Electric Charge is one of the important concepts in electrical engineering. This article is meant to explain the electric charge definition, types, unit, properties, and formula. In short, electric charge can be defined as a physical property of a material that causes it to experience forces when placed in an electromagnetic field.
Electric Charge Definition
Electric Charge is the fundamental property of subatomic particles of materials that causes it to experience attraction or repulsion forces when placed in an electromagnetic field.
In materials, electric charges are carried by electrons and protons, which are nothing but subatomic particles of matter.
Electric charge is generally represented by using symbols Q or q.
Types of Electric Charge
Electric charges can be classified into the following two types –
- Positive Charge – Positive charge (+ve charge) can be defined as the charge that experiences a repulsive force when placed in a positive electric field and experiences a force of attraction when placed in a negative electric field. Positive charge is carried by protons.
- Negative Charge – A negative charge is one that experiences a repulsive force when it is placed in a negative electric field and experiences a force of attraction when placed in a positive electric field. Negative charge is carried by electrons.
Unit of Electric Charge
The SI unit of electric charge is the Coulomb, denoted by C. The unit of electric charge Coulomb, is given to honor the research work of George Simon Ohm (Ohm’s Law).
Charge on an Electron
As we know, an electron is a negative charge carrier and it carries an electric charge of magnitude,
$$Q_e=-1.6×10^{-19}\text{ C}$$
In general, the electronic charge is denoted by “e”.
Similar to an electron, the charge carried by a proton is denoted by Qp, and it is equal to,
$$Q_p=+1.6×10^{-19}\text{ C}$$
Electric Charge Formula
Electric charge is a quantized quantity, and it is given as an integer multiple of elementary charge (e), i.e.
q = ne
Where n = 1, 2, 3, 4,…
Therefore, the number of electrons constituting 1 coulomb of charge is,
$$n=\frac{q}{e}=\frac{1}{1.6×10^{-19}}$$
$$∴n=6.24×10^{18}\text{ electrons}$$
Properties of Electric Charge
Electric charge has the following three key properties –
- Like (same) charges repel each other, i.e., negative-negative charges or positive-positive charges repel each other.
- Unlike (dissimilar) charges attract each other, i.e., negative-positive charges attract each other.
- Conservation of charge – Electric charge is a conserved quantity. Hence, charge can neither be created nor destroyed. The total charge of an isolated system remains constant.
Important Concepts Related to Electric Charge
The following are some key points to remember about electric charge –
- Electric charge is the most fundamental quantity in an electric circuit.
- Charge can be defined as the electrical property of the atomic particle of which matter consists of.
- The SI unit of electric charge is Coulomb, denoted by C.
- From basic physics, we know that atoms are the fundamental building blocks of all matters.
- Each atom consists of a certain number of electrons, protons, and neutrons.
- The charge on an electron is negative and has a magnitude of 1.6 x 10-19 C.
- The charge on a proton is positive and has a magnitude equals 1.6 x 10-19 C, i.e. same as the electron.
- When an atom has equal number of electrons and protons, it will be neutrally charged.
- Coulomb is a very large unit of charge, as it equivalent to 1/1.6×10-19 = 6.24×1018 electrons.
- By experimental observations, it has been observed that electric charges exist in nature as the integral multiples of the charge on an electron.
Law of Conservation of Charge
According to the law of conservation of charge, the electric charge can neither be created nor destroyed. It can only be transferred.
Therefore, the algebraic sum of electric charge in a system remains constant, or we can say does not change.
Conclusion
Hence, this is all about electric charge and its definition, formula, unit, and properties. In conclusion, electric charge is an invisible physical characteristic of matter, but it is entirely responsible for the existence of electricity.