<P> The electron 's charge was more carefully measured by the American physicists Robert Millikan and Harvey Fletcher in their oil - drop experiment of 1909 , the results of which were published in 1911 . This experiment used an electric field to prevent a charged droplet of oil from falling as a result of gravity . This device could measure the electric charge from as few as 1 -- 150 ions with an error margin of less than 0.3 % . Comparable experiments had been done earlier by Thomson 's team , using clouds of charged water droplets generated by electrolysis , and in 1911 by Abram Ioffe , who independently obtained the same result as Millikan using charged microparticles of metals , then published his results in 1913 . However , oil drops were more stable than water drops because of their slower evaporation rate , and thus more suited to precise experimentation over longer periods of time . </P>
how was the charge of an electron discovered
The electron 's charge was more carefully measured by the American physicists Robert Millikan and Harvey Fletcher in their oil - drop experiment of 1909 , the results of which were published in 1911 . This experiment used an electric field to prevent a charged droplet of oil from falling as a result of gravity . This device could measure the electric charge from as few as 1 -- 150 ions with an error margin of less than 0.3 % .