Robert Millikan and the oil drop experiment

Robert A. Millikan was an experimental scientist who studied the elementary electric charge and photoelectric effect.

He was born on the 22nd of March, 1868, in Morrison, Illinois and he died on the 19th of December, 1953, in San Marino, California.

He attended Maquoketa High School in Iowa, and later on in 1886 he entered the Oberlin College after working as a court reporter.

When in college, he actually took interest in Greek and Mathematics,but it wasn’t until he graduated college that he took interest in physics and in 1891 took a teaching post in elementary physics for two years.

He was appointed Fellow in Physics at Columbia University. He afterwards received his Ph.D. in 1895 for his research on the polarization of light emitted by incandescent surfaces using molten gold and silver.

He spent much time preparing textbooks and simplifying the teaching of physics. He was author or co-author of many books; A College Course in Physics, with S.W. Stratton (1898);Mechanics, Molecular Physics, and Heat (1902); The Theory of Optics, with C.R. Mann translated from the German (1903); A First Course in Physics, with H.G. Gale (1906); A Laboratory Course in Physics for Secondary Schools, with H.G. Gale (1907); Electricity, Sound, and Light, with J. Mills (1908); Practical Physics - revision of A First Course(1920); The Electron(1917; rev. eds. 1924, 1935).

As a scientist, Millikan made numerous momentous discoveries, chiefly in the fields of electricity, optics, and molecular physics and he made numerous contributions to scientific journals.

He verified experimentally Einstein's all-important photoelectric equation, and made the first direct photoelectric determination of Planck's constant h in 1912-1915.

During World War I, Millikan was Vice-Chairman of the National Research Council, and played a major part in developing anti-submarine and meteorological devices.

In 1921, he was appointed Director of the Norman Bridge Laboratory of Physics at the California Institute of Technology, Pasadena.

Millikan received numerous awards and prizes like the Comstock Prize of the National Academy of Sciences, the Edison Medal of the American Institute of Electrical Engineers, the Hughes Medal of the Royal Society of Great Britain, the Nobel Prize for Physics 1923.

His most famous success was the falling-drop method, also known as the Oil Drop.

In the Oil Drop Experiment Millikan put drops of oil in a chamber. A closed chamber with clear sides are placed with two parallel metal plates, which acquire a positive or negative charge when an electric current is applied. The Metal Plate placed in the middle of the chamber has holes that the oil can go through.

The space the oil is now “ionized” by Radiation. Like an X-ray. Then the air electrons attach themselves to the droplets of oil causing them to get a negative charge.

He added Light and looked at it through a microscope in order to see the oil more. It helps to measure the speed and the strength of electric field and density of oil drop.

Next, he added voltage to the chamber. The more voltage the chamber had, the slower the oil droplets would fall.

Robby knew that he could not physically tear apart the electrons from natural substances (water) offered convincing proof that electric charge exists in basic natural units. Millikan used this experiment to determine the size the charge of the electron.

Robby in this experiment was trying to learn if natural substances have electrons

Millikan is a very important person to us in this lesson, because right now we are learning how to find the electrons of natural substances like h2o or air, and we are learning now how they are used in the periodic table and how we can split the electrons from a substance. Robby was smart enough to use oil droplets instead of water-like droplets like most other scientists, which was one of the greatest improvements.

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