Coulomb's law (C. de Coulomb)
The primary law for electrostatics is analogues to Newton's law of universal gravitation. This states that the force among two point charges is proportional to the algebraic product of their respective charges in addition to proportional to the inverse square of the distance among them; mathematically specking,
F = 1/(4 pi epsilon0) (q Q/r2) e,
where q and Q refer to the strengths of the two charges, r refer the distance among the two, and e refer to a unit vector directed from the test charge to the second.