Electric Charge: Definition, Types, SI Unit, Formula and Properties

Electric Charge is all around us, even though we cannot see it directly. From a spark produced when removing a sweater to lightning flashing across the sky, many everyday events happen because of electric charge. It is one of the basic properties of matter that helps explain how electrical devices and natural phenomena work. Have you ever rubbed a balloon on your hair and noticed it sticking to a wall? Or felt a small shock after touching a metal object? These simple experiences are connected to electric charge. The movement and interaction of charged particles make many electrical effects possible. This article mainly focuses on what is electric charge, its types, the SI unit, the formula, and important properties.

Table of Contents

• What is Electric Charge
• Different Types of Electric Charge
• Properties of Electric Charge
• Important Methods of Charging

What is Electric Charge 

Electric charge is a basic property of matter that causes objects to experience electrical forces. Some particles attract each other, while others repel. This behavior happens because of the electric charge.

The important fact is that every object around us contains charged particles. These charges are responsible for many electrical and magnetic effects that we observe daily.

Electric charge can be defined as the physical property of a particle that causes it to experience a force when placed in an electric or magnetic field.

In simple words, electric charge is the property that allows particles to attract or repel one another. The symbol used for electric charge is Q. 

But what is the SI unit of electric charge? The SI unit of electric charge is theCoulomb (C). One coulomb is the amount of charge transferred by a current of one ampere in one second. The SI unit is named after the French physicist Charles-Augustin de Coulomb, who studied electric forces between charged objects.

Moving ahead, let’s look at the formula used to calculate electric charge.

Q = I t

Where Q is the electric charge, I is the electric current, and t is the time taken.

Have you ever heard about scalar and vector quantities? A scalar quantity has only magnitude, while a vector quantity has both magnitude and direction. Electric charge is a scalar quantity. But why is the electric charge considered scalar? It is because charges add algebraically and do not follow vector addition rules. Therefore, electric charge has magnitude only.

Different Types of Electric Charge

Electric charge is not the same in all objects. It exists in two types: positive charge and negative charge. Let's learn about them. 

Positive Charge

A positive charge is associated with protons present inside the nucleus of an atom. Examples:

• Glass rod rubbed with silk
• Protons inside atoms

Negative Charge

Negative charge is associated with electrons that move around the nucleus. Examples:

• Plastic comb rubbed on dry hair
• Electrons in atoms

Interaction Between Charges

Type of Charges	Result
Positive and Positive	Repel
Negative and Negative	Repel
Positive and Negative	Attract

Do you know? The attraction between opposite charges is the reason many electrical devices work properly.

Important Properties of Electric Charge

Just like other physical quantities, electric charge has some important properties. These properties help us understand how electric charges behave in different situations.

Additivity of Charge

When multiple charges are present together, the total charge is the algebraic sum of all individual charges.

For example:

• +4 C + (+2 C) = +6 C
• +4 C + (-2 C) = +2 C

So, in simple words, charges can be added or subtracted based on their signs.

Conservation of Charge

The law of conservation of charge states that charge can neither be created nor destroyed.

It can only be transferred from one object to another.

Imagine transferring water from one bottle to another. The amount of water remains the same. Similarly, charge is conserved.

Quantization of Charge

Electric charge exists in fixed packets called elementary charges. The charge of an electron is, 1.6 \times 10^{-19} C

Any charge found in nature is a whole-number multiple of this elementary charge. Interestingly, charge cannot exist in arbitrary amounts.

Different Methods of Charging

Objects can gain or lose electric charge through different methods.

Charging by Friction

When two objects are rubbed together, electrons transfer from one object to another. Examples,

• Rubbing a balloon on hair
• Rubbing a glass rod with silk

One object becomes positively charged, while the other becomes negatively charged. Charging by Conduction

In this method, a charged object touches an uncharged object. As a result, electrons move between them, and the uncharged object gains charge.

Charging by Induction

Charging by induction occurs without direct contact. When a charged object is brought near a neutral object, charges inside the neutral object rearrange themselves.

This process causes the object to become charged.

Till now, we have learned that electric charge is a basic property of matter that causes attraction and repulsion between particles. We also understood its types, SI unit, formula, important properties, and different methods of charging. Electric charge plays a key role in many natural events and modern technologies, making it one of the fundamental concepts in physics.