R.A. Millikan (1868 1953) devised a method known as oil drop experiment (1906-14), to determine the charge on the electrons. 1-le found that the charge on the electron to be- 1.6 x 10-19 C. The present accepted value of electrical charge is – 1.6022 x 10-19 C.
The mass of the electron (me) was determined by combining these results with Thomson’s value of e/me ratio.
me = e / (e/me)
= 9.1094 x 10-31 kg