Leyden jar

Leyden Jar

The Leyden jar is a device that "stores" static electricity between two electrodes on the inside and outside of a glass jar. It was the first form of a capacitor. It was invented independently by German cleric Ewald Georg von Kleist on 11th October 1745 and by Dutch scientist Pieter van Musschenbroek of Leiden University in 1745–1746, hence the name 'Leyden jar'.

History

The Leyden jar was invented in the context of investigations into electricity in the mid 18th century. The discovery was made independently by two parties: Ewald Georg von Kleist, a German cleric, and Pieter van Musschenbroek, a scientist from the Netherlands. The device was named after the city of Leiden where Musschenbroek worked, although Kleist was the first to develop the concept.

Design and Function

The Leyden jar consists of a glass jar with metal foil cemented to the inside and the outside surfaces, leaving a space at the mouth to prevent arcing between the foils. The original form of the device was just a glass bottle partially filled with water, with a metal wire passing through a cork closing it. The role of the outer plate is to isolate the inner plate electrically, which makes it an example of a capacitor.

When a charged object touches the metal insert, it induces an equal and opposite charge in the body of the jar. This induced charge can be discharged by providing a path to the insert for it to flow back. This discharge, or the movement of the induced charge back to the insert, can produce a significant electrical current for a short time.

Applications

The Leyden jar was used in early experiments in electricity to store electrical charge for use in experiments. In the years following its invention, the Leyden jar was used to conduct many experiments that revealed the principles of electricity. Today, while Leyden jars are primarily used for educational purposes, the principles they use are applied in the capacitors used in many electrical and electronic devices.

See Also

• Capacitor
• Ewald Georg von Kleist
• Pieter van Musschenbroek
• Electricity