What is an electroscope? Name the two types of electroscope.

Hint: To study electricity, the electroscope was the most popular instrument used by scientists. One can detect if a body is charged or not with an electroscope. But it cannot measure the electric charge quantitatively.

Complete solution:
An Electroscope is a scientific device that one uses to detect whether any electric charge is present on a body. This device also detects the type of charge the body carries, i.e., either positive or negative.
Uses of electroscope –
a) To detect the presence and nature of ionizing radiation on a body
b) To identify and compare the magnitude of charges
c) To calculate the Coulomb force between two charges
The two classical types of electroscopes are –
a) Pith-ball electroscope comprises one or two small-sized balls of non-conducting lightweight substances known as pith.
b) Gold-leaf electroscope – It is made up of a vertical and conductive rod with a metal ball on the top and two thin and parallel gold leaf stripes attached at the bottom.

Additional information:
A pivoted needle, called “Versorium,” was the first electroscope invented by British physicist William Gilbert around $1600$. It detects the charge with the movement of a test object due to the Coulomb electrostatic force on it. This device can give only a rough indication of the quantity of charge.

Note: The amount of charge on an object is proportional to its voltage. We use electroscopes with high voltage sources such as static electricity and electrostatic machines. The reason is the accumulation of enough charge to detect with an electroscope requires hundreds or thousands of volts.