Millikan oil-drop experiment
- First method for direct measurement of the electric charge of a single electron, originally performed in 1909 by Robert Millikan.He used a microscope to measure the rate of descent of tiny oil droplets directed through the top of a box. By halting the descent of droplets carrying their own electric charge by means of precisely adjusting the voltage between the box's metal top and bottom, he discovered that the electric charges on the drops were all whole-number multiples of a lowest value, the elementary electric charge itself, and thus that electric charge exists in basic natural units.
* * *▪ physicsfirst direct and compelling measurement of the electric charge of a single electron. It was performed originally in 1909 by the American physicist Robert A. Millikan (Millikan, Robert Andrews), who devised a straightforward method of measuring the minute electric charge that is present on many of the droplets in an oil mist. The force on any electric charge in an electric field is equal to the product of the charge and the electric field. Millikan was able to measure both the amount of electric force and magnitude of electric field on the tiny charge of an isolated oil droplet and from the data determine the magnitude of the charge itself.Millikan's original experiment or any modified version, such as the following, is called the oil-drop experiment. The apparatus associated with Millikan's oil-drop experiment is shown in the Figure. A closed chamber with transparent sides is fitted with two parallel metal plates, which acquire a positive or negative charge when an electric current is applied. At the start of the experiment, an atomizer sprays a fine mist of oil droplets into the upper portion of the chamber. Under the influence of gravity and air resistance, some of the oil droplets fall through a small hole cut in the top metal plate. When the space between the metal plates is ionized by radiation (e.g., X rays), electrons from the air attach themselves to the falling oil droplets, causing them to acquire a negative charge. A light source, set at right angles to a viewing microscope, illuminates the oil droplets and makes them appear as bright stars while they fall. The mass of a single charged droplet can be calculated by observing how fast it falls. By adjusting the potential difference, or voltage, between the metal plates, the speed of the droplet's motion can be increased or decreased; when the amount of upward electric force equals the known downward gravitational force, the charged droplet remains stationary. The amount of voltage needed to suspend a droplet is used along with its mass to determine the overall electric charge on the droplet. Through repeated application of this method, the values of the electric charge on individual oil drops are always whole-number multiples of a lowest value—that value being the elementary electric charge itself (about 1.602 10−19 coulomb). From the time of Millikan's original experiment, this method offered convincing proof that electric charge exists in basic natural units. All subsequent distinct methods of measuring the basic unit of electric charge point to its having the same fundamental value.
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Oil drop experiment — Millikan s setup for the oil drop experiment The oil drop experiment was an experiment performed by Robert Millikan and Harvey Fletcher in 1909 to measure the elementary electric charge (the charge of the electron). The experiment entailed… … Wikipedia
Oil-drop experiment — The purpose of Robert Millikan and Harvey Fletcher s oil drop experiment (1909) was to measure the electric charge of the electron. They did this by carefully balancing the gravitational and electric forces on tiny charged droplets of oil… … Wikipedia
Millikan’s oil drop experiment — Milikeno eksperimentas statusas T sritis fizika atitikmenys: angl. Millikan’s experiment; Millikan’s oil drop experiment vok. Millikanscher Öltröpfchenversuch, m; Millikanscher Versuch, m; Schwebetröpfchenversuch, m rus. опыт Милликена, m pranc.… … Fizikos terminų žodynas
Millikan’s oil drop experiment — Milikeno alyvos lašo eksperimentas statusas T sritis Standartizacija ir metrologija apibrėžtis Eksperimentas, kuriuo buvo išmatuotas elektrono krūvis. atitikmenys: angl. Millikan’s oil drop experiment vok. Millikanscher Öltröpfchenversuch, m;… … Penkiakalbis aiškinamasis metrologijos terminų žodynas
Millikan — is a surname, and may refer to People: Bud Millikan, Maryland Terrapins head basketball coach 1950 1967 Robert Andrews Millikan, Nobel prize winning physicist Glenn Allan Millikan, physiologist, inventor of Millikan oximeter and son of Robert… … Wikipedia
Millikan, Robert Andrews — ▪ American physicist born March 22, 1868, Morrison, Ill., U.S. died Dec. 19, 1953, San Marino, Calif. American physicist honoured with the Nobel Prize for Physics in 1923 for his study of the elementary electronic charge and the photoelectric… … Universalium
drop — droplike, adj. /drop/, n., v., dropped or dropt, dropping. n. 1. a small quantity of liquid that falls or is produced in a more or less spherical mass; a liquid globule. 2. the quantity of liquid contained in such a globule. 3. a very small… … Universalium
experiment — experimenter, experimentor, experimentator, n. n. /ik sper euh meuhnt/; v. /ek sper euh ment /, n. 1. a test, trial, or tentative procedure; an act or operation for the purpose of discovering something unknown or of testing a principle,… … Universalium
oil — oilless, adj. oillessness, n. oillike, adj. /oyl/, n. 1. any of a large class of substances typically unctuous, viscous, combustible, liquid at ordinary temperatures, and soluble in ether or alcohol but not in water: used for anointing, perfuming … Universalium
Millikan, Robert (Andrews) — born March 22, 1868, Morrison, Ill., U.S. died Dec. 19, 1953, San Marino, Calif. U.S. physicist. He received his doctorate from Columbia University and taught physics at the University of Chicago (1896–1921) and the California Institute of… … Universalium