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Cold-cathode Fluorescent Lamp
A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet light that then causes a phosphor coating on the inside of the lamp to glow. A fluorescent lamp converts electrical energy into useful light much more efficiently than an incandescent lamp. The typical luminous efficacy of fluorescent lighting systems is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output. For comparison, the luminous efficacy of an incandescent bulb may only be 16 lumens per watt. Fluorescent lamp fixtures are more costly than incandescent lamps because, among other things, they require a ballast to regulate current through the lamp, but the initial cost is offset by a much lower running cost. Compact fluorescent lamps are now available in the same popular sizes as incandesc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescent Lamps Artistic
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, than the absorbed radiation. A perceptible example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the electromagnetic spectrum (invisible to the human eye), while the emitted light is in the visible region; this gives the fluorescent substance a distinct color that can only be seen when the substance has been exposed to UV light. Fluorescent materials cease to glow nearly immediately when the radiation source stops, unlike phosphorescent materials, which continue to emit light for some time after. Fluorescence has many practical applications, including mineralogy, gemology, medicine, chemical sensors (fluorescence spectroscopy), fluorescent labelling, dyes, biological detectors, cosmic-ray detection, vacu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Energy-saving
Energy conservation is the effort to reduce wasteful energy consumption by using fewer energy services. This can be done by using energy more effectively (using less energy for continuous service) or changing one's behavior to use less service (for example, by driving less). Energy conservation can be achieved through energy efficiency, which has a number of advantages, including a reduction in greenhouse gas emissions, a smaller carbon footprint, and cost, water, and energy savings. Energy conservation is an essential factor in building design and construction. It has increased in importance since the 1970s, as 40% of energy use in the U.S. is in buildings. Recently, concern over the effects of climate change and global warming has emphasized the importance of energy conservation. Energy can only be transformed from one form to another, such as when heat energy is converted into vehicle motive power or when water flow's kinetic energy is converted into electricity in hydroelectr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geissler Tube
A Geissler tube is an early gas discharge tube used to demonstrate the principles of electrical glow discharge, similar to modern neon lighting. The tube was invented by the German physicist and glassblower Heinrich Geissler in 1857. It consists of a sealed, partially evacuated glass cylinder of various shapes with a metal electrode at each end, containing rarefied gasses such as neon, argon, or air; mercury vapor or other conductive fluids; or ionizable minerals or metals, such as sodium. When a high voltage is applied between the electrodes, an electrical current flows through the tube. The current dissociates electrons from the gas molecules, creating ions, and when the electrons recombine with the ions, the gas emits light by fluorescence. The color of light emitted is characteristic of the material within the tube, and many different colors and lighting effects can be achieved. The first gas-discharge lamps, Geissler tubes were novelty items, made in many artistic shapes a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercury Vacuum Pump
The Sprengel pump is a vacuum pump that uses drops of mercury falling through a small-bore capillary tube to trap air from the system to be evacuated. It was invented by Hanover-born chemist Hermann Sprengel in 1865 while he was working in London. The pump created the highest vacuum achievable at that time, less than 1 mPa (approximately 1×10−8 atm). Operation The supply of mercury is contained in the reservoir on the left. It flows over into the bulb ''B'', where it forms drops which fall into the long tube on the right. These drops entrap between them the air in ''B''. The mercury which runs out is collected and poured back into reservoir on the left. In this manner practically all the air can be removed from the bulb ''B'', and hence from any vessel ''R'', which may be connected with ''B''. At ''M'' is a manometer which indicates the pressure in the vessel ''R'', which is being exhausted. Falling mercury drops compress the air to atmospheric pressure which is released wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heinrich Geissler
Heinrich may refer to: People * Heinrich (given name), a given name (including a list of people with the name) * Heinrich (surname), a surname (including a list of people with the name) *Hetty (given name), a given name (including a list of people with the name) Places * Heinrich (crater), a lunar crater * Heinrich-Hertz-Turm, a telecommunication tower and landmark of Hamburg, Germany Other uses * Heinrich event, a climatic event during the last ice age * Heinrich (card game), a north German card game * Heinrich (farmer), participant in the German TV show a ''Farmer Wants a Wife'' * Heinrich Greif Prize, an award of the former East German government * Heinrich Heine Prize, the name of two different awards * Heinrich Mann Prize, a literary award given by the Berlin Academy of Art * Heinrich Tessenow Medal, an architecture prize established in 1963 * Heinrich Wieland Prize, an annual award in the fields of chemistry, biochemistry and physiology * Heinrich, known as Haida in Ja ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Random House
Random House is an American book publisher and the largest general-interest paperback publisher in the world. The company has several independently managed subsidiaries around the world. It is part of Penguin Random House, which is owned by German media conglomerate Bertelsmann. History Random House was founded in 1927 by Bennett Cerf and Donald Klopfer, two years after they acquired the Modern Library imprint from publisher Horace Liveright, which reprints classic works of literature. Cerf is quoted as saying, "We just said we were going to publish a few books on the side at random," which suggested the name Random House. In 1934 they published the first authorized edition of James Joyce's novel ''Ulysses'' in the Anglophone world. ''Ulysses'' transformed Random House into a formidable publisher over the next two decades. In 1936, it absorbed the firm of Smith and Haas—Robert Haas became the third partner until retiring and selling his share back to Cerf and Klopfer in 19 ... [...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] |
Michael Faraday
Michael Faraday (; 22 September 1791 – 25 August 1867) was an English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic induction, diamagnetism and electrolysis. Although Faraday received little formal education, he was one of the most influential scientists in history. It was by his research on the magnetic field around a conductor carrying a direct current that Faraday established the concept of the electromagnetic field in physics. Faraday also established that magnetism could affect rays of light and that there was an underlying relationship between the two phenomena.. the 1911 Encyclopædia Britannica. He similarly discovered the principles of electromagnetic induction, diamagnetism, and the laws of electrolysis. His inventions of electromagnetic rotary devices formed the foundation of electric motor technology, and it was largely due to his efforts t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorite
Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 4 as fluorite. Pure fluorite is colourless and transparent, both in visible and ultraviolet light, but impurities usually make it a colorful mineral and the stone has ornamental and lapidary uses. Industrially, fluorite is used as a flux for smelting, and in the production of certain glasses and enamels. The purest grades of fluorite are a source of fluoride for hydrofluoric acid manufacture, which is the intermediate source of most fluorine-containing fine chemicals. Optically clear transparent fluorite lenses have low dispersion, so lenses made from it exhibit less chromatic aberration, making them valuable in microscopes and telescopes. Fluorite optics are also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Cambridge
, mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Scholars of the University of Cambridge , type = Public research university , endowment = £7.121 billion (including colleges) , budget = £2.308 billion (excluding colleges) , chancellor = The Lord Sainsbury of Turville , vice_chancellor = Anthony Freeling , students = 24,450 (2020) , undergrad = 12,850 (2020) , postgrad = 11,600 (2020) , city = Cambridge , country = England , campus_type = , sporting_affiliations = The Sporting Blue , colours = Cambridge Blue , website = , logo = University of Cambridge logo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sir George Stokes, 1st Baronet
Sir George Gabriel Stokes, 1st Baronet, (; 13 August 1819 – 1 February 1903) was an Irish English physicist and mathematician. Born in County Sligo, Ireland, Stokes spent all of his career at the University of Cambridge, where he was the Lucasian Professor of Mathematics from 1849 until his death in 1903. As a physicist, Stokes made seminal contributions to fluid mechanics, including the Navier–Stokes equations; and to physical optics, with notable works on polarization and fluorescence. As a mathematician, he popularised "Stokes' theorem" in vector calculus and contributed to the theory of asymptotic expansions. Stokes, along with Felix Hoppe-Seyler, first demonstrated the oxygen transport function of hemoglobin and showed color changes produced by aeration of hemoglobin solutions. Stokes was made a baronet by the British monarch in 1889. In 1893 he received the Royal Society's Copley Medal, then the most prestigious scientific prize in the world, "for his researches and ... [...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 ordinary con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
