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Visible Spectrum
The visible spectrum is the band 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). 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, known collectively as ''optical radiation''. 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 spectrum does not contain all the colors that the human visual system can distinguish. '' Unsaturated colors'' such as pink, or purple va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Dispersion Of A Mercury-vapor Lamp With A Flint Glass Prism IPNr°0125
Light or visible light is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequency, frequencies of 750–420 terahertz (unit), terahertz, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths). In physics, the term "light" may refer more broadly to electromagnetic radiation of any wavelength, whether visible or not. In this sense, gamma rays, X-rays, microwaves and radio waves are also light. The primary properties of light are intensity (physics), intensity, propagation direction, frequency or wavelength spectrum and polarization (waves), polarization. Its speed of light, speed in a vacuum, 299 792 458 metres a second (m/s), is one of the fundamental physical constant, constants of nature. Like all types of electromagnetic radiation, visible light propagates by massless elementary par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Purple
Purple is any of a variety of colors with hue between red and blue. In the RGB color model used in computer and television screens, purples are produced by mixing red and blue light. In the RYB color model historically used by painters, purples are created with a combination of red and blue pigments. In the CMYK color model used in printing, purples are made by combining magenta pigment with either cyan pigment, black pigment, or both. Purple has long been associated with royalty, originally because Tyrian purple dye, made from the mucus secretion of a species of snail, was extremely expensive in antiquity. Purple was the color worn by Roman magistrates; it became the imperial color worn by the rulers of the Byzantine Empire and the Holy Roman Empire, and later by Roman Catholic bishops. Similarly in Japan, the color is traditionally associated with the emperor and aristocracy. According to contemporary surveys in Europe and the United States, purple is the color most ofte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Opticks
''Opticks: or, A Treatise of the Reflexions, Refractions, Inflexions and Colours of Light'' is a book by English natural philosopher Isaac Newton that was published in English in 1704 (a scholarly Latin translation appeared in 1706). (''Opticks'' was originally published in 1704). The book analyzes the fundamental nature of light by means of the refraction of light with prisms and lenses, the diffraction of light by closely spaced sheets of glass, and the behaviour of color mixtures with spectral lights or pigment powders. ''Opticks'' was Newton's second major book on physical science and it is considered one of the three major works on optics during the Scientific Revolution (alongside Kepler's ''Astronomiae Pars Optica'' and Huygens' ''Traité de la Lumière''). Newton's name did not appear on the title page of the first edition of ''Opticks''. Overview The publication of ''Opticks'' represented a major contribution to science, different from but in some ways rivalling the ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isaac Newton
Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, physicist, astronomer, alchemist, theologian, and author (described in his time as a "natural philosopher"), widely recognised as one of the greatest mathematicians and physicists and among the most influential scientists of all time. He was a key figure in the philosophical revolution known as the Enlightenment. His book (''Mathematical Principles of Natural Philosophy''), first published in 1687, established classical mechanics. Newton also made seminal contributions to optics, and shares credit with German mathematician Gottfried Wilhelm Leibniz for developing infinitesimal calculus. In the , Newton formulated the laws of motion and universal gravitation that formed the dominant scientific viewpoint for centuries until it was superseded by the theory of relativity. Newton used his mathematical description of gravity to derive Kepler's laws of planetary motion, account for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rainbow
A rainbow is a meteorological phenomenon that is caused by reflection, refraction and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. It takes the form of a multicoloured circular arc. Rainbows caused by sunlight always appear in the section of sky directly opposite the Sun. Rainbows can be full circles. However, the observer normally sees only an arc formed by illuminated droplets above the ground, and centered on a line from the Sun to the observer's eye. In a primary rainbow, the arc shows red on the outer part and violet on the inner side. This rainbow is caused by light being refracted when entering a droplet of water, then reflected inside on the back of the droplet and refracted again when leaving it. In a double rainbow, a second arc is seen outside the primary arc, and has the order of its colours reversed, with red on the inner side of the arc. This is caused by the light being reflected twice on the inside of the drop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roger Bacon
Roger Bacon (; la, Rogerus or ', also '' Rogerus''; ), also known by the scholastic accolade ''Doctor Mirabilis'', was a medieval English philosopher and Franciscan friar who placed considerable emphasis on the study of nature through empiricism. In the early modern era, he was regarded as a wizard and particularly famed for the story of his mechanical or necromantic brazen head. He is sometimes credited (mainly since the 19th century) as one of the earliest European advocates of the modern scientific method, along with his teacher Robert Grosseteste. Bacon applied the empirical method of Ibn al-Haytham (Alhazen) to observations in texts attributed to Aristotle. Bacon discovered the importance of empirical testing when the results he obtained were different from those that would have been predicted by Aristotle. His linguistic work has been heralded for its early exposition of a universal grammar, and 21st-century re-evaluations emphasise that Bacon was essentially a medi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectral Color
A spectral color is a color that is evoked by ''monochromatic light'', i.e. either a single wavelength of light in the visible spectrum, or by a relatively narrow band of wavelengths (e.g. lasers). Every wavelength of visible light is perceived as a spectral color; when viewed as a continuous spectrum, these colors are seen as the familiar rainbow. All colors that do not qualify as a spectral color are called ''non-spectral colors'' or ''extra-spectral colors''. Extra-spectral colors cannot be evoked with a single wavelength of light, but rather by a combination of wavelengths. Likewise, light comprising several wavelengths cannot evoke a spectral color. In color spaces In color spaces which include all, or most spectral colors, they form a part of boundary of the set of all real colors. When considering a three-dimensional color space (which including luminance), the spectral colors form a surface. When excluding luminance and considering a two-dimensional color space (c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monochromatic Light
{{Short description, Electromagnetic radiation with a single constant frequency In physics, monochromatic radiation is electromagnetic radiation with a single constant frequency. When that frequency is part of the visible spectrum (or near it) the term monochromatic light is often used. Monochromatic light is perceived by the human eye as a spectral color. When monochromatic radiation propagates through vacuum or a homogeneous transparent medium, it has a single constant wavelength. Practical monochromaticity No radiation can be totally monochromatic, since that would require a wave of infinite duration as a consequence of the Fourier transform's localization property (cf. spectral coherence). In practice, "monochromatic" radiation — even from lasers or spectral lines — always consists of components with a range of frequencies of non-zero width. Generation Monochromatic radiation can be produced by a number of methods. Isaac Newton observed that a beam of light from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Near Infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around 1 millimeter (300 GHz) to the nominal red edge of the visible spectrum, around 700 nanometers (430 THz). Longer IR wavelengths (30 μm-100 μm) are sometimes included as part of the terahertz radiation range. Almost all black-body radiation from objects near room temperature is at infrared wavelengths. As a form of electromagnetic radiation, IR propagates energy and momentum, exerts radiation pressure, and has properties corresponding to both those of a wave and of a particle, the photon. It was long known that fires emit invisible heat; in 1681 the pioneering experimenter Edme Mariotte showed that glass, though transparent to sunlight, obstructed radiant heat. In 1800 the astronomer Sir William Herschel discovered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scattering
Scattering is a term used in physics to describe a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including particles and radiation) in the medium through which they pass. In conventional use, this also includes deviation of reflected radiation from the angle predicted by the law of reflection. Reflections of radiation that undergo scattering are often called ''diffuse reflections'' and unscattered reflections are called ''specular'' (mirror-like) reflections. Originally, the term was confined to light scattering (going back at least as far as Isaac Newton in the 17th century). As more "ray"-like phenomena were discovered, the idea of scattering was extended to them, so that William Herschel could refer to the scattering of "heat rays" (not then recognized as electromagnetic in nature) in 1800. John Tyndall, a pioneer in light scattering researc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Window
The optical window is a range of wavelengths that are not blocked by the earth's atmosphere. The window runs from around 300 nanometers ( ultraviolet-B) up into the range the human eye can detect, roughly 400–700 nm and continues up to approximately 2 μm. Sunlight mostly reaches the ground through the optical atmospheric window; the sun is particularly active in most of this range (44% of the radiation emitted by the sun falls within the visible spectrum and 49% falls within the infrared spectrum). Definition The earth's atmosphere is not totally transparent and is in fact 100% opaque to many wavelengths (see plot of Earth's opacity); the wavelength ranges to which it is transparent are called atmospheric windows. Disambiguation of the term 'optical spectrum' Although the word ''optical'', deriving from Ancient Greek ὀπτῐκός (optikós, “of or for sight”), generally refers to something visible or visual, the term ''optical spectrum'' is used to describe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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