Coulomb’s law quantifies the force between two point charges: proportional to the product of the charges and inversely proportional to the square of the distance, exactly like Newton’s gravitation. This section gives its statement, shows that all contact forces are a manifestation of it, retraces its experimental history, and extends it to multiple charges with the superposition principle.
- Coulomb’s law
- Contact forces are electromagnetic
- From the torsion balance to Franklin’s lightning
- Superposition principle
Try it — interactive simulation
A free positive charge moves in the field of a fixed negative charge: the trajectory depends on the sign and magnitude of the charges, just like a planet around the Sun but with Coulomb’s law instead of gravitation.