Embedded Files
Demo - Van de Graaff Generator. Pie plates, soap bubbles, arcing, shocking people, hair standing on end, spinner thingy, coronal discharge - give a kid a mohawk. If your Van de Graaff isn't charging, clean the outside of the dome itself, and sand any burrs or rough spots, and clean the inside of the clear riser tube that connects the dome to the base. Always have a spare belt, and don't run the generator so fast that the belt sways back and forth.
Demo - Sheet of Rubber. Students stretch a sheet of lycra out. I show large and small size positive and negative charges. (Geometric size, as well as magnitude) Talk about how the slope of the sheet is the field, positive charges push it up, negative down. I show how pointy protrusions create strong fields (steep slopes) I get a couple of small whiteboards and show how the field is very uniform between two parallel plates, and then move them apart to see the limitations of this as their separation gets large compared to their width.
Lab - Electric Field Mapping - Students map the equipotential lines in a shallow pan of water that has electrodes in it. A graphite pencil is their test probe and marker. Once they have the lines of equal potential, they they draw electric field lines perpendicular to them and perpendicular to the conductors. It's a cool old lab I did in college.
Lab - Millikan Oil Drop Simulation - an old (1988) DOS simulation from Vernier that still works in DOS box. I have each child get their own unique 25 points, and then have them combine their data with three other students. I show how to use the software on the help site:
Lab - RC Circuits - Students study the exponyential decay of the voltage on a capacitor that is connected to a 1 Meg Ohm resistor. It uses an OLD Vernier voltage probe that has the orange +5.00 V wire from the power supply of the interface.
Demo - Charge by Friction, Conduction, Induction using silk and rabbit fur and the projection electroscope.
Demo - Cathode Ray Tube. (IB requires students to learn about CRT - haha) Be careful here - the high voltage source is dangerous. Once you get it going, you can show them what a magnet brought in sideways to it does to the beam. (Right hand rule) You can also get the Van de Graaff dome to repel the beam of cathode rays, proving that the VdG charges negatively.
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