TOPIC:

ID Code: J4-32
Purpose: Demonstrates that capacitors store electrical energy
Description: A 3500 microfarad capacitor is charged to 100 volts using the battery pack. Touch the capacitor terminals to the copper contacts on the battery pack; check that the polarity is correct, this is an electrolytic capacitor. Discharging the capacitor with the large screwdriver produces a very loud BANG.
Availability: Available

I really like this one to start the discussion of electrostatic energy; it leaves an impression on the class.
Works well if you (with supervision) ask a volunteer to do it. Bring a DVM and you can check that a nominal
67.5 V battery will have a larger voltage if fresh -- we got ~70V. That was worth a discussion also.