Electric Charge
Understanding electric charge and its fundamental properties.
What is Electric Charge?
Electric charge is a fundamental property of matter that causes it to experience a force when placed in an electromagnetic field. It is carried by subatomic particles, primarily electrons (negative charge) and protons (positive charge).
Properties of Electric Charge
- Two Types: Positive and Negative. Like charges repel, and opposite charges attract.
- Quantized: Electric charge exists in discrete units, multiples of the elementary charge (e), which is the magnitude of the charge of an electron or proton.
- Conserved: In an isolated system, the total electric charge remains constant. Charge cannot be created or destroyed, only transferred.
Units of Electric Charge
| Unit | Symbol | Description |
|---|---|---|
| Coulomb | C | The SI unit of electric charge. One Coulomb is approximately 6.242 × 10^18 elementary charges. |
| Elementary Charge | e | The magnitude of the charge of a single electron or proton (approx. 1.602 × 10^-19 C). |
Coulomb's Law
Coulomb's Law describes the electrostatic force between two charged particles. It states that the force is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them.
Where:
• F = Electrostatic force
• k = Coulomb's constant (approx. 8.9875 × 10^9 N·m²/C²)
• q1, q2 = Magnitudes of the charges
• r = Distance between the charges
Frequently Asked Questions
What is the difference between charge and current?
Charge is a fundamental property of matter, while current is the rate of flow of electric charge. Current is measured in Amperes (A), where 1 Ampere is 1 Coulomb per second (1 A = 1 C/s).
Can charge be fractional?
While elementary charges (electrons and protons) are considered the smallest indivisible units of charge, quarks (which make up protons and neutrons) have fractional elementary charges (e.g., ±1/3e, ±2/3e). However, quarks are not observed in isolation.