Stephen Gray (English) discovered electrical conductors in 1729 and Charles Dufay (French) first expressed the idea of a repulsive electric force in 1733. Ben Franklin (Colonial American Statesman) was the first to use "+" and "-" for the two types of electric force, attraction (positive) and repulsion (negative). He espoused the law of conservation of charge within a region.
In 1745 the Leyden jar, the first capacitor, was discovered by Ewald Georg von Kleist, a German inventor. A Dutch physicist Pieter van Musschenbroek of the University of Leyden also discovered the Leyden jar independently in 1746.
The first Leyden jar was a glass jar partially filled with water and stoppered with a cork that had a wire inserted through the center of it that dipped into the water. The wire is brought into contact with a static electricity producer and the jar is thus charged. A conductor that comes into contact with or comes close to the wire will discharge the Leyden jar.
Currently, the Leyden jar is a glass jar with a metal foil coating on the inside and the outside. A metal rod is passed through an insulating stopper in the mouth of the jar and is brought into contact with the inside foil coating. The Leyden jar is charged by charging the inside coating either positively or negatively and charging the outside coating with the opposite charge simultaneously. If the two coatings are connected by a conductor, the jar will discharge.
Updated: 24 March 2000
Publisher: Tyra BuczkowskiCopyright © 1996-2002 Tyra T. Buczkowski. All rights reserved.