This demonstration shows the transfer of charge between a charged plate on the left, an aluminum foil-covered ping pong ball suspended on a thread, and a grounded plate on the right.  As the ball oscillates back and forth between the two plates, it picks up charge, is repelled, loses charge, is attracted – and continues on .

1.  Begin by placing the binding post terminal on top of the Van de Graaff generator sphere—the magnet inside the sphere will hold it in place.  Connect the other end of this wire to the left plate binding post.

2.  Connect the ground wire from the ground binding post on the side of the Van de Graaff generator to the right plate binding post.  You might want to barely push the banana plug into this post so that it easily can be pulled out.

3.  Position the ping pong ball centered between the plates.  The plates should be about 10 cm apart to start with.

4.  Turn on the Van de Graaff generator.  As the charge builds up on the left plate, the ball will be attracted until it touches the plate.  It will then fly off and hit the right (grounded) plate and fly off back to the left plate.  The plates can be moved farther apart (20-30 cm) once the oscillation has been established.

5.  Now pull the ground lead off of the right plate.  What will happen?  Plug it back in.