Historical note
Charles-Augustin de Coulomb (1736–1806) was a French military engineer who had developed a torsion balance of extraordinary sensitivity. In 1785 he used it to measure the force between electric charges, showing that it follows an inverse square of the distance: the same structure as Newton’s gravity, but with charges in place of masses (Simonyi 2012, ch. 4).
Thirty years earlier, in 1752, Benjamin Franklin (1706–1790) had carried out his famous — and highly dangerous — kite experiment in a storm, showing that lightning is an electrical phenomenon. A Russian imitator, Georg Wilhelm Richmann, was killed attempting to repeat the experiment in 1753 (Brandt 2009, ch. 12).
Michael Faraday (1791–1867), the son of a blacksmith and almost entirely self-taught, introduced the concept of the electric field, the “lines of force”, which transformed the very way of thinking about interactions at a distance (Guillen 1995, ch. 3).
The thread linking these three figures is the shift from a physics of forces at a distance to a physics of fields. Coulomb measures the force between charges as an instantaneous fact between two points; Faraday, half a century later, imagines space itself filled with lines of force that transmit the interaction — an idea that would open the way to all of electromagnetism.
For full references to the works cited, see Riferimenti bibliografici.
Links
Topics: Electrostatics Concepts: Coulomb’s law · Electric field
Related exercises: Drill — distance for a given field · Field of a point charge at 9 cm · Ranking the field for various configurations