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Light Mill
The Crookes radiometer (also known as a light mill) consists of an airtight glass bulb containing a partial vacuum, with a set of vanes which are mounted on a spindle inside. The vanes rotate when exposed to light, with faster rotation for more intense light, providing a quantitative measurement of electromagnetic radiation intensity. The reason for the rotation was a cause of much scientific debate in the ten years following the invention of the device, but in 1879 the currently accepted explanation for the rotation was published. Today the device is mainly used in physics education as a demonstration of a heat engine run by light energy. It was invented in 1873 by the chemist Sir William Crookes as the by-product of some chemical research. In the course of very accurate quantitative chemical work, he was weighing samples in a partially evacuated chamber to reduce the effect of air currents, and noticed the weighings were disturbed when sunlight shone on the balance. Investigati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crookes Radiometer
The Crookes radiometer (also known as a light mill) consists of an airtight glass bulb containing a partial vacuum, with a set of vanes which are mounted on a spindle inside. The vanes rotate when exposed to light, with faster rotation for more intense light, providing a quantitative measurement of electromagnetic radiation intensity. The reason for the rotation was a cause of much scientific debate in the ten years following the invention of the device, but in 1879 the currently accepted explanation for the rotation was published. Today the device is mainly used in physics education as a demonstration of a heat engine run by light energy. It was invented in 1873 by the chemist Sir William Crookes as the by-product of some chemical research. In the course of very accurate quantitative chemical work, he was weighing samples in a partially evacuated chamber to reduce the effect of air currents, and noticed the weighings were disturbed when sunlight shone on the balance. Investigati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prefix
A prefix is an affix which is placed before the Word stem, stem of a word. Adding it to the beginning of one word changes it into another word. For example, when the prefix ''un-'' is added to the word ''happy'', it creates the word ''unhappy''. Particularly in the study of languages, a prefix is also called a preformative, because it alters the form of the words to which it is affixed. Prefixes, like other affixes, can be either inflectional, creating a new form of the word with the same basic meaning and same part of speech, lexical category (but playing a different role in the sentence), or Morphological derivation, derivational, creating a new word with a new semantics, semantic meaning and sometimes also a different Part of speech, lexical category. Prefixes, like all other affixes, are usually Bound and unbound morphemes, bound morphemes. In English language, English, there are no inflectional prefixes; English uses suffixes instead for that purpose. The word ''prefix'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyotr Nikolaevich Lebedev
Pyotr Nikolaevich Lebedev (; 24 February 1866 – 1 March 1912) was a Russian physicist. His name was also transliterated as Peter Lebedew and Peter Lebedev. Lebedev was a creator of first scientific school in Russia. Career Lebedev made his doctoral degree in Strasbourg under the supervision of August Kundt in 1887–1891. In 1891, he started working in Moscow State University in the group of Alexander Stoletov. There he made his famous experimental studies of electromagnetic waves. Along with Indian physicist Jagadish Chandra Bose he was one of the first to investigate millimeter waves, generating 50 GHz (6 mm) microwaves beginning in 1895 with a spark oscillator made of two platinum cylinders 1.5 cm long and 0.5 diameter immersed in kerosene at the focus of a parabolic reflector, and detecting the waves with an iron-constantan thermocouple detector.A. A. Kostenko, A. I. Nosich, P. F. Goldsmith, "Historical background and development of Soviet quasiopt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthur Schuster
Sir Franz Arthur Friedrich Schuster (12 September 1851 – 14 October 1934) was a German-born British physicist known for his work in spectroscopy, electrochemistry, optics, X-radiography and the application of harmonic analysis to physics. Schuster's integral is named after him. He contributed to making the University of Manchester a centre for the study of physics. Early years Arthur Schuster was born in Frankfurt am Main, Germany the son of Francis Joseph Schuster, a cotton merchant and banker, and his wife Marie Pfeiffer. Schuster's parents were married in 1849, converted from Judaism to Christianity, and brought up their children in that faith. In 1869, his father moved to Manchester where the family textile business was based. Arthur, who had been to school in Frankfurt and was studying in Geneva, joined his parents in 1870 and he and the other children became British citizens in 1875. Edgar Schuster (1897–1969) was his nephew. From his childhood, Schuster had been i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Clerk Maxwell
James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish mathematician and scientist responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism and light as different manifestations of the same phenomenon. Maxwell's equations for electromagnetism have been called the " second great unification in physics" where the first one had been realised by Isaac Newton. With the publication of "A Dynamical Theory of the Electromagnetic Field" in 1865, Maxwell demonstrated that electric and magnetic fields travel through space as waves moving at the speed of light. He proposed that light is an undulation in the same medium that is the cause of electric and magnetic phenomena. (This article accompanied an 8 December 1864 presentation by Maxwell to the Royal Society. His statement that "light and magnetism are affections of the same substance" is at page 499.) The unification of light and electrical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecule
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and biochemistry, the distinction from ions is dropped and ''molecule'' is often used when referring to polyatomic ions. A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O2); or it may be heteronuclear, a chemical compound composed of more than one element, e.g. water (two hydrogen atoms and one oxygen atom; H2O). In the kinetic theory of gases, the term ''molecule'' is often used for any gaseous particle regardless of its composition. This relaxes the requirement that a molecule contains two or more atoms, since the noble gases are individual atoms. Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic bonds, are typically not consid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black-body Absorption
A black body or blackbody is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. The name "black body" is given because it absorbs all colors of light. A black body also emits black-body radiation. In contrast, a white body is one with a "rough surface that reflects all incident rays completely and uniformly in all directions." A black body in thermal equilibrium (that is, at a constant temperature) emits electromagnetic black-body radiation. The radiation is emitted according to Planck's law, meaning that it has a spectrum that is determined by the temperature alone (see figure at right), not by the body's shape or composition. An ideal black body in thermal equilibrium has two main properties: #It is an ideal emitter: at every frequency, it emits as much or more thermal radiative energy as any other body at the same temperature. #It is a diffuse emitter: measured per unit area perpendicular to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on various reference points and thermometric substances for definition. The most common scales are the Celsius scale with the unit symbol °C (formerly called ''centigrade''), the Fahrenheit scale (°F), and the Kelvin scale (K), the latter being used predominantly for scientific purposes. The kelvin is one of the seven base units in the International System of Units (SI). Absolute zero, i.e., zero kelvin or −273.15 °C, is the lowest point in the thermodynamic temperature scale. Experimentally, it can be approached very closely but not actually reached, as recognized in the third law of thermodynamics. It would be impossible to extract energy as heat from a body at that temperature. Temperature is important in all fields of natur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiant Energy
Radiant may refer to: Computers, software, and video games * Radiant (software), a content management system * GtkRadiant, a level editor created by id Software for their games * Radiant AI, a technology developed by Bethesda Softworks for ''The Elder Scrolls'' games * Radiant, the team that opposes ''Dire'' on ''Dota 2'' Music * ''Radiant'' (Atlantic Starr album), 1981 * ''Radiant'' (Iris album), 2014 Ships * HMS ''Radiant'' (1916), a destroyer of the British Royal Navy launched in 1916 and sold in 1920 * USS ''Radiant'', the name of more than one United States Navy ship * ''Radiant'' (yacht), a 2009 Lürssen built yacht Others * Radiant heat, or thermal radiation, electromagnetic radiation emitted from the surface of an object which is due to the object's temperature * Radiant heating, a technology for heating indoor and outdoor areas * Radiant (Kitchen manufacturer), an Australian manufacturer of products for kitchens and laundries * Radiant (''Magic: The Gathering''), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science Museum
A science museum is a museum devoted primarily to science. Older science museums tended to concentrate on static displays of objects related to natural history, paleontology, geology, industry and industrial machinery, etc. Modern trends in museology Museology or museum studies is the study of museums. It explores the history of museums and their role in society, as well as the activities they engage in, including curating, preservation, public programming, and education. Terminology The w ... have broadened the range of subject matter and introduced many Interactivity, interactive exhibits. Modern science museums, increasingly referred to as 'science centres' or 'discovery centres', also feature technology. While the mission statements of science centres and modern museums may vary, they are commonly places that make science accessible and encourage the excitement of discovery. History As early as the Renaissance period, Aristocracy, aristocrats collected curiosities ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stroboscope
A stroboscope, also known as a strobe, is an instrument used to make a cyclically moving object appear to be slow-moving, or stationary. It consists of either a rotating disk with slots or holes or a lamp such as a flashtube which produces brief repetitive flashes of light. Usually, the rate of the stroboscope is adjustable to different frequencies. When a rotating or vibrating object is observed with the stroboscope at its vibration frequency (or a submultiple of it), it appears stationary. Thus stroboscopes are also used to measure frequency. The principle is used for the study of rotating, reciprocating, oscillating or vibrating objects. Machine parts and vibrating string are common examples. A stroboscope used to set the ignition timing of internal combustion engines is called a timing light. Mechanical In its simplest mechanical form, a stroboscope can be a rotating cylinder (or bowl with a raised edge) with evenly spaced holes or slots placed in the line of si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
