The electrophorus is an instrument invented in 1775 by Italian physicist Alessandro Volta (1745–1827) for producing an electrical charge that could be transferred to other objects. A pewter disc, held by an insulating glass handle coated with sealing wax, was combined with a well-polished resin plate that had been rubbed with a piece of fur, which had the effect of giving it a negative charge. When the metal disc is placed on the latter, the surface in contact with the resin becomes positively charged by induction, whereas the surface in contact with the handle acquires a negative charge. If the upper surface of the disc is touched with a finger and thus earthed before it is taken off the resin, the pewter remains positively charged (whereas the resin is negative). This constitutes a source of electrical charge that can be used to charge other bodies.

Device on display.