Electrostatic Charge on a Hollow Cylinder

Demonstration of charge induction. The positive terminal of an electrostatic machine is placed near the right end an uncharged brass cylinder, causing the left end to acquire a positive charge and the right to acquire a negative charge. The the charge is concentrated at the ends. The pith balls will both be repelled from the cylinder ends, but a proof plane and an electroscope can be used to verify that they have opposite charges.