Benjamin Franklin identified lightning with electricity when he discovered that lightning conducted, or flowed, through a metal key could be used to charge a jar, thus proving that lightning was an electric discharge and current. Franklin explained that static electricity as a single fluid that could appear both positive and negative. When a substance contained a greater than normal quantity of electric fluid, it possessed one kind of electric charge; when it contained a less than normal quantity, it possessed the other kind.
Franklin was also the first person to estimate the size of atom. Franklin observed that a teaspoon full of oil would cover the surface of an entire body of water covering half an acre at a pond at Clapham. Franklin measured the ripples off the water surface.
Robert Millikan also had an oil drop experiment, though his experiment entailed balancing the downward gravitational force with the upward drag and the electric forces on tiny charged droplets of oil between the two metal electrodes. Millikan knew the density of the oil, their masses, therefore the gravitational and buoyant forces as well. He calculated the electric field so he could measure the droplet’s charge.
The charge he calculated on a single electron was 1.592×10−19 C, though at this time, the existence of subatomic particles was not universally accepted just yet. Millikan won the Nobel Prize in Physics because of this experiment.
Charles-Augustin de Coulomb invented a device, dubbed the torsion balance, that allowed him to measure very small charges and experimentally estimate the force of attraction or repulsion between two charged bodies. The data he obtained through his extensive use of the torsion balance enabled Coulomb to formulate one of the fundamental laws of electromagnetism, which bears his name, Coulomb's law.
Coulomb’s law describes the electrostatic interaction between electrically charged particles. Coulomb’s law states that the magnitude of the force between two point charges is directly proportional to the charges of two objects and inversely proportional to the square of the distance between them, the force is along a straight line joining them. If the charges have the same sign same, they will repel, and if they have the opposite signs, they...