Question

What is the procedure to measure charge in a body using an electroscope?

Answer 1

Hint:We know that the electroscope detects the charge according to the fact that coulomb electrostatic force causes the motion of test charge. The working of an electroscope is dependent on the atomic structure of elements, charge induction and the internal structure of metal elements. It mainly works on the concept of attraction and repulsion of charges.

Complete answer:
To understand the procedure to measure a charge in a body using electroscope, let us first understand the construction of the electroscope. Is made of a metal detector knob on top which is connected to a pair of metal leaves hanging from the bottom of the connecting rod. When there is an absence of charge, the metals leaves hang loosely in direction. However, when an object with a charge is brought near an electroscope, there are two possible cases.

First, let us consider that the charge is positive. In this case, electrons in the metal of the electroscope are attracted to the charge and move upward out of the leaves. Due to this, the leaves tend to have a temporary positive charge and because of the act that like charges repel, the leaves separate. Then once the charge is removed, the electrons return to their original positions and the leaves relax.

In the second case, when the charge is negative, the electrons in the metal of the electroscope repel and move toward the leaves on the bottom. Because of this, the leaves gain a temporary negative charge and as charges repel, the leaves again separate. After the charge is removed, the electrons return to their original position and the leaves relax.

Note:As we have seen in this question, an electroscope responds to the presence of a charge through the movement of electrons either towards or away from the leaves. In both these cases, the leaves separate. It is important to keep in mind that the electroscope cannot find whether the charged object is positive or negative. Its only work is to respond to the presence of an electrical charge.