Induced Charge

An induced charge is a charge that “appears” on an uncharged object because of a charged object nearby.
The induced charged always has the opposite charge to the inducing charge. Charges can only be induced when charges are free to move to some extent, because for example, they are in a conductor.

A charge can be induced by rubbing a plastic rod on fabric. It will gain some electrons and become negatively charge. Bringing it close to a conducting metal sphere on an insulating base will negative charges - electrons - to be repelled. One side of the sphere will be positively charged, and one side negative as the electrons move. If the negative side is earthed, electrons can flow to earth. Removing the charge rod will leave the sphere with a net positive charge due the loss of electrons.