Charging by conduction involves the contact of a charged object to a neutral object. .
Explanation:
Suppose that a charged aluminum plate is touched to a neutral metal sphere, the neutral metal sphere becomes negatively charged because of the results of being contacted by the charged aluminum plate.
A charged metal sphere is touched to the highest plate of a neutral needle measuring instrument, the neutral measuring instrument becomes charged because of the results of being contacted by the metal sphere.
For example, a student standing on an insulating platform touches a negatively charged Van de Graaff generator, the neutrally charged student becomes charged. This is due to the contact made with the Van De Graaff generator which is negatively charged.
