1785: Coulomb’s law - The book of science

Coulomb’s law
History
Analogies
Commentary

Charles-Augustin de Coulomb electromagnetism

Coulomb’s law

The force between two objects
that are electrostatically charged
is directly proportional
to the magnitude of the charges multiplied together
and inversely proportional
to the square of the distance between the objects.
This law applies
to any two charged objects with the same polarity,
to metal spheres
and to elementary particles.

History

Daniel Bernoulli and Alessandro Volta,
who measured the attractions of capacitor plates,
and Franz Ulrich Theodor Aepinus
all supposed the inverse-square law.
Joseph Priestley,
who experimented with charged spheres,
proposed the inverse-square law.
John Robison
also measured the force between two charged spheres,
and announced the inverse-square law.
Henry Cavendish,
who later weighed the world with his torsion balance,
discovered the relationship
to both distance and amount of charge
but did not publish.
Finally, Charles-Augustin de Coulomb,
after whom the law is named,
proved the inverse-square law with a torsion balance
and published the general law.

Analogies

Analogous to Isaac Newton’s law
of universal gravitation
is Coulomb’s law
of electrostatic attraction and repulsion,
which can be used to derive Gauss’s law
for electric fields,
which is analogous to Ampère’s circuital law
for magnetic fields,
which reminds me of the analogy
between atoms and solar systems.
Natural laws are only analogies
for conditions in the real world
but we are creatures of analogy;
all our experiences are analogies.

Coulomb’s law was a significant step in understanding electromagnetic forces. With the work of Volta, Ørsted, Ampère, and Faraday, it led to the invention of electric generators and motors.