What is a gold leaf electroscope?
The basic construction consists of an earthed metal box with glass windows, as shown in the figure.
A gold leaf is attached to one end of the metal rod. On the other end of the rod there is a metallic cap. When the cap is touched with a charged object, the charge flows down through the metal rod to the gold leaf. Charge will be distributed in the gold leaf and the lower end of the metal rod. The repulsive force between similar charges causes the gold-leaf to be deflected from the end of the rod.