How does Coulomb’s law describe the force between two charged objects?

Coulomb’s law provides a mathematical description of the electric force between two charged objects at rest. The law establishes several key properties of this interaction:

• Direction: The force acts along the straight line connecting the two charges. Like charges (both positive or both negative) repel each other, while unlike charges (one positive and one negative) attract each other.12
• Magnitude: The size of the force is directly proportional to the product of the magnitudes of the two charges ($q_1$ and $q_2$) and inversely proportional to the square of the distance ($r$) between them.12
• Mathematical Representation: In the SI system, the force is expressed as $F=k\frac{q_1{q}_2}{r^2}$, where $k$ is the proportionality constant (approximately $8.99\times {10}^9{\text{ Nm}}^2/{\text{C}}^2$ in a vacuum).32

Because the force is a vector, it possesses both magnitude and direction. Fundamentally, this force arises because each charge creates an electric field that exerts a force on the other charge located within that field.34