Millikan's oil drop experiment attempts to measure the charge on a single electron, e, by measuring the charge on tiny oil drops suspended in an electrostatic field. It is assumed that the charge on the oil drops is due to just a small number of excess electrons. The charges 3.90×10−19 C, 6.50×10−19 C, and 9.10×10−19 C are measured on three drops of oil. The charge of an electron is deduced to be,
(a) 1.3×10−19 C.
(b) 1.6×10−19 C.
(c) 2.6×10−19 C.
(d) 3.9×10−19 C.