Coulomb's law states that the force between static-electrically-charged objects is proportion to the product of their charges and inversely proportional to the square of their intervening distance:
q1q2 F = ke ———— r²
This is similar to gravitational force, both being inverse square laws, but in this case, the force repels if the charges are the same polarity and attracts if they are opposite polarity. This law and force are equivalent to Gauss's law, one of Maxwell's equations.
The force is relevant to atomic physics, e.g., the attraction between electrons and the nucleus, and nuclear physics, e.g., the repulsion between two nuclei.