This one can be messy but it shows how like charges repel quite dramatically.
Watch Video:
Other Demos of Interest:
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Pie Plates on a Van der Graaf |
Van der Graaf Sparks |
Ion Wind from Van der Graaf |
Teachable Topics:
- Van de Graaff Generator
- Coulomb Repulsion
Theory:
This demonstration is based on the same concepts explained in the Flying Pie Plates Demo A shallow pie plate of Styrofoam peanuts is placed on top of the Van de Graaff generator’s sphere and charged up. Each of the peanuts gains a negative charge from the excess electrons and tries to repel the others as it is also repelled by the negatively charged sphere. The result effect is similar to a fountain as the peanuts spray out of the box and away from the sphere. The more peanuts, the better effect, but also a bigger mess!
Apparatus:
- Van de Graaff generator and grounding rod
- Shallow aluminum dish (a large rectangular one works best
- Styrofoam peanuts (the more the better!
Procedure:
- Fill the aluminum tray with as many Styrofoam peanuts as it will fit.
- Plug in the Van de Graaff generator into an outlet and the grounding rod into the generator.
- Place the aluminum tray of peanuts on top of the generator’s sphere.
- Using the grounding rod, turn on the generator and watch the peanuts float out of the tray!
- Turn off the generator with the grounding rod and discharge the sphere by touching it with the grounding rod.
SAFETY WARNINGS
- Always turn the generator on and off with the grounding rod
- Stand clear of the generator once it has been turned on
- Always discharge the generator by touching the metal sphere with the grounding rod after having turned it off
