Robert Millikan
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40 free Robert Millikan trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Robert Millikan measured the charge of a single electron with a mist of oil droplets and a great deal of patience, and the result made him one of the most famous scientists in America. He went on to win a Nobel Prize, lead Caltech for more than two decades and become a public voice for science. This quiz collects the fun facts behind the textbook name: how the oil drop experiment worked and who else was in the lab, the theory he set out to demolish and ended up proving, the name he gave to a mysterious kind of radiation, his rivalries with other physicists, the careers of his sons, and the reasons institutions have recently reconsidered honoring him. It suits physics students revising the story of the electron, teachers looking for a classroom warm-up, and anyone who enjoys the human side of science. Every answer comes with a short explanation.
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Q 01Robert Millikan was studying which subject when his professor asked him to teach elementary physics?
Greek
Greek was Millikan's strong suit, and his professor insisted that anyone who did well in it could teach physics. Millikan spent a summer cramming from a textbook to stay ahead of the class.
Q 02Millikan spent a decade trying to disprove which physicist's 1905 particle theory of light?
Albert Einstein
Albert Einstein proposed that light arrives in packets, an idea Millikan was convinced had to be wrong. His own precise results matched the prediction in every detail, yet he doubted the interpretation for years.
Q 03Which name did Millikan coin for the mysterious radiation that grows stronger at high altitude?
Cosmic rays
Cosmic rays got their name from Millikan in the 1920s, after he confirmed the radiation was arriving from beyond Earth. Victor Hess had discovered it years earlier during daring balloon flights.
Q 04Which Caltech physicist cited Millikan's result as a warning about scientists fooling themselves?
Richard Feynman
Richard Feynman told Caltech's 1974 graduates that later experimenters nudged their results toward Millikan's slightly low electron charge. The accepted value crept upward only over many years.
Q 05Caltech took Millikan's name off its library in 2021 over his ties to which discredited movement?
Eugenics
Eugenics drew Millikan in as a trustee of the Human Betterment Foundation, which promoted compulsory sterilization. The Robert A. Millikan Library is now called Caltech Hall.
Q 06Millikan's droplet experiment first used which liquid, abandoned because it evaporated too fast?
Water
Water came first, but each droplet shrank as it evaporated while Millikan was timing it. Switching to oil, which barely evaporates, kept every drop's mass steady.
Q 07In World War I, Millikan's National Research Council work targeted which German weapon?
Submarines
Submarines were the target: as the council's vice chairman, Millikan played a major part in developing anti-submarine and meteorological devices.
Q 08Millikan's 1938 message to the far future was buried in a Westinghouse time capsule at which event?
New York World's Fair
New York World's Fair crowds arrived in 1939, and the capsule still lies fifty feet under Flushing Meadows, meant to stay sealed until the seventh millennium.
Q 09A large impact crater named for Robert Millikan lies in the northern hemisphere of which body?
Moon
Moon maps place Millikan crater on the far side, just north of a crater named for H. G. Wells, so it can never be seen from Earth.
Q 10In 1982 the United States honored Robert Millikan in its Great Americans series of which items?
Postage stamps
Postage stamps in the Great Americans series showed Millikan on a 37-cent issue released on January 26, 1982. The series ran from 1980 to 2000.
Q 11Which graduate student ran the oil drop experiment with Millikan yet was left off the paper as an author?
Harvey Fletcher
Harvey Fletcher let Millikan publish alone in exchange for sole authorship of a related result he could use as his dissertation. The deal stayed secret until after his death in 1981.
Q 12Millikan's oil drop assistant later became known as the father of which audio technology?
Stereophonic sound
Stereophonic sound was recorded by his Bell Labs team with conductor Leopold Stokowski in the early 1930s, among the earliest such recordings. He also built an early electronic hearing aid.
Q 13Millikan's electron charge came out slightly low because he misjudged which property of air?
Viscosity
Q 21At which university's Ryerson Physical Laboratory did Millikan carry out the oil drop experiment?
Chicago
Chicago hired Millikan as an assistant in 1896, and he stayed for a quarter of a century. A full professorship came only in 1910, after the oil drop work made his name.
Q 22Robert Millikan, who also enjoyed golf, was known as an enthusiastic player of which other sport?
Tennis
Tennis was Millikan's game: his Nobel biography calls him an enthusiastic player, with golf as another recreation.
Q 23Millikan served on the organizing committee for which major event held in Los Angeles in 1932?
The Olympic Games
The Olympic Games came to Los Angeles in 1932 with Millikan on the organizing committee, a sign of how prominent the Caltech leader had become in the city's civic life.
Viscosity sets the drag on a falling droplet, so the error carried straight into the result. Millikan's figure still landed within about 0.6 percent of the modern value.
Q 14Which law of drag on a small sphere did Millikan use to size each falling oil droplet?
Stokes' law
Stokes' law ties a tiny sphere's steady falling speed to its radius, so timing a drop with the field switched off revealed its weight. The law dates from 1851.
Q 15Which Austrian physicist feuded with Millikan after claiming charges smaller than the electron's?
Felix Ehrenhaft
Felix Ehrenhaft's claims were ultimately dismissed, but the unresolved dispute is widely believed to have cost Millikan the 1920 Nobel Prize. He won it three years later.
Q 16Whose measurement of the electron's charge-to-mass ratio let Millikan's result reveal its mass?
J. J. Thomson
J. J. Thomson had found only the ratio, so neither quantity was known on its own. Once Millikan pinned down the charge, the mass followed by simple division.
Q 17Millikan's light experiments on clean metal surfaces gave a precise measurement of whose constant?
Planck's
Planck's constant came out of his graphs of electron emission from various metals, measured between 1912 and 1915. Building the vacuum apparatus took years of work.
Q 18Which Nobel laureate argued against Millikan that radiation from space was charged particles?
Arthur Compton
Arthur Compton's worldwide survey found the rays stronger near the poles, steered by Earth's magnetic field as only charged particles could be. Millikan had insisted they were photons.
Q 19Which antimatter particle did Millikan's student Carl Anderson find in cloud chamber photographs?
Positron
Positron tracks confirmed Paul Dirac's prediction of a twin of the electron with the opposite charge. Anderson found them at Caltech while studying radiation from space under Millikan's supervision.
Q 20Which famous measurer of the speed of light invited Millikan to join his physics department in 1896?
Albert Michelson
Albert Michelson promised Millikan up to half his time for research, so he accepted even though another post paid twice the salary. Michelson later became the first American to win a science Nobel.
Q 24After a 1933 Long Beach disaster, Millikan led a committee on safer building against which hazard?
Earthquakes
Earthquakes became a public-safety cause after the Long Beach shock killed about 120 people. Millikan's committee of scientists, architects and builders urged stronger building codes in a report that June.
Q 25Millikan argued in lectures and several books that science could be reconciled with which pursuit?
Religion
Religion and science were allies for Millikan, a minister's son. When he told a 1930 scientific meeting that the Creator was still on the job, the remark made front-page news.
Q 26Millikan's oil drop experiment balanced gravity against which upward force between two metal plates?
Electric
Electric force from a voltage across the plates could be tuned until a charged drop hung motionless. From that balance and the drop's weight, Millikan worked out the charge it carried.
Q 27Millikan's Nobel Prize cited his work on the elementary charge and on which other effect?
Photoelectric
Photoelectric measurements, in which light knocks electrons out of a metal, shared the 1923 citation with his work on the electron's charge.
Q 28For his doctorate, Millikan studied light from molten gold and silver at which federal facility?
The U.S. Mint
The U.S. Mint gave Millikan the molten metal he needed to study how light from incandescent surfaces is polarized. The thesis earned him his doctorate in 1895.
Q 29Millikan's son Glenn married the daughter of which British mountaineer who died on Mount Everest?
George Mallory
George Mallory's daughter Clare married Glenn in 1938, and the family's bad luck with mountains continued: Glenn was killed by a falling rock while climbing in Tennessee in 1947.
Q 30Which East Coast university awarded Robert Millikan his doctorate in physics in 1895?
Columbia
Columbia made Millikan a Fellow in Physics in 1893, and his professors there then urged him to spend a year at the universities of Berlin and Göttingen.