Demo 17-12 Pinwheel

A pinwheel is the electrostatic version of a water sprinkler, as shown in Figure 1, but it works in a very different way. This demonstration is often incorrectly explained using the rocket principle, suggesting that the motion of the pinwheel is a reaction to the motion of the electrons leaving the tips of the pinwheel, much the same as the water sprinkler.Electrons from the generator leave the pinwheel at the points, just as in Demonstrations 17-09 and 17-11 above. This charge then collects on the adjacent air molecules, creating a large cloud of gas charged the same as the tips of the pinwheels. The electrostatic repulsion between the charged tips of the pinwheel and the charged clouds of gas then propels the pinwheel