NCERT · Class 12 · Physics · Electric Charges and FieldsState Coulomb's law in electrostatics and write its mathematical formula.

Coulomb's law states that the electrostatic force of attraction or repulsion between two stationary point charges is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them. Mathematically, $F = k \frac{|q_1 q_2|}{r^2}$, where $k = \frac{1}{4\pi\varepsilon_0} \approx 9 \times 10^9\text{ N}\cdot\text{m}^2/\text{C}^2$ in free space, $q_1$ and $q_2$ are charges, and $r$ is the separation distance.