Millikan

Fri, 06 Nov 2009 05:33:34 +0100

Background?
Robert Andrew Millikan was born March 22, 1868 in Morrison, IL. He worked for a short period of time as a court reporter, and later entered into Oberlin College in Ohio. At first he was interested in Greek and Mathematics but his interests soon switched to Physics. He obtained his masters in physics around 1893. He authored many books including, A College Course in Physics, Mechanics, Molecular Physics, and Heat. He was a brilliant scientist and made many discoveries.

What did he discover?
Millikan determined the accurate charge of the electron in 1913. He used the "falling drop method" and proved that the quantity in his experiment was used for all electrons.

Equipment?
Millikan used a closed chamber with transparent sides which were fitted with two parallel metal plates which have either a positive or negative charge. An atomizer sprays a mist of oil drops into the chamber from the top. Because of gravity and air resistance the oil droplets fall through a small hole through the metal plate. The spaces between the holes were ionized by radiation, electrons attached themselves to the oil droplets as they were falling and cause them to accept a negative charge. A light source was set at right angles for Millikan to view this through a microscope. Because the mass could be determined by how fast one of the droplets fall, the amount of voltage needed to stop the droplet is used along with its mass to determine the overall electrical charge.

History?
During the time period of Millikan's experiment the second Balkan war ended along with Sung Chiao-jen assassination. In 1913 the 16th amendment was ratified into the constitution which gave the federal goverment the power to tax incomes.

millikan

Millikan