Coulomb's Law

An expression for the electrostatic force between point charges: the force magnitude is proportional to the product of the charges and inversely proportional to the square of their separation, directed along the line joining them (vector form includes unit vector).

In electrostatics (vacuum), the magnitude of the force F between two point charges q1 and q2 separated by distance r is proportional to the product of the charges and inversely proportional to the square of the separation: |F| = (1/(4π ε0))·|q1 q2|/r^2, directed along the line joining them (attractive for opposite signs, repulsive for like signs).