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Ettingshausen Effect
The Ettingshausen effect (named for Albert von Ettingshausen) is a thermoelectric (or thermomagnetic) phenomenon that affects the electric current in a conductor when a magnetic field is present. Ettingshausen and his PhD student Walther Nernst were studying the Hall effect in bismuth, and noticed an unexpected perpendicular current flow when one side of the sample was heated. This is also known as the Nernst effect. Conversely, when applying a current (along the y-axis) and a perpendicular magnetic field (along the z-axis) a temperature gradient appears along the x-axis. Because of the Hall effect, electrons are forced to move perpendicular to the applied current. Due to the accumulation of electrons on one side of the sample, the number of collisions increases and a heating of the material occurs. This effect is quantified by the Ettingshausen coefficient ''P'', which is defined as: ::P=\frac where ''dT/dx'' is the temperature gradient that results from the ''y''-component ''Jy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albert Von Ettingshausen
Albert von Ettingshausen (30 March 1850 – 9 June 1932) was an Austrian physicist. He was professor of physics at Graz University of Technology, where he also taught electrical engineering. Earlier he was an assistant to Ludwig Boltzmann at the University of Graz. In 1886, he and his colleague Walther Nernst, then a PhD student at the University of Graz, jointly discovered the thermoelectric phenomena now known as the Ettingshausen effect and Nernst effect. Biography Albert Konstantin Karl Josef von Ettingshausen was born in Vienna as first of two children to Karl von Ettingshausen and Friederike Ettingshausen, née Kaltschmied. In 1854 the family moved to Graz. Albert’s sister Anna was born on February 11, 1856. Albert’s uncle was the mathematician and physicist Andreas von Ettingshausen, his cousin the botanist Constantin von Ettingshausen Albert von Ettingshausen studied physics and mathematics at the University of Graz. Still a student, he became an assistant profess ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermoelectric Effect
The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa via a thermocouple. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it, heat is transferred from one side to the other, creating a temperature difference. At the atomic scale, an applied temperature gradient causes charge carriers in the material to diffuse from the hot side to the cold side. This effect can be used to generate electricity, measure temperature or change the temperature of objects. Because the direction of heating and cooling is affected by the applied voltage, thermoelectric devices can be used as temperature controllers. The term "thermoelectric effect" encompasses three separately identified effects: the Seebeck effect, Peltier effect, and Thomson effect. The Seebeck and Peltier effects are different manifestations of the same physical process; textbooks may re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Current
An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving particles are called charge carriers, which may be one of several types of particles, depending on the conductor. In electric circuits the charge carriers are often electrons moving through a wire. In semiconductors they can be electrons or holes. In an electrolyte the charge carriers are ions, while in plasma, an ionized gas, they are ions and electrons. The SI unit of electric current is the ampere, or ''amp'', which is the flow of electric charge across a surface at the rate of one coulomb per second. The ampere (symbol: A) is an SI base unit. Electric current is measured using a device called an ammeter. Electric currents create magnetic fields, which are used in motors, generators, inductors, and transformers. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet's magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a nonuniform magnetic field exerts minuscule forces on "nonmagnetic" materials by three other magnetic effects: paramagnetism, diamagnetism, and antiferromagnetism, although these forces are usually so small they can only be detected by laboratory equipment. Magnetic fields surround magnetized materials, and are created by electric currents such as those used in electromagnets, and by electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function assigning a vector to each point of space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Walther Nernst
Walther Hermann Nernst (; 25 June 1864 – 18 November 1941) was a German chemist known for his work in thermodynamics, physical chemistry, electrochemistry, and solid state physics. His formulation of the Nernst heat theorem helped pave the way for the third law of thermodynamics, for which he won the 1920 Nobel Prize in Chemistry. He is also known for developing the Nernst equation in 1887. Life and career Early years Nernst was born in Briesen in West Prussia (now Wąbrzeźno, Poland) to Gustav Nernst (1827–1888) and Ottilie Nerger (1833–1876). His father was a country judge. Nernst had three older sisters and one younger brother. His third sister died of cholera. Nernst went to elementary school at Graudenz. He studied physics and mathematics at the universities of Zürich, Berlin, Graz and Würzburg, where he received his doctorate 1887. In 1889, he finished his habilitation at University of Leipzig. Personal attributes It was said that Nernst was mechanically min ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hall Effect
The Hall effect is the production of a voltage difference (the Hall voltage) across an electrical conductor that is transverse to an electric current in the conductor and to an applied magnetic field perpendicular to the current. It was discovered by Edwin Hall in 1879. A Hall effect can also occur across a void or hole in a semiconductor or metal plate, when current is injected via contacts that lie on the boundary or edge of the void or hole, and the charge flows outside the void or hole, in the metal or semiconductor. This Hall effect becomes observable in a perpendicular applied magnetic field across voltage contacts that lie on the boundary of the void on either side of a line connecting the current contacts. It exhibits apparent sign reversal in comparison to the standard "ordinary Hall effect" in the simply connected specimen, and depends only on the current injected from within the void. Superposition may also be realized in the Hall effect: first imagine the stand ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bismuth
Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs naturally, and its sulfide and oxide forms are important commercial ores. The free element is 86% as dense as lead. It is a brittle metal with a silvery-white color when freshly produced. Surface oxidation generally gives samples of the metal a somewhat rosy cast. Further oxidation under heat can give bismuth a vividly iridescent appearance due to thin-film interference. Bismuth is both the most diamagnetic element and one of the least thermally conductive metals known. Bismuth was long considered the element with the highest atomic mass whose nuclei do not spontaneously decay. However, in 2003 it was discovered to be extremely weakly radioactive. The metal's only primordial isotope, bismuth-209, experiences alpha decay at such a mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nernst Effect
In physics and chemistry, the Nernst effect (also termed first Nernst–Ettingshausen effect, after Walther Nernst and Albert von Ettingshausen) is a thermoelectric (or thermomagnetic) phenomenon observed when a sample allowing electrical conduction is subjected to a magnetic field and a temperature gradient normal (perpendicular) to each other. An electric field will be induced normal to both. This effect is quantified by the Nernst coefficient , ''N'', , which is defined to be ::, N, =\frac where E_Y is the y-component of the electric field that results from the magnetic field's z-component B_Z and the temperature gradient dT/dx. The reverse process is known as the Ettingshausen effect and also as the second Nernst–Ettingshausen effect. Physical picture Mobile energy carriers (for example conduction-band electrons in a semiconductor) will move along temperature gradients due to statistics and the relationship between temperature and kinetic energy. If there is a ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sketch Of Ettingshausen Effect
Sketch or Sketches may refer to: * Sketch (drawing), a rapidly executed freehand drawing that is not usually intended as a finished work Arts, entertainment and media * Sketch comedy, a series of short scenes or vignettes called sketches Film and television * ''Sketch'' (2007 film), a Malayalam film * ''Sketch'' (2018 film), a Tamil film * ''Sketch'' (TV series), a 2018 South Korean series * "Sketch", a 2008 episode of ''Skins'' ** Sketch (''Skins'' character) * Sketch with Kevin McDonald, a 2006 CBC television special Literature * Sketch story, or sketch, a very short piece of writing * ''Daily Sketch'', a British newspaper 1909–1971 * ''The Sketch'', a British illustrated weekly journal 1893–1959 Music * Sketch (music), an informal document prepared by a composer to assist in composition * The Sketches, a Pakistani Sufi folk rock band * ''Sketch'' (album), by Ex Norwegian, 2011 * ''Sketch'' (EP), by Hyomin, 2016 * ''Sketches'' (album), by Bert Jansch, 1990 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, and constantan used in strain gauges and thermocouples for temperature measurement. Copper is one of the few metals that can occur in nature in a directly usable metallic form ( native metals). This led to very early human use in several regions, from circa 8000 BC. Thousands of years later, it was the first metal to be smelted from sulfide ores, circa 5000 BC; the first metal to be cast into a shape in a mold, c. 4000 BC; and the first metal to be purposely alloyed with another metal, tin, to crea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver
Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earth's crust in the pure, free elemental form ("native silver"), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc refining. Silver has long been valued as a precious metal. Silver metal is used in many bullion coins, sometimes alongside gold: while it is more abundant than gold, it is much less abundant as a native metal. Its purity is typically measured on a per-mille basis; a 94%-pure alloy is described as "0.940 fine". As one of the seven metals of antiquity, silver has had an enduring role in most human cultures. Oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gold
Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile metal in a pure form. Chemically, gold is a transition metal and a group 11 element. It is one of the least reactive chemical elements and is solid under standard conditions. Gold often occurs in free elemental ( native state), as nuggets or grains, in rocks, veins, and alluvial deposits. It occurs in a solid solution series with the native element silver (as electrum), naturally alloyed with other metals like copper and palladium, and mineral inclusions such as within pyrite. Less commonly, it occurs in minerals as gold compounds, often with tellurium ( gold tellurides). Gold is resistant to most acids, though it does dissolve in aqua regia (a mixture of nitric acid and hydrochloric acid), forming a soluble tetrachloro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
