An application of Faraday’s constant is its use in calculating the Avogadro constant, as it relates the electric charge required to transfer moles of electrons in electrochemical reactions, thus linking macroscopic measurements to the microscopic world of atoms and molecules.
In 1909, Jean Perrin discovered the Avogadro constant and its relationship with the gram-molecule. In that same year, Robert Millikan, an American Physicist, conducted the now famous oil drop experiment and determined the charge for a single electron, q = 1.5924 x 10-19 C (about 0.6% off the currently accepted value). Dividing the Faraday constant, F, by q, we get the Avogadro constant:
Therefore, one Faraday (units of charge per mole) is the total charge for one gram-molecule (or mole) of electrons: