What is Electric Charge?
Electric charge is one of the fundamental properties of matter. Every electrical and electronic circuit works because of the movement and interaction of electric charges. Understanding electric charge helps us understand voltage, current and the operation of electronic components.
What is Electric Charge?
Electric charge is a physical property of matter that causes objects to experience electrical forces. Objects may have either a positive charge or a negative charge.
Charges of the same type repel each other, while opposite charges attract.
The Structure of an Atom
Everything around us is made of atoms. Each atom contains three basic particles.
| Particle | Charge | Location |
|---|---|---|
| Proton | Positive (+) | Inside the nucleus |
| Neutron | No charge | Inside the nucleus |
| Electron | Negative (−) | Orbiting the nucleus |
In electrical circuits, it is the movement of electrons that produces electric current.
Positive and Negative Charges
There are two kinds of electric charge.
- Positive charge is carried by protons.
- Negative charge is carried by electrons.
Normally, an atom contains the same number of protons and electrons, making it electrically neutral.
If an atom gains extra electrons, it becomes negatively charged. If it loses electrons, it becomes positively charged.
How Electric Charge is Measured
Electric charge is measured in a unit called the coulomb (C).
One coulomb represents an enormous number of electrons.
Approximately:
1 C ≈ 6.24 × 1018 electrons
Because this number is so large, electronic circuits usually involve much smaller quantities of charge.
Conservation of Charge
Electric charge cannot be created or destroyed. It can only be transferred from one object to another.
For example:
- Rubbing a balloon on your hair transfers electrons.
- Charging a battery transfers electrical charge through chemical reactions.
- Charging a capacitor stores electric charge.
Electric Charge and Current
When electric charges remain stationary, they create static electricity.
When charges move continuously through a conductor, they produce electric current.
This flow of charge powers electrical and electronic devices.
Examples of Electric Charge
- Lightning is caused by the movement of huge amounts of electric charge.
- A battery stores electric charge chemically.
- Capacitors temporarily store electric charge.
- Touching a metal object after walking on a carpet may discharge static electricity.
Why Electric Charge is Important
Understanding electric charge makes it easier to understand:
- Voltage
- Electric current
- Capacitance
- Electric fields
- Electronic components
- Semiconductors
Nearly every topic in electronics begins with understanding electric charge.
Key Points
- Electric charge is a basic property of matter.
- There are two types of charge: positive and negative.
- Electrons carry negative charge.
- Protons carry positive charge.
- Like charges repel; opposite charges attract.
- Charge is measured in coulombs (C).
- Moving electric charge produces electric current.