Electric Charge

What is Electric Charge?

Atoms are the constituents of matter. Atoms are electrically neutral because the number of electrons is equal to the number of protons. Protons do carry a positive charge, whereas electrons have an equal negative charge. Photos are located in the central part of an atom, called a nucleus, along with the electrically neutral neutrons. Protons are bounded with the nucleus.


An electron carries a negative charge and revolves around the nucleus in a definite orbit. The magnitude of electric charge of an electron and a proton are equal but are opposite in nature. Typically, the matter is electrically neutral because it is made up of electrically neutral particles or atoms.


Electric Charge Definition

Just like protons, the electrons are also bound in an atom, but not all electrons. The electrons which are located farther from the nucleus can be removed from the atom. When some electrons are removed from the atom, the number of protons becomes higher than the number of electrons due to a deficit in electrons. After the removal of electrons, the electrically neutral body becomes positively charged.

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In the opposite case, the body can also acquire electrons from an outside source. In this case, the number of electrons in the body increases, and it becomes negatively charged. 

The deficit or surplus of electrons in a body is called an electric charge.


Unit of Electric Charge

The matter is always positively charged, negatively charged, or neutrally charged. A charge is denoted by 'q', and the SI unit of electric charge is Coulomb. The charge of a particle is basically the cumulative charges of all the electrons present in it. Mathematically it is represented as

Q = ne

where,

q = charge,

n = number of electrons, and

e = charge on 1 electron which is 1.6 × 10-19C. This is the  electric charge value on an electron. The two basic natures of electric charge are

  • Like charges repel each other.

  • Unlike charges, they attract each other.


This means that the protons repel protons, while they attract electrons. Similarly, the electrons repel electrons, and they attract protons. The forces acting on a charge are directly associated with the nature of the charge. The magnitude of the charge on an electron and a proton is the same, and it is 1.6 × 10-19C. The charge on an electron is negative '-', will the charge on a proton is positive '+'.


How is Electric Charge Measured?

Electric charge is measured in the unit of Coulomb. A charge is said to be 1 coulomb when a current of 1 ampere flows through a unit cross-sectional area for one second. The electric charge formula is given by:

Q = I.t

Where,

  • Q = electric charge

  • I = electric current

  • t = time.


Basic Properties of Electric Charge

There are a large number of properties of electric charge. Some of the basic properties of the electric charge are mentioned below.

  • Electric charge is additive in nature.

  • An electric charge is a conserved quantity.

  • Electric charge can be quantized.

  • Due to the presence of an electric charge, a body either attracts or repels another body based on the nature of charge.

  • Friction between two different types of objects produces a positive charge on one object and a negative charge in another object. When the glass is rubbed with plastic, the glass gains excess electrons and becomes negatively charged, whereas the plastic loses electrons and becomes positively charged.

  • Like charges repel each other, i.e., positive charges repel positive charges and negative charges repel negative charges.

  • Unlike charges attract each other, i.e., positive and negative charges attract each other.

  • Repulsion is the sure test to determine the nature of a charge on a body.


What is a Positive and a Negative Charge?

There are two types of charge, these are:

  • Positive Charge

  • Negative Charge


Positive Charge

When an object loses some electrons, the number of protons in the object becomes greater than the number of electrons. Hence, the object becomes positively charged.


Negative Charge

When an object gains some electrons, the number of electrons in the object becomes greater than the number of protons, and hence it becomes negatively charged.

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FAQ (Frequently Asked Questions)

1. Give some Electric Charge Examples.

Ans During cloudy weather, lightning occurs due to the presence of a large amount of electric charge in the clouds. This suggests that the things around us also carry an electric charge stored in them.


The electrically neutral objects consist of a large number of positive and negative charges that cancel out each other, and therefore no external effects occur. A body is said to be charged, when it has a charge imbalance in its constituent particles, although it may be a short amount of charge.


When objects are charged, they exert some force on each other. For example, when a glass rod is rubbed with silk, the electrons from the glass are transferred to silk. This results in a positive charge to develop in the glass. Similarly, when silk acquires electrons, it becomes negatively charged.

2. How are Charges Produced?

Ans When we rub a plastic comb through our hair, and after this, if we bring small pieces of paper near the comb, it starts to attract the paper. Similarly, when amber is rubbed with silk, it also starts to attract pieces of paper. These attractions and repulsions are developed in a substance because it acquires some charge.

Electric charge can be produced by rubbing one neutral object with another neutral object. Two different kinds of charges are developed on the two different objects. An object becomes positively charged while the other becomes negatively charged.

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Let us consider an example. First, we have to rub a plastic rod with fur and then suspend it horizontally using a silk thread as per the diagram. Now, if we rub another plastic rod with fur and bring it near the suspended rod, we'll notice that both the rods repel each other. This is due to the presence of a similar charge.

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Now, if we take a glass rod and rub it with silk and then suspend it horizontally, now we rub a plastic rod with fur and bring it near the suspended rod, we'll observe that the rods attract each other. This is due to the presence of the opposite charge.

The process of rubbing develops positive and negative charges.