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International Candle
Candlepower (abbreviated as cp or CP) is a unit of measurement for luminous intensity. It expresses levels of light intensity relative to the light emitted by a candle of specific size and constituents. The historical candlepower is equal to 0.981 candelas. In modern usage, ''candlepower'' is sometimes used as a synonym for ''candela''. History The term candlepower was originally defined in the United Kingdom, by the Metropolitan Gas Act 1860, as the light produced by a pure spermaceti candle that weighs and burns at a rate of . Spermaceti is a material from the heads of sperm whales, and was once used to make high-quality candles. At the time the UK established candlepower as a unit, the French standard of light was based on the illumination from a Carcel burner, which defined the illumination that emanates from a lamp burning pure colza oil (obtained from the seed of the plant '' Brassica campestris'') at a defined rate. Ten standard candles equaled about one Carcel burner. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luminous Intensity
In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye. The SI unit of luminous intensity is the candela (cd), an SI base unit. Measurement Photometry deals with the measurement of visible light as perceived by human eyes. The human eye can only see light in the visible spectrum and has different sensitivities to light of different wavelengths within the spectrum. When adapted for bright conditions ( photopic vision), the eye is most sensitive to yellow-green light at 555 nm. Light with the same radiant intensity at other wavelengths has a lower luminous intensity. The curve which represents the response of the human eye to light is a defined standard function or established by the International Commission on Illumination (CIE, for ''Commission Internationale de l'Écla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hefner Lamp
The Hefner lamp, or in German ''Hefnerkerze'', is a flame lamp used in photometry that burns amyl acetate. The lamp was invented by Friedrich von Hefner-Alteneck in 1884 and he proposed its use as a standard flame for photometric purposes with a luminous intensity unit of the Hefnerkerze (HK). The lamp was specified as having a 40 mm flame height and an 8 mm diameter wick. The Hefner lamp provided the German, Austrian, and Scandinavian standard for luminosity during the late nineteenth and early twentieth centuries. The unit of light intensity was defined as that produced by the lamp burning amyl acetate with a 40 mm flame height. The light unit was adopted by the German gas industry in 1890 and known as the ''Hefnereinheit''. In 1897 it was also adopted by the Association of German Electrical Engineers under the name ''Hefnerkerze'' (HK). Germany moved to using the new candle (NC) from 1 July 1942 and the candela (cd) from 1948. :1 Hefnerkerze is about 0.920 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Units Of Luminous Intensity
Unit may refer to: General measurement * Unit of measurement, a definite magnitude of a physical quantity, defined and adopted by convention or by law **International System of Units (SI), modern form of the metric system **English units, historical units of measurement used in England up to 1824 **Unit of length Science and technology Physical sciences * Natural unit, a physical unit of measurement * Geological unit or rock unit, a volume of identifiable rock or ice * Astronomical unit, a unit of length roughly between the Earth and the Sun Chemistry and medicine * Equivalent (chemistry), a unit of measurement used in chemistry and biology * Unit, a vessel or section of a chemical plant * Blood unit, a measurement in blood transfusion * Enzyme unit, a measurement of active enzyme in a sample * International unit, a unit of measurement for nutrients and drugs Mathematics * Unit number, the number 1 * Unit, identity element * Unit (ring theory), an element that is inverti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Candles
A candle is an ignitable candle wick, wick embedded in wax, or another flammable solid substance such as tallow, that provides light, and in some cases, a Aroma compound, fragrance. A candle can also provide heat or a method of keeping time. Candles have been used for over two millennia around the world, and were a significant form of indoor lighting until the invention of other types of light sources. Although electric light has largely made candle use nonessential for illumination, candles are still commonly used for functional, symbolic and aesthetic purposes and in specific cultural and religious settings. Early candles may be made of beeswax, but these candles were expensive and their use was limited to the elite and the churches. Tallow was a cheaper but a less aesthetically pleasing alternative. A variety of different materials have been developed in the modern era for making candles, including paraffin wax, which together with efficient production techniques, made can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lumen (unit)
The lumen (symbol: lm) is the SI unit of luminous flux, which quantifies the perceived power of visible light emitted by a source. Luminous flux differs from power (radiant flux), which encompasses all electromagnetic waves emitted, including non-visible ones such as thermal radiation (infrared). By contrast, luminous flux is weighted according to a model (a " luminosity function") of the human eye's sensitivity to various wavelengths; this weighting is standardized by the CIE and ISO. The lumen is defined as equivalent to one candela-steradian (symbol cd·sr): : 1 lm = 1 cd·sr. A full sphere has a solid angle of 4π steradians (≈ 12.56637 sr), so an isotropic light source (that uniformly radiates in all directions) with a luminous intensity of one candela has a total luminous flux of :. One lux is one lumen per square metre. Explanation If a light source emits one candela of luminous intensity uniformly across a solid angle of one steradian, the total luminous flux e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Obsolete Units Of Measurement
This is a list of obsolete units of measurement, organized by type. These units of measurement are typically no longer used, though some may be in limited use in various regions. For units of measurement that are unusual but not necessarily obsolete, see List of unusual units of measurement. For units of measurement that are humorous in nature, see List of humorous units of measurement. Area * Antsingae – a unit of area, smaller than the bunarium. * Bunarium (plural "bunaria") – a unit of area, equal to about 120 Hectare#Are, ares or 12,000 square metres * Carucate * Cawnie * Decimal (unit), Decimal * Dessiatin * Ground (unit), Ground * Hide (unit), Hide * Juchart * Jugerum * Katha (unit), Katha * Lessa (unit), Lessa or Lecha * Marabba * Morgen * Oxgang * Pari (unit), Pari – a unit of area equal to about 1 hectare * Quinaria * Tathe * Virgate Energy, etc. * Poncelet – unit of power * Sthène – unit of force * * Length * Ald (unit), Ald * Alen (unit of length), Al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Candela
The candela (symbol: cd) is the unit of luminous intensity in the International System of Units (SI). It measures luminous power per unit solid angle emitted by a light source in a particular direction. Luminous intensity is analogous to radiant intensity, but instead of simply adding up the contributions of every wavelength of light in the source's spectrum, the contribution of each wavelength is weighted by the luminous efficiency function, the model of the sensitivity of the human eye to different wavelengths, standardized by the CIE and ISO. A common wax candle emits light with a luminous intensity of roughly one candela. If emission in some directions is blocked by an opaque barrier, the emission would still be approximately one candela in the directions that are not obscured. The word ''candela'' is Latin for ''candle''. The old name "candle" is still sometimes used, as in '' foot-candle'' and the modern definition of '' candlepower''. Definition The 26th General C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoflash Bomb
Flashbombs are loaded into a photo-reconnaissance Melsbroek, Belgium. c.1944 A photoflash bomb, or flash bomb, is bomb">explosive ordnance dropped by aircraft, usually military surveillance aircraft, designed to detonate Air burst">above ground to create an extremely bright flash of light. These bombs, which are capable of producing light at an intensity of up to hundreds of millions of candlepower, assist surveillance aircraft in taking nighttime Aerial photographic reconnaissance, aerial photos without the need to fly low to the ground which would make them vulnerable to possible enemy detection. Due to the advent of better nighttime optics, satellite imagery, and stealth aircraft, these bombs are no longer used by the military. Construction There were several models of photoflash bombs, but most had a similar construction and makeup. For example, the M23A1 was constructed of a cardboard tube, capped on both ends with metal "plugs." The tube was then filled with a flash po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Headlamp
A headlamp is a lamp attached to the front of a vehicle to illuminate the road ahead. Headlamps are also often called headlights, but in the most precise usage, ''headlamp'' is the term for the device itself and ''headlight'' is the term for the beam of light produced and distributed by the device. Headlamp performance has steadily improved throughout the automobile age, spurred by the great disparity between daytime and nighttime traffic fatalities: the US National Highway Traffic Safety Administration states that nearly half of all traffic-related fatalities occur in the dark, despite only 25% of traffic travelling during darkness. Other vehicles, such as trains and aircraft, are required to have headlamps. Bicycle headlamps are often used on bicycles, and are required in some jurisdictions. They can be powered by a battery or a small generator like a bottle or hub dynamo. History of automotive headlamps Origins The first horseless carriages used carriage lamps, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
California Vehicle Code
The California Vehicle Code, informally referred to as the Veh. Code or the CVC, is a legal code which contains almost all statutes relating to the operation, ownership and registration of vehicles (including bicycles and even animals when riding on a public roadway) in the state of California in the United States. It is one of the 29 California Codes enacted by the California State Legislature. The Vehicle Code's "Rules of the Road" generally apply to operating vehicles, bicycles, and animals on a public roadway, except for provisions which by their very nature can have no application. The Vehicle Code also contains statutes concerning the California Department of Motor Vehicles and the California Highway Patrol. The Vehicle Code includes various topics from defining the size of license plates to criminal law sections relating to the theft and misuse of motor vehicles. The Vehicle Code is one of 29 codes containing general statutes adopted by the California legislature and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inverse Square Law
In science, an inverse-square law is any scientific law stating that the observed "intensity" of a specified physical quantity is inversely proportional to the square of the distance from the source of that physical quantity. The fundamental cause for this can be understood as geometric dilution corresponding to point-source radiation into three-dimensional space. Radar energy expands during both the signal transmission and the reflected return, so the inverse square for both paths means that the radar will receive energy according to the inverse fourth power of the range. To prevent dilution of energy while propagating a signal, certain methods can be used such as a waveguide, which acts like a canal does for water, or how a gun barrel restricts hot gas expansion to one dimension in order to prevent loss of energy transfer to a bullet. Formula In mathematical notation the inverse square law can be expressed as an intensity (I) varying as a function of distance (d) from so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platinum
Platinum is a chemical element; it has Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name originates from Spanish language, Spanish , a diminutive of "silver". Platinum is a member of the platinum group of elements and group 10 element, group 10 of the periodic table of elements. It has six naturally occurring isotopes. It is one of the Abundance of elements in Earth's crust, rarer elements in Earth's crust, with an average abundance of approximately 5 microgram, μg/kg, making platinum about 30 times rarer than gold. It occurs in some nickel and copper ores along with some Native element mineral, native deposits, with 90% of current production from deposits across Russia's Ural Mountains, Colombia, the Sudbury Basin, Sudbury basin of Canada, and a large reserve in South Africa. Because of its scarcity in Earth's crust, only a f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
