1909 – USA
‘The charge on the electron’
Millikan measured the charge on the electron.
His experiment showed that the electron is the fundamental unit of electricity; that is, electricity is the flow of electrons. From the experiment Millikan calculated the basic charge on an electron to be 1.6 × 10-19 coulomb. This charge cannot be subdivided – by convention this charge is called unit negative, -1, charge.
Millikan also determined that the electron has only about 1/1837 the mass of a proton, or 9.1 × 10-31 kilogram.