Van de Graaf

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142 Friday 4/19 was a day when it was nice to forget all the things going on in the world and have some fun. Despite the rainy weather, the Van de Graaf generator was working up a nice electric potential, and we successfully made a number of students’ hair stand away from their heads. I love the Van de Graaf generator. (It was also the day of the spring pep rally. My students usually do not wear glitter on their faces.)

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Capacitance

IMG_20130307_102401114 The AP class is making capacitors out of aluminum foil placed between the pages of books. We are hoping that the capacitance is proportional to area, inversely proportional to the distance between the plates, and we also hope to determine the dielectric constant of textbook paper.

Equipotentials

IMG_20130228_095447110 We experimentally determined equipotential lines in AP physics today, using digital multimeters and carbon-infused conductive paper. It was a small class due to DECA, the musical, and a swim meet, so a bunch of kids will have to make it up, but that should not be too bad. I’ll be putting these pretty drawings on the bulletin board.

Potential

20130226-144501.jpg107 One of the things I love about Excel is making 3-D surface charts. Here a student has placed three charges and has entered formulas to calculate the electric potential at a grid of points around the region where the charges are. You can find instructions in this pdf by Bob Beichner. The instructions have been published in The Physics Teacher [Phys. Teach. 35, 95 (1997)].