The Van de Graff Generator
The Van de Graff generator uses friction between a rubber belt and plastic roller to produce large amounts of charge. The rubber belt carries the charge to the inner surface of the spherical metal cap. Charge on the cap will be repelled by the accumulated charge and collect on the outside surface of the cap
A Van de Graff generator can produce voltages of up to 10,000,000 V. These can be used in physics to accelerate charged particles for use in particle physics experiments or used to investigate static electricity. If an insulating ball is brought close to the generator, some charge will distribute within the molecules of the ball. The net effect will be a net attraction of the ball to the generator. If a conducting ball is brought close to the sphere and grounded, charge may pass from the generator to the sphere in the form of a spark.