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COMMENTARY

From Stephanie Chasteen, University of Colorado - Boulder

We used this activity as the basis for an upper-division (junior-level) tutorial in E&M at our university. We found a surprising amount of student difficulty in setting up the integral to find E from a ring of charge, especially in setting up Griffiths' “script-r”. We used an amended version of OSU's “Star Trek” activity in order to discuss script-r. Students were not comfortable with this notation or the direction of script-r, and the tutorial was valuable. There was some difficulty in translating from cartesian to cylindrical or spherical coordinates. After practice in using script-r in one part of the tutorial, they continued to have difficulty in extending this understanding to a new situation. In doing the actual integral, many students were confused about how to integrate over a vector (are there one integral or three?).

Our tutorial, plus detailed comments, are attached.

• Tutorial 1 - Charged bike tire3310_tutorial_final.pdf
• Tutorial 1 - Instructor's handbook3310_tutorial1_manual_final.pdf