An apparatus for generating static electricity, consisting of a hard rubber disk that is given a negative charge by friction and a metal plate that is given a net positive charge by induction when in contact with the disk.
Italian scientist Alexander Volta in 1775 gave the electrophorus the form which it retains to the present day.
I first excite the electrophorus in the usual manner, and you see that it then influences a charge in its top plate; the charge in the resinous compound is known as negative, while the charge induced in its top plate is known as positive.
These tiny sparks from the electrophorus, or the bigger discharges of an electrical machine, can be stored in a simple apparatus called a Leyden jar, which was discovered by accident.
The word 'electrophorus' comes from Greek roots meaning 'amber' and 'to bear'. Amber, when rubbed, produces static electricity.