The unit of measurement for charge is Coulomb. Now, every particle of electron contains a charge equal to 1.602×10⁻¹⁹ C. So if there are 3 electrons in the oil droplet, then the total charge would be:
Total charge = 3 electrons(1.602×10⁻¹⁹ C/ electron)
Total charge = 4.806×10⁻¹⁹ C
