Electric fleas

Rub a long-playing record with a woolen cloth and place it on a glass. If you toss some small silver-paper balls on to the record, they will jump away from one another in a zigzag motion.

If you then move the balls together with your fingers, they will hop fiercely away again.

The electricity produced on the record by rubbing is distributed in irregular fields. The balls take up the charge and are repelled, but are again attracted to fields with the opposite charge. They will also be repelled when they meet balls with the same charge.