The electrophorus is a device for supplying charge and charging insulated conductors to a large potential. The basic operational steps for the electrophorus are depicted in the sequence of diagrams below.
The steps are:
A ebonite slab is charged by rubbing with fur so that it becomes charged (negatively in this case).and an insulated brass disc brought close to it. The disc will acquire an induced charge, positive at the bottom and negative above.
The disc is brought into contact with the ebonite slab.
The upper side of the dis brass disc is earthed, so that it is left with a positive charge.
The disc is removed from the slab. It is positively charged. The electrostatic energy produced is a result of the work done to separate the disc from the slab, since they are oppositely charged and attract each other.