in the evaluation of changes in instructional methods and the comparison of classes taught by different instructional methods.   

Relativity and the standing electromagnetic wave

This PowerPoint presentation attempts to answer 4 questions. What could cause the effects of Relativity? Why do these effects depend only on the relative velocity between the observer and the object? Are these effects real or only apparent? Is there anything that can be used to physically illustrate these effects? In the presentation I will discuss a standing electromagnetic wave moving past an observer. The observer sees that the effects of relativity on the standing wave are caused by the Doppler Effect on the two waves creating the standing wave.   

How Batteries Fail

Batteries are series and/or parallel sets of individual voltaic cells, each characterized by an emf (electromotive force) and an internal resistance. A voltaic cell, with two electrodes separated by ion-containing electrolyte, supports chemical reactions at each electrode-electrolyte interface, involving ions in the electrolyte and both atoms and electrons in the electrode. The chemical reactions drive an electric current, and are responsible for the cell emf (electromotive force). Moreover, ions in the electrolyte are largely responsible for the electrolyte conductance, which determines the internal resistance. As the cell discharges, the ion density decreases, causing a rate of decrease of the conductance proportional to the current. A simple model that treats the ion density as always uniform can explain numerous aspects of the discharge curves (current vs time or current vs total discharge), including the precipitous fall in current when the internal resistance becomes comparable to the load resistance.   

An Analysis of Acceleration in Projectile Motion

Examination of the normal and tangential components of a projectile in free fall in comparison to the net downward acceleration relates to several concepts that are often mentioned briefly if at all in introductory courses. This may not be part of course material but can be an interesting resource for explaining projectile behavior.   

Physics in ``Polymers, Composites, and Sports Materials" an Interdisciplinary Course

The undergraduate science course described uses the themes of polymers and composites, as used in sports materials, to teach some key concepts in introductory chemistry and physics. The course is geared towards students who are interested in science, but are still completing prerequisite mathematics courses required for science majors. Each class is built around a laboratory activity. Atoms, molecules and chemical reactions are taught in reference to making polyvinyl acetate (white glue) and polyvinyl alcohol (gel glue). These materials, combined with borax, form balls which are subsequently used in physics activities centered on free-fall and the coefficient of restitution. These activities allow the introduction of kinematics and dynamics. A free fall activity involving ice pellets, with and without embedded tissue paper, illustrates the properties of composites. The final series of activities uses balls, shoes, racquets and bats to further illustrate dynamics concepts (including friction, momentum and energy). The physical properties of these sports objects are discussed in terms of the materials of which they are made. The evaluation plan to determine the effectiveness of these activities and preliminary results are also presented.   

A Lab Activity Investigating Newton's Third Law

A typical MBL-type laboratory activity for student investigation of Newton's Third Law will be reported. Student's responses to a number of questions to check their understanding as they go through the activity will be presented.