The coulomb formula you'll see most often in the study of physics is Coulomb's law.

This law refers to the relationship between force, charge, and distance between particles.

### The Equation

The law states that the force (F) between two charges is equal to Coulomb's constant (represented as a lowercase k) multiplied by the two charges as coulombs (q1 and q2) divided by the square of the distance between the two charges (r).

This can be confusing when explained with words, so let's look at the formula:

#### F = k * ((q1*q2) / r^{2})

Coulomb's constant (k) is equal to 9 e^{9} N·m^{2} C^{-2}.

Both q1 and q2 should be in Coulombs (C) and the distance measured in meters (m).

This allows all the units to cancel properly to leave you with Newtons, giving you the answer as a unit of force.

### Interpreting The Resulting Force

When the resulting force is a positive number (+F) that means that the force between the two charged objects is attractive.

When the resulting force is a negative number (-F) that means that the force between the two charged objects is repulsive.

This equation is used in many parts of physics, especially the study of electricity and magnetism.