Robert Andrews Millikan (22 March 1868 – 19 December 1953) was an American physicist who is best known for his famous oil-drop experiment, which determined the charge of an electron.

Life and Career

He was born on 22 March 1868, in Morrison, Illinois, U.S. He received his undergraduate degree from Oberlin College in 1891, where he studied classics and mathematics. He then pursued graduate studies in physics at Columbia University and the University of Berlin, where he earned his Ph.D. in 1895 under the supervision of Max Planck.

After completing his doctorate, Millikan returned to the United States and worked briefly as an instructor at Oberlin College before moving to the University of Chicago, where he became a professor of physics in 1896. He spent the rest of his career at the University of Chicago, eventually serving as the head of the physics department.

In 1909, Millikan began his work on the measurement of the charge of an electron, which he accomplished using his oil-drop experiment. The experiment involved measuring the motion of charged oil droplets under the influence of an electric field. By measuring the droplets’ motion, Millikan was able to determine the charge of a single electron.


He also made significant contributions to the study of cosmic rays, and he was a vocal supporter of science education.

Throughout his career, Millikan remained committed to education, both as a teacher and as an advocate for science education.

He wrote several influential textbooks on physics, including “A First Course in Physics” and “Mechanics, Molecular Physics, and Heat.”


He died on 19 December 1953, in San Marino, California, U.S


He was awarded the Nobel Prize in Physics in 1923 for his contributions to the study of the photoelectric effect.

He received numerous honors and awards for his work, including the National Medal of Science, the Franklin Medal, and the Rumford Prize.

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