A gold-leaf electroscope is a sensitive instrument that is used to detect an electric charge. It is made up of a brass rod with a brass disc attached at the top and two thin gold leaves in the shape of foils at the bottom.
The rod goes through the insulator to hold itself in place as shown in the figure below.
Step 2: Charge detection
The object that has to be tested is connected with the metal cap to detect charge. If the leaves of the electroscope diverge, the body is said to be charged; if there is no movement in the leaves of the electroscope, the body is said to be uncharged.
Consider an example to determine the nature of the charge. A positively charged body is brought in close proximity to the metal cap. Then an unknown body is moved close to the metal top. If the leaves continue to diverge, we can deduce that the unknown body is positively charged. The unknown body's charge will be negative if the leaves come closer together.
Two gold-leaf electroscopes are used to determine if a body is a conductor or an insulator. One gold leaf electroscope is charged, causing the leaves to diverge. The second gold leaf electroscope is then connected to the first. If the leaves of the other electroscope diverge, the body is a conductor; if the leaves don't show any movement, then the body is said to be an insulator.
