How are electric forces and charge related?

The force between to point charges is calculated by :

• ##F = (kQ_1Q_2)/(r^2)## where ##Q_1## and ##Q_2## are the two charges in coulombs, k is the Coulomb constant (##8.9875 times 10^9 (N*m^2)/(C^2)## ) , and r is the distance between the centers of the two charges in meters.

One charge creates an electric field throughout all of space, and it is the interaction with this field that causes the force on the second charge.