Leyden Jar (condenser)

Invented by : E.G von Kleist

Invented in year : 1745

The Leyden jar or Leiden jar is an electrical device characterized by its capacity to store an electric charge. It stores static electricity between two electrodes on the inside and outside of a jar. The Leyden jar was a very simple device. It consisted of a glass jar, half filled with water and lined inside and out with metal foil. The glass acted as the dielectric, although it was thought for a time that water was the key ingredient. There was usually a metal wire or chain driven through a cork in the top of the jar. The chain was then hooked to something that would deliver a charge, most likely a hand-cranked static generator. Once delivered, the jar would hold two equal but opposite charges in equilibrium until they were connected with a wire, producing a slight spark or shock  The jar was also referred to as a 'Condenser' because many people thought of electricity as fluid or matter that could be condensed. Nowadays electrical terminology terms it as a capacitor.

History

The Leyden jar was first invented by German scientist and jurist, Ewald Georg von Kleist of Camin, Pomerania (10 June 1700 – December 11, 1748). In 1744, he found a method of storing large amounts of electric charge. He lined a glass jar with silver foil, and charged the foil with a friction machine. Kleist was convinced that a substantial charge could be collected when he received a significant shock from the device. On 11 October 1745, he independently invented the Kleistian jar. In Germany, this device was also called 'Kleist's bottle'.  But more commonly, it was known as the Leyden jar, named after Gravesande's graduate student Pieter van Musschenbroek of Leyden. It was several months later, in 1746, when Musschenbroek, became a professor at the University of Leyden that he came up with a very similar device in the form of the Leyden jar, which is typically credited as the first capacitor. It was a device for storing static electricity. In its earliest form it was a glass vial, partly filled with water, the orifice of which was closed by a cork pierced with a wire or nail that dipped into the water. To charge the jar, the exposed end of the wire was brought into contact with a friction device that produced static electricity. When the contact was broken, a charge could be demonstrated by touching the wire with the hand and receiving a shock. In its present form, the inner and outer surfaces of an insulating jar are coated with sheets of metal foil. The outer coating is connected to earth, and a suitable connection is made with the inner coating through a central brass rod that projects through the mouth of the jar.  

Development in the invention of leyden jar

Daniel Gralath was the first to combine several jars in parallel into a battery to increase the total possible stored charge. By the middle of the 19th century, the Leyden jar had become common enough for writers to assume their readers knew of and understood its basic operation. By the early 20th century, improved dielectrics and the need to reduce their size and inductance for use in the new technology of radio caused the Leyden jar to evolve into the modern compact form of capacitor.

Role of the invention of the leyden jar in the improvement of human life

• Before the invention, no one had discovered that electricity could be stored, or generated in any way other than by some friction device.

• In addition to its use for classroom demonstrations, the leyden jar led to the invention of capacitors, which are widely used in radios, television sets and other electrical and electronic equipments.

• Experiments based on leyden jar helped scientists to invent electrostatic generators which facilitated various industries.