Essay by PaperNerd ContributorHigh School, 11th grade May 2001

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Robert Andrew Millikan was in born in Morrison, Illinois. He was educated at Columbia University and the universities of Berlin and Gottingen. He later joined the physics professor of the University of Chicago and in 1921 he became the director of California Institute of Technology¡¦s Norman Bridge Laboratory of Physics. Mallikan was well known in the physics world and has done experiments on x-rays, cosmic rays and Plank¡¦s constant (the constant you multiply by a light¡¦s frequency to get its quantum). In 1909, Mallikan used his famous ¡§oil drop¡¨ experiment and calculated the charge and mass of a single electron. He did so by measuring how quickly oil drops dropped between two charged metal plates. The positively charged plate was on the top and the negatively charged plate was placed on the bottom. By measuring and comparing how fast the oil drops fell when the plates were charged and uncharged, he calculated the charge of a single electron.

Because each measurement was a multiple of ¡V1.6 * 10-19 coulombs, he concluded this was the charge. After he found out the charge, he used the electron charge ¡V to ¡V mass ratio to find the mass of a single electron which was 9.109 *10-28 grams. These discoveries eventually brought Mallikan the Noble Prize for Physics in 1923.