Physics Demonstrations at Cal Poly Pomona
Demo Index:
Pira Index:
Title:
Description:
Demonstrates that the charge is stored on the dielectric of a capacitor.
Equipment:
1. Wimshurst machine (or Van de Graaff)
2. Leyden jar (dissectible)
3. Discharging tongs
4. PVC pipe (1/2 in., about 12 in. long)
5. 2 copper wires
6. Clear plexiglas box
Note: Leyden jar can be used w/ Van de Graaff instead of Wimshurst. (needs only #'s 1, 2, 3, 4, & 6)
Procedure:
1. Set up as shown, 1 copper wire to outer cup of Leyden jar, other wire to handle of inner cup.
2. Charge jar by cranking Wimshurst.
3. Using PVC pipe, carefully remove inner cup of Leyden jar. Grab glass by the edge & remove from outer cup. Place on plastic box.
4. Connect the inner metal cup with outer metal cup using the discharge tongs (no spark).
5. Using PVC pipe, reassemble jar. Connect inner and outer pieces using discharge tongs (spark).
Caution: to discharge the Wimshurst, carefully swing the discharge arms to the middle of the apparatus until they touch.
