Electric Charge : Definition, Unit and Properties

What is Electric Charge ?


When a body has deficiency or excess of electrons from the normal due share, it is said to be charged or electrified.

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As we already know from the study of atomic structure that matter is electrical in nature, which means matter contains a large amount of electric charges (protons and electrons).

Under normal condition, the body id electrically neutral as it contains equal amount of positive and negative charges. When this balance is disturbed, by removing or supplying more electrons, the body acquires a net charge. The body will acquire positive charge when electrons are removed from it and acquires  negative charge when electrons are added to it.

Unit of Charge

The charge on an electron is very small so it is not convenient to select it as the unit of charge.

In practice, coulomb (C) is used as the S.I. unit of charge.

One coulomb of charge is equal to the charge on 625 × 1016 electrons.

Hence, the charge on one electron in coulomb is given by;

-e = 1 / (625 × 1016) = -1.6 × 10-19 C

Properties of Electric Charge

The properties of electric charge are as follows :

1. Electric charge is quantized

Electric charge is quantized, that means only certain values of charge are allowed.

Charge on a body Q = ± ne

Where  n = 1,2,3…..

e = -1.6 × 10-19 C

2. Electric charge is a conserved quantity

Electric charge can neither be created nor be destroyed but can be transferred from one body to another by certain methods like conduction and induction.

3. The magnitude of electric charge on a body is independent of the speed of the body
4. Electric charge is a scalar quantity

This means  we can add electrical charges  directly.

Let’s consider a system which consists of two charges namely q1 and q2.  The total charge of the system will be the algebraic sum of q1 and q2 i.e.q1 + q2.

Similarly, for a number of charges q1,q2,q3,q………. qn, in a system, the net charge of the entire system will be equal to q1 + q2 +q3 +q………. + qn.