Robert+Millikan

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Millikan was an American experimental physicist. He recieved his doctorate of physics in 1895 from Columbia university. He was the first to ever receive a PHD in that department. While a professor at the University of Chicago, Millikan and Harvey Fletcher began work on an oil droplet experiment (above). The experiment entailed balancing downward gravitational forces with the buoyant and electric forces on tiny charged droplets of oil suspended in the air between two electrodes. Using a known electric field, Millikan and Fletcher could determine the charge on oil droplets in mechanical equilibrium. By repeating the experiment for many oil droplets, they confirmed that the charges were all multiples of some fundamental value, and calculated it to be 1.5924(17)×10−19 C, within one percent of the currently accepted value of 1.602176487(40)×10−19 C. They proposed that this was the charge of a single electron. After his discovery of the electron charge, many physics students have repeated his experiment