Leyden jar

In a Leyden jar, an electric charge can be stored for a while. Its invention was revolutionary, because various new experiments could be carried out because of this new storage. The Leyden jar is named after the residence of the physicist Pieter van Musschenbroek, who was the first to publish about it in 1746. The story goes that he invented the jar when he tried to electrify water. In his experiment, Van Musschenbroek filled a jar with water and passed a metal rod through the cork. He connected this rod with an electrostatic generator, which generates static electricity. When he touched, with the jar in one hand, the metal rod with his other hand, he got an enormous shock. It was so enormous, that Pieter wrote to a colleague that he never again wanted to repeat the experiment. Soon after, the Leyden jar as we know it now, was made. The inside as well as the outside are covered with metal foil. Because glass is not conductive, it acts as an isolator. At the top of the jar is a spherical electrode which is connected to the metal foil at the inside (sometimes, some iron filings are put in the jar too). Charge can be taken away or added via the sphere.