Electrophorus Plate

This is a large plate of a record or plexiglass that becomes strongly charged when rubbed with silk. If a disk-shape metal plate with an insulating handle is placed on the charged plate, the face becomes negatively charged by induction while the back side acquires the same charge as the charged plate. If you now touch the metal plate, thus conducting away the charge on the back, and then remove the plate by the handle, it will have net negative charge that can be checked by touching a electroscope with the plate.