Question

What is Leyden jar? How does it work?

Answer 1

A Leyden jar is a device that stores static electricity between two electrodes on the inside and outside of a glass jar. A Leyden jar typically consists of a glass jar with metal foil cemented to the inside and the outside surfaces, and a metal terminal projecting vertically through the jar lid to make contact with the inner foil. It was the original form of a capacitor (originally known as a "condenser").
A typical design consists of a glass jar with conducting tin-foil coating the inner and outer surfaces. The foil coatings stop short of the mouth of the jar, to prevent the charge from arcing between the foils. A metal rod electrode projects through the stopper at the mouth of the jar, electrically connected by some means (usually a hanging chain) to the inner foil, to allow it to be charged. The jar is charged by an electrostatic generator, or another source of electric charge, connected to the inner electrode while the outer foil is grounded. The inner and outer surfaces of the jar store equal but opposite charges. It takes energy to move additional charges to the jar as the charges overcome the repulsive forces of the charges already on the conductors. The jar stores this electrical energy. If the inner and outer conductors are connected by a wire the charges flow and make the two conductors neutral again.