The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 380 to about 750 nanometers. In terms of frequency, this corresponds to a band in the vicinity of 400–790 terahertz. These boundaries are not sharply defined and may vary per individual. Under optimal conditions these limits of human perception can extend to 310 nm (ultraviolet) and 1100 nm (near infrared). The optical spectrum is sometimes considered to be the same as the visible spectrum, but some authors define the term more broadly, to include the ultraviolet and infrared parts of the electromagnetic spectrum as well.The spectrum does not contain all the colors that the human visual system can distinguish. Unsaturated colors such as pink, or purple variations like magenta, for example, are absent because they can only be made from a mix of multiple wavelengths. Colors containing only one wavelength are also called pure colors or spectral colors.Visible wavelengths pass largely unattenuated through the Earths atmosphere via the optical window region of the electromagnetic spectrum. An example of this phenomenon is when clean air scatters blue light more than red light, and so the midday sky appears blue (apart from the area around the sun which appears white because the light is not scattered as much). The optical window is also referred to as the visible window because it overlaps the human visible response spectrum. The near infrared (NIR) window lies just out of the human vision, as well as the medium wavelength infrared (MWIR) window, and the long-wavelength or far-infrared (LWIR or FIR) window, although other animals may perceive them.
Posts made by MiguelANymn
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RE: visible spectrum
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totalitarian state
a government that subordinates the individual to the state and strictly controls all aspects of life by coercive measures
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RE: fiddle with
To manipulate an object, especially in a nervous or restless manner.
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brush kangaroo
any of various small or medium-sized kangaroos; often brightly colored
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myocardial infarct
destruction of heart tissue resulting from obstruction of the blood supply to the heart muscle
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RE: four-party
A four-party system or situation refers to an arrangement, negotiation or system in which four distinct groups, entities or individuals are involved, each representing their own interests. This term is often used in the context of political systems where there are four major political parties, but can also be used in other contexts such as business or legal negotiations where four main parties are involved.
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RE: arteria carotis
The arteria carotis, also known as the carotid artery, is one of the major arteries in the human body that supplies blood to the head and neck. It originates from the aorta in the chest, branches up through the side of the neck, and further divides into two main sections - the internal carotid artery, supplying blood to the brain, and the external carotid artery, supplying blood to the face and scalp. Its an essential part of the vascular system due to its role in delivering oxygenated blood to the brain.
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RE: tower of pharos
The Tower of Pharos is also known as the Lighthouse of Alexandria and was one of the Seven Wonders of the Ancient World. It was located on the island of Pharos in Alexandria, Egypt. Built in the 3rd century BC, it was the tallest man-made structure in the world for many centuries and served as a navigational aid for ships entering Alexandrias harbor.
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bangalore torpedo
a metal pipe filled with explosive, used to detonate land mines or to clear a path through barbed wire
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RE: tussock
tus′ok, n. a tuft of grass or twigs.—ns. Tuss′ock-grass, a large grass of the same genus with the Cocks-foot Grass of Britain, native to the Falkland Islands, remarkable for forming great tufts—also Tuss′ac-grass; Tuss′ock-moth, a grayish-white moth about an inch long, the caterpillars of which do great mischief in hop-grounds, and are known as Hop-dogs.—adj. Tuss′ocky, abounding in tufts. [Perh. conn. with obs. tusk, a tuft; cf. Dan. dusk.]
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RE: black grama
Bouteloua eriopoda, commonly known as black grama, is a perennial prairie grass that is native to the Southwestern United States. Its main means of reproduction is by stolons, as its ratio of viable seeds to sterile ones is naturally low. The disparity may play a role in its lack of tolerance to overgrazing (relative to other grasses), but aside from this B. eriopoda is a good forage food for livestock.
It was first described, as Chondrosum eriopodum, in 1848 from specimens collected along and nearby the Del Norte river in New Mexico. -
common matrimony vine
deciduous erect or spreading shrub with spiny branches and violet-purple flowers followed by orange-red berries; southeastern Europe to China
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RE: Zither
A zither is a musical instrument of the string family, typically composed of a flat wooden body with numerous strings stretched across it. It is played by strumming or plucking the strings with the fingers or a plectrum, often while the instrument rests on a table or on the players lap. The sound is produced by the strings vibrations resonating within the body of the instrument. Zithers are common in many forms of folk music, particularly in Europe and Asia.
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RE: Casco
kas′kō, n. a form of boat used at Manila for lading and unlading ships.