Coulomb's law or Coulomb's inverse-square law, is a law of physics that describes force interacting between static electrically charged particles. In its scalar form the law is:
{\displaystyle F=k_{e}{\frac {q_{1}q_{2}}{r^{2}}}} {\displaystyle F=k_{e}{\frac {q_{1}q_{2}}{r^{2}}}},
where ke is Coulomb's constant (ke = 8.99×109 N m2 C−2), q1 and q2 are the signed magnitudes of the charges, and the scalar r is the distance between the charges. The force of interaction between the charges is attractive if the charges have opposite signs (i.e. F is negative) and repulsive if like-signed (i.e. F is positive).
The law was first published in 1784 by French physicist Charles Augustin de Coulomb and was essential to the development of the theory of electromagnetism. It is analogous to Isaac Newton's inverse-square law of universal gravitation. Coulomb's law can be used to derive Gauss's law, and vice versa. The law has been tested extensively, and all observations have upheld the law's principle.
