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Encyclopedia > Mercury vapor lamp

A Mercury-vapor lamp is a gas discharge lamp which uses mercury in an excited state to produce light. The arc discharge is generally confined to a small fused quartz tube mounted within a larger borosilicate glass bulb. The outer bulb may be clear or coated with a phosphor; in either case, the outer bulb provides thermal insulation, protection from ultraviolet radiation, and a convenient mounting for the fused quartz arc tube.-1... For the Linux, Apache, MySQL, [Perl, PHP, or Python] (a popular web server combination), see the article at LAMP. A lamp in general is any device that produces light. ... General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery white Atomic mass 200. ... Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye or, in a technical or scientific setting, electromagnetic radiation of any wavelength. ... Fused quartz is a man-made material manufactured principally from sands. ... Borosilicate glass is a particular type of glass, better known under the brand names Pyrex and Kimax. ... A phosphor is a substance that can exhibit the phenomenon of fluorescence (glowing during absorption of radiation of another kind) or phosphorescence (sustained glowing without further stimulus). ... This page refers to thermal insulation. ... Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. ...


Mercury vapor lamps (and their relatives) are often used because they are relatively efficient while still offering better color rendition than either low- or even high-pressure sodium vapor lamps. They also offer a very long lifetime. Efficiency is the capability of acting or producing effectively with a minimum of waste, expense, or unnecessary effort. ... A sodium vapor lamp is a gas discharge lamp which uses sodium in an excited state to produce light. ...


The mercury vapor lamp is a negative resistance device and requires auxiliary electronics to prevent it from destroying itself. The auxiliary electronics are substantially similar to the ballasts used with fluorescent lamps. In electrical circuits, static resistance is the ratio of the voltage across a circuit element to the current through it. ... An electrical network or electrical circuit is an interconnection of analog electrical elements such as resistors, inductors, capacitors, diodes, switches and transistors. ... A compact fluorescent lamp with an integrated electronic ballast A fluorescent lamp is a type of lamp that uses electricity to excite mercury vapor in argon or neon gas, producing short-wave ultraviolet light. ...


Also like fluorescent lamps, mercury vapor lamps usually require a starting aid. In this case, though, the starting aid is usually contained within the mercury vapor lamp itself. A third electrode is mounted near one of the main electrodes and connected through a resistor to the other main electrode. When power is applied, there is sufficient voltage to strike an arc between the starting electrode and the adjacent main electrode. This arc discharge eventually provides enough ionized mercury to strike an arc between the main electrodes. Occasionally, a thermal switch will also be installed to short the starting electrode to the adjacent main electrode, completely suppressing the starting arc once the main arc strikes. An electrode is a conductor used to make contact with a nonmetallic part of a circuit (e. ... Resistor symbols A resistor is a two-terminal electrical component that creates an electrical potential difference across its terminals that is proportional to the current passing through it. ... In the physical sciences, potential difference is the difference in potential between two points in a conservative vector field. ... An ion is an elementary particle or system of elementary particles with a net electric charge. ...


When the lamp is first turned on, it will produce a dark blue glow because only a small amount of the mercury is ionized and the gas pressure in the arc tube is very low (so much of the light is produced in the ultraviolet mercury bands). As the main arc strikes and the gas heats up and increases in pressure, the light shifts into the visible range and the high gas pressure causes the mercury emission bands to broaden somewhat, producing a light that appears more-white to the human eye (although it is still not a continuous spectrum). Even at full intensity, the light from a mercury vapor lamp with no phosphors is distinctly bluish in color. For other uses, see Blue (disambiguation) Blue is one of the three primary additive colours; blue light has the shortest wavelength range (about 420-490 nanometres) of the three primary colours. ... Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. ... The optical spectrum (light or visible spectrum) is the portion of the electromagnetic spectrum that is visible to the human eye. ... White is a color (more accurately it contains all the colors of the visible spectrum and is sometimes described as an achromatic color—black is the absence of color) that has high brightness but zero hue. ... In mathematics and physics, continuous spectrum is, roughly speaking, a non-countable set of eigenvalues of an operator. ...


To correct this, many mercury vapor lamps coat the inside of the outer bulb with a phosphor that converts some portion of the ultraviolet emissions into red light. This helps to fill in the otherwise very-deficient red end of the electromagnetic spectrum. These lamps are quite-sensibly known as "color corrected" lamps. A phosphor is a substance that can exhibit the phenomenon of fluorescence (glowing during absorption of radiation of another kind) or phosphorescence (sustained glowing without further stimulus). ... The electromagnetic spectrum encompasses all possible wavelengths of electromagnetic radiation. ...


A closely-related lamp design called the Metal halide lamp uses various other elements in an amalgam with the mercury. Sodium iodide and Scandium iodide are commonly in use. These lamps can produce much better quality light without resorting to phosphors. If they use a starting electrode (as described above), there is always a thermal shorting switch to eliminate any electrical potential between the main electrode and the starting electrode once the lamp is lit. (This electrical potential in the presence of the halides can cause the failure of the glass/metal seal). More modern metal halide system do not use a separate starting electrode; instead, the lamp is started using high voltage pulses as with high-pressure sodium vapor lamps. "MetalArc" is Osram Sylvania's trademark for their metal halide lamps; "Arcstream" and "MultiVapor" are General Electric's trademark. Besides their use in traditional outdoor lighting, these lamps now appear in most computer and video projectors. Metal halide lamps are similar to mercury vapor lamps, but instead of just mercury, they also contain all metals in the halide group of the periodic table (Hence the name). ... An amalgam is an alloy of mercury. ... General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Atomic mass 22. ... General Name, Symbol, Number iodine, I, 53 Chemical series halogens Group, Period, Block 17, 5, p Appearance violet-dark gray, lustrous Atomic mass 126. ... General Name, Symbol, Number scandium, Sc, 21 Chemical series transition metals Group, Period, Block 3, 4, d Appearance silvery white Atomic mass 44. ... General Name, Symbol, Number iodine, I, 53 Chemical series halogens Group, Period, Block 17, 5, p Appearance violet-dark gray, lustrous Atomic mass 126. ... In the physical sciences, potential difference is the difference in potential between two points in a conservative vector field. ... OSRAM is one of the two largest lighting manufacturers in the world. ... Sylvania literally means forest land. Ít is used to mean several different things: Sylvania is the name of several places in the United States of America: Sylvania, Alabama Sylvania, Georgia Sylvania, Ohio Sylvania is also the name of a company manufacturing electrical devices; once a subsidiary of General Telephone and... The General Electric Company, or GE, (NYSE: GE) is a multinational technology and services company. ... A video projector takes a video signal and projects the corresponding image on a screen. ...


Light pollution considerations

For placements where light pollution is of prime importance (for example, an observatory parking lot), low pressure sodium is preferred. As it emits light on only one wavelength, it is the easiest to filter out. Mercury vapor lamps without any phosphor are second best; they produce only a few distinct mercury lines that need to be filtered out. Light pollution (also known as photopollution, luminous pollution) is excess or obtrusive light created by humans. ... Categories: Stub | Astronomical observatories ... Parking lot is the American English term that refers to a cleared area that is more or less level and is intended for parking vehicles. ...


Ultraviolet hazards

All mercury vapor lamps (including metal halide lamps) must contain a feature (or be installed in a fixture that contains a feature) that prevents ultraviolet radiation from escaping. Usually, the borosilicate glass outer bulb of the lamp performs this function but special care must be taken if the lamp is installed in a situation where this outer envelope can become damaged. There have been documented cases of lamps being damaged in gymnasiums and sun burns and eye inflammation have resulted. When used in locations like gyms, the fixture should contain a strong outer guard or an outer lens to protect the lamp's outer bulb. Also, special "safety" lamps are made which will burn out if the outer glass is broken. This is usually achieved by a thin carbon srip used to connect one of the electrodes, which will burn up in the presence of air. Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. ... Gymnasium can have following meanings: Gymnasium (ancient Greece)—an educational and sporting institution in Ancient Greece Gymnasium—a school of secondary education found in several European countries (approx. ... A sunburn is a radiation burn to the skin produced by overexposure to ultraviolet (UV) light, commonly from the suns rays. ... Combustion or burning is an exothermic reaction between a substance (the fuel) and a gas (the oxidizer), usually O2, to release heat. ...


See also

  • Hydrargyrum Medium-Arc Iodide
Sources of light / lighting (edit me...)
Natural/prehistoric light sources:
Bioluminescence (Fireflies, Foxfire, et cetera) | Celestial objects | Lightning
Combustion-based light sources:
Acetylene/Carbide lamps | Candle | Davy lamps | Fire | Gas lighting | Kerosene lamp | Limelight | Oil lamp | Rushlight
Nuclear/direct chemical light sources:
Betalights | Chemoluminescence/Lightsticks
Electric light sources:
Arc lamp | Incandescent | Fluorescent
High-intensity discharge:
HMI lamps | Mercury-vapor lamps | Metal halide lamps | Sodium vapor lamps | Xenon arc lamps
Other electric:
Electroluminescent (EL) lamps | Inductive lighting | LEDs | Neon and argon lamps | Sulfur lamp | Xenon flash lamps | Yablochkov candle

 
 

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