Coulomb's Law Definition

In physics, coulomb's law is defined as the force of repulsion or attraction among the points of two charges that are directly proportional to the multiplicative product of the charge's magnitudes and inversely proportional to the distance of square between the charges. For instance, in ancient times, the tribes living around the Mediterranean Sea used a technique that defines coulomb's law. To attract or catch lighter objects like feathers, they rubbed a rod of amber on a cat's fur so that the force of attraction is caused by the points of two charges.


Table of Contents

Formula of Coulomb's Law

The formula used for coulomb's law is listed below:

\[F = K(\frac{{{q_1}\;.\;{q_2}}}{{{{\rm{r}}^2}}})\]


F = Electrostatic attraction or repulsion force

q1 = Intensity of 1st point charge

q2 = Intensity of 2nd point charge

r = Distance among them

K = Coulomb’s constant


To calculate Coulomb's law, you can use our Coulomb's Law Calculator.


For a better understanding, we have a solved example of Coulomb’s law as follows:

What is the intensity of the force between two charges having a magnitude of 5 C which are 10 meters apart?

Given data

r = 10m
q1 = 5C
q2 = 5C

To Find

Intensity of the force = ?


To find the intensity of the force, we can use the formula listed below:

\[F = K(\frac{{{q_1}\;.\;{q_2}}}{{{{\rm{r}}^2}}})\]

Putting values in the formula:

F = 9.0 x 109 * 5 * 5 / (10 * 10)
F = 2.25 * 109 N