(Wikipedia excerpt:.. “…The electroscope (E) is an early scientific instrument used to detect the presence of electric charge on a body. It detects charge by the movement of a test object due to the Coulomb electrostatic force on it. The amount of charge on an object is proportional to its voltage. The accumulation of enough charge to detect with an electroscope requires hundreds or thousands of volts, so (E) are used with high voltage sources such as static electricity and electrostatic machines. An (E) can only give a rough indication of the quantity of charge; an instrument that measures electric charge quantitatively is called an electrometer.
The (E) was the first electrical measuring instrument. The first (E) was a pivoted needle (called the versorium), invented by British physician William Gilbert around 1600. The pith-ball (E) and the gold-leaf (E) are two classical types of (E) that are still used in physics education to demonstrate the principles of electrostatics. A type of (E) is also used in the quartz fiber radiation dosimeter. (E) were used by the Austrian scientist Victor Hess in the discovery of cosmic rays. …’)