Electricity and Magnetism
5B30.50: Electrostatic pinwheel
Description: This demonstration shows that a pinwheel on a Van de Graff generator will spin.
Equipment:
- Van de Graff machine
- Metal discharge wand
- Pinwheel (either large or small)
Setup Procedure:
- Plug the Van de Graff machine into a table with a three prong plug (ground prong); else you risk getting shocked when turning it off.
- Connect the metal discharge wand to the black grounding post on the Van de Graff machine.
- With the machine off, set the speed to about 1/2 speed.
Demonstration Procedure:
- Balance the pinwheel on the top of the Van de Graff dome.
- Turn the Van de Graff machine on while holding the discharge wand in the other hand.
- Note that the Pinwheel starts to rotate. This is because electric fields concentrate at a point, so when voltage gets high enough, ions will spray off the point into the air.
Like charges repel - the point will push the air away, and the air will push the point away.
High Voltage
Due to the high voltage, keep away from sensitive electronics.
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