Induction, Electric, is the process by which an electrically charged object charges another object without touching it. Such induction is caused by electrostatic attraction, the attraction that opposite electrical charges have for each other. Electric induction should not be confused with electromagnetic induction or inductance, which deal with magnetic fields.
Electric induction can be used to charge a metal object supported by an insulator. For example, a glass rod rubbed with silk will become positively charged. If it is brought near—but does not touch—the insulated metal object, the rod pulls electrons in the metal to the side of the object nearest the rod. The opposite side of the object then lacks electrons, and so has a positive charge. If the opposite side is momentarily connected to the ground—which has a large supply of electrons—additional electrons will flow into the object. This flow occurs because electrons are attracted to the positive charge on that side. Removing the ground connection and then removing the rod causes the metal object to retain the excess negative charge it received by induction.
The Van de Graaff generator is a machine that uses electric induction. In it, a moving insulating belt charges a hollow metal dome to many million volts. This high voltage is used to accelerate charged particles used in nuclear and particle physics experiments.
