Coulomb's Law

The magnitude of the force between two point charges $q_{1}$ and $q_{2}$ with distance $r$ is equal to the following

F_{q_{1}, q_{2}} = \frac{1}{4 π ϵ _{0}} \frac{∣ q _{1} \cdot q _{2} ∣}{r ^{2}} = k \frac{∣ q _{1} \cdot q _{2} ∣}{r ^{2}}

Notes