5B30.50: Electrostatic pinwheel


Video: Watch this demo

Instructor’s video

Description: This demonstration shows how a pinwheel on a Van de Graff generator will rotate.


  • Van de Graff machine
  • Metal discharge wand
  • Pinwheel (either large or small)

Setup Procedure:

  1. 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.
  2. Connect the metal discharge wand to the black grounding post on the Van de Graff machine.
  3. With the machine off, set the speed to about 1/2 speed.

Demonstration Procedure:

  1. Balance the pinwheel on the top of the Van de Graff dome.
  2. Turn the Van de Graff machine on while holding the discharge wand in the other hand.
  3. Note that the Pinwheel starts to rotate. This is because electric fields concentrate at a point, so when the voltage is sufficient, ions will escape off the point into the air. The same charge on the point and the air means 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.