what are the uses of gold leaf electroscope

The gold leaf electroscope has been used by physicists for hundreds of years. It indicates the presence and magnitude of a charge through the application of charge to a copper top plate connected through a stem to two pieces of gold leaf. The movement of one piece of gold leaf away from the other shows that the electroscope is charged. The gold leaf is sealed in a glass case to prevent accidental movement induced by air currents. The stem passes through insulation so that charge cannot escape from the gold leaf