Electric Charge – Definition, Formula, Unit, Types, and Properties

What is Electric Charge?

The physical property of a substance that causes charged substance to experience a force when placed in an electromagnetic field is called electric charge. In other words, electric charge is the physical property of the subatomic particles of matter due to which matter shows electrical behavior. Electric charge is represented by the symbol Q (or q,).

Electric charge is a conserved property, which means the net charge of a closed remains constant. Electric charge can be of two types namely positive charge and negative charge. The positive charge is the charge carried by protons, while the negative charge is carried by electrons. Therefore, we can say the electric charge is carried by subatomic particles (electrons and protons) of matter. It is experimentally proved that like charges repel each other, and unlike charges attract each other. The substance or body with an absence of net charge is called neutral, i.e. carrying no charge. Hence, when an object consists of an equal number of protons and electrons in its atoms, then it is referred to as neutral.

When the number of electrons are more than that of protons in an object, then the object will have a negative charge. Whereas, if the object consists of less number of electrons than protons, it will have a positive charge.

Electric charge is quantized, which means it always comes in integral multiples of the elementary charge. Where the elementary charge is the amount of electric charge carried by one electron, it is denoted by e and its magnitude is equal to 1.6 × 10^-19 C. This is the smallest charge that can exist freely. The charge on a proton is equal to the elementary charge but is positive.

Formulae of Electric Charge

Electric charge in terms of electronic (or elementary) charge − According to the quantization theory, electric charge is given as the integral multiple of charge on an electron, i.e.

$$\mathrm{Q = ne}$$

Where, n is an integer, and e is the charge on an electron, which is equal to 1.6 × 10^-19 C.

Electric charge in terms of electric current − Electric charge can also be expressed in terms of electric current (I) and time (t) for the current flow through a conductor as,

$$\mathrm{Q = I\times t}$$

Unit of Electric Charge

The standard unit of electric charge in the international system of units (SI) is coulomb, which is represented by the symbol "C". Coulomb is a dimensionless quantity. It may be defined as under −

The quantity of electric charge transferred in one second is called one coulomb. It is approximately equal to charge on 6.24 × 10¹⁸ electrons, i.e.,

$$\mathrm{1\: Coulomb = charge \: on\: 6.24 \times 10^{18}\: electrons}$$

Another unit of electric charge is ampere second (As).

Types of Electric Charge

There are two types of electric charges that exist, namely −

• Positive Charge
• Negative Charge

The electric charge carried by a proton is the positive charge and it travels in the direction of the electric field, while the charge carried by an electron is the negative charge and it moves in a direction opposite to that of the electric field.

Properties of Electric Charge

Various properties of electric charge are given below −

• Like charges repel each and unlike charges attract each other.

• Electric charge is quantized, i.e. there is no fractional charge exists.

• The charge is a conserved property of matter. Therefore, the algebraic sum of charges in any isolated system remains the same.

• Electric charge is a scalar quantity; thus it behaves like a real number during mathematical operations. Thus, electric charge follows the additivity property.

• The electric charge at rest creates an electric field around it. Whereas, the charge in motion creates both an electric field and a magnetic field.

Role of Electric Charge in Electricity

The type of electricity in which the electric charge on an object does not move from one point to another is called static electricity. Static electricity is a result of the accumulation of electric charges on a body. When charges move in a body or conductor, the electricity is referred to as current electricity.

Conclusion

Therefore, in this article, we discussed electric charge which is a subatomic property of matter due to which the matter shows electrical behavior. The electric charge is the fundamental property of all matter in nature. There are two particles namely electrons and protons that carry the electric charge. The electric charge is the main cause behind the existence of electricity and magnetism. Thus, electric charge is used to explain almost all electromagnetic phenomena.