text: In natural units, this quantity equals 0.303, or the square root of four pi times the fine structureconstant.
full_question: In natural units, this quantity equals 0.303, or the square root of four pi times the fine structureconstant. The product of this quantity, the Josephson constant, and the von Klitzing constant equals two.It is raised to the fourth power in the Rydberg formula. An experimental measurement of this quantity,which differed from the true value by five standard deviations, was described as "Cargo Cult Science" byRichard Feynman. For quarks, this constant is prefixed by either (*) two-thirds or negative-one-third. Thisconstant was determined by manipulating voltage until the terminal velocity of falling oil droplets was reached. For10 points, name this constant measured by Millikan, whose magnitude is around 1.6 times ten to the negativenineteen, and which is symbolized e.
first_sentence: In natural units, this quantity equals 0.303, or the square root of four pi times the fine structureconstant.
raw_answer:  elementary charge [or e until it is read; or fundamental charge; or charge on a proton; or charge on an electron] 