Gold leaf electroscope — Teylers Museum

Gold leaf electroscope

pre 1859

1. An electroscope can demonstrate the existence of an electric charge. Because glass is a good insulator, an electric charge applied to the top side cannot leak away. The charge will spread over the conductive rod. At the bottom side of this rod are two thin gold leafs, which can move easily. Because similar charges repulse each other, these two gold leaves will move apart as soon as the electroscope is charged. This bottle, clad with tin foil at the outside, is an electroscope as designed by A. Bennet (1786). By earthing the tin foil, the electroscope becomes less sensitive to an external electric field. At the bottom is a hygroscopic (water attracting) fluid to absorb any disturbing water vapour.


3. An electroscope is made to establish an electric charge. Its working is based on the repulsion of similar charges. An electric charge applied at the top will spread over the conductor, which causes two thin gold leaves at the inside of the electroscope to move apart. This type, mainly intended for atmospheric electricity, was first described in 1887 by the Austrian natural scientist Franz Exner. Characteristic are the two sideward rods with which two protection plates can be pushed against the gold leaves at the inside. This makes the apparatus easy to transport. This specimen, made by Jilles van Waveren (Teylers Museum's own instrument maker), can be sucked vacuum with an air pump to prevent leaking of charge through the air.