Coulomb's law or Coulomb's inverse-square law, is a law of physics describing the electrostatic interaction between electrically charged particles. It was studied and first published in 1783 by French physicist Charles Augustin de Coulomb and was essential to the development of the theory of electromagnetism. Nevertheless, the dependence of the electric force with distance had been proposed previously by Joseph Priestley and the dependence with both distance and charge had been discovered, but not published, by Henry Cavendish, prior to Coulomb's works.

Charles Augustin Coulomb's father was Henry Coulomb and his mother was Catherine Bajet. Both his parents came from families which were well known in their fields. His father's family were important in the legal profession and in the administration of the Languedoc region of France, and his mother's family were also quite wealthy. After being brought up in Angoulême, the capital of Angoumois in southwestern France, Coulomb's family moved to Paris. In Paris he entered the Collège Mazarin, where he received a good classical grounding in language, literature, and philosophy, and he received the best available teaching in mathematics, astronomy, chemistry and botany.

One of them, published in 1785, discussed the inverse square law of forces between two charged particles. This just means that as you move charges apart, the force between them starts to decrease faster and faster (exponentially).

Quantity of charge can be measured in either elementary charges (an elementary charge is the amount of charge on one electron or proton) or in Coulombs.  An elementary charge is a very tiny unit of charge.  Since it is so small it is not usually a convenient unit to measure typical amounts of charge.  It would be similar to measuring distances from one town to the next, in millimeters.  On the other hand, a coulomb is an incredibly large unit of charge.  It is actually too large a unit of charge for talking about electrostatics (stationary charges) but it is an appropriately sized unit as we begin describing the quantity of charge moved in an electric circuit.   Unfortunately, we are stuck with either one unit or the other.  Here is a comparison of the two units:

Coulomb's Law has a variety of applications. It is intended to be used for calculating the force of attraction or repulsion between two charged objects. In reality, however, it is usually more useful to calculate the change in the force of attraction or repulsion between two charged objects than it is to calculate the actual strength of the force of attraction or repulsion. This allows chemists to compare the relative strengths of attractive forces found in bonds or other mechanisms used to hold structures together. Examples of such problems would be as follows.

The electrical interaction between two charged particles is described in terms of the forces exerted between them. Augustin de Coulomb conducted the first quantitative investigation of these forces in 1784. Coulomb used a very sensitive torsion balance to measure the forces between two “point charges,” that is, charged bodies whose dimensions are small compared to the distance between them. Coulomb found that the force grows weaker as the distance between the charges increases, and that it also depends on the amount of charge on each body. More specifically, Coulomb’s force law states that:

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