Coulomb's Law quantifies the electrostatic force between two charged objects. The force is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
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Coulomb's Law formula is $F = k \frac{q_1 q_2}{r^2}$, where $F$ is the electrostatic force, $k$ is Coulomb's constant ($8.99 \times 10^9 \text{Nm}^2/\text{C}^2$), $q_1$ and $q_2$ are the charges, and $r$ is the distance between them.
The direction of the force depends on the signs of the charges: like charges repel and opposite charges attract.
Coulomb's Law applies to point charges or spherically symmetric charge distributions.
The law assumes that other forces (e.g., gravitational) are negligible compared to electrostatic forces in most practical scenarios.
In a vacuum, Coulomb's constant ($k$) has a value determined by the permittivity of free space ($\epsilon_0$), where $k = \frac{1}{4\pi\epsilon_0}$.
Review Questions
What is the mathematical expression for Coulomb’s Law?
How does Coulomb’s Law describe the relationship between force and distance?
What happens to the electrostatic force when both charges are doubled?
$\epsilon_0$, also known as permittivity of free space, is a constant representing how much resistance is encountered when forming an electric field in a vacuum.