The visible spectrum (or sometimes called the optical spectrum) is the portion of the electromagnetic spectrum that is visible to (can be detected by) the human eye. The electromagnetic (EM spectrum is the range of all possible Electromagnetic radiation frequencies In Psychology, visual perception is the ability to interpret information from Visible light reaching the Eyes The resulting Perception is also Eyes are organs that detect Light, and send signals along the Optic nerve to the visual areas of the brain Electromagnetic radiation in this range of wavelengths is called visible light or simply light. Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 A typical human eye will respond to wavelengths in air from about 380 to 750 nm. Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five [1] The corresponding wavelengths in water and other media are reduced by a factor equal to the refractive index. Water is a common Chemical substance that is essential for the survival of all known forms of Life. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium In terms of frequency, this corresponds to a band in the vicinity of 400–790 terahertz. Electromagnetic waves sent at terahertz frequencies, known as terahertz radiation, submillimeter radiation, terahertz waves, terahertz A light-adapted eye generally has its maximum sensitivity at around 555 nm (540 THz), in the green region of the optical spectrum (see: luminosity function). Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 A nanometre ( American spelling: nanometer, symbol nm) ( Greek: νάνος nanos dwarf; μετρώ metrό count) is a Green is a Color, the perception of which is evoked by light having a spectrum dominated by energy with a Wavelength of roughly 520–570- nm. The luminosity function or luminous efficiency function describes the average sensitivity of the human Eye to light of different wavelengths The spectrum does not, however, contain all the colors that the human eyes and brain can distinguish. Unsaturated colors such as pink, and purple colors such as magenta are absent, for example, because they can only be made by a mix of multiple wavelengths. Pink is a pale Red Color that was first recorded in the 17th century to describe the pale red Flowers of pinks, Flowering plants Purple is a general term for the range of shades of Color occurring between Red and Blue. Magenta is a purplish red Color evoked by lights with less power in yellowish-green Wavelengths than in blue and red wavelengths ( complements of magenta have
Wavelengths visible to the eye also pass through the "optical window", the region of the electromagnetic spectrum which passes largely unattenuated through the Earth's atmosphere (although blue light is scattered more than red light, which is the reason the sky appears blue). The meaning of this term depends on the context In Astronomy, the optical window is the optical portion of the Electromagnetic spectrum that passes through Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five Scattering is a general physical process whereby some forms of Radiation, such as Light, Sound or moving particles for example are forced to deviate from The response of the human eye is defined by subjective testing (see CIE), but the atmospheric windows are defined by physical measurement. Established in 1913 and based in Vienna, Austria, the International Commission on Illumination (usually known as the CIE for its French name Commission The "visible window" is so called because it overlaps the human visible response spectrum; the near infrared (NIR) windows lie just out of human response window, and the Medium Wavelength IR (MWIR) and Long Wavelength or Far Infrared (LWIR or FIR) are far beyond the human response region.
The eyes of many species perceive wavelengths different from the spectrum visible to the human eye. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. For example, many insects, such as bees, can see light in the ultraviolet, which is useful for finding nectar in flowers. Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described Bees are flying Insects closely related to Wasps and Ants Bees are a Monophyletic lineage within the superfamily Apoidea Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays Nectar is a Sugar -rich liquid produced by plants It is produced either by the Flowers in which it attracts pollinating animals or by extrafloral A flower, also known as a bloom or Blossom, is the reproductive structure found in Flowering plants (plants of the division Magnoliophyta, also For this reason, plant species whose life cycles are linked to insect pollination may owe their reproductive success to their appearance in ultraviolet light, rather than how colorful they appear to our eyes.
In humans, much of the ultraviolet light which enters the eye is blocked by the eye's lens from reaching the light-sensitive retina. People who have had cataract surgery, in which the lenses of their eyes are removed and replaced with plastic lenses, can see light in the ultraviolet, which is why such individuals often prefer to wear ultraviolet blocking sunglasses when outside on a bright day.
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History
Two of the earliest explanations of the optical spectrum came from Isaac Newton, when he wrote his Opticks, and from Goethe, in his Theory of Colours, although earlier observations had been made by Roger Bacon who first recognized the visible spectrum in a glass of water, four centuries before Newton discovered that prisms could disassemble and reassemble white light. Sir Isaac Newton, FRS (ˈnjuːtən 4 January 1643 31 March 1727) Biography Early years See also Isaac Newton's early life and achievements Opticks is a book written by English physicist Isaac Newton that was released to the public in 1704. ˈjoːhan ˈvɔlfgaŋ fɔn ˈgøːtə (in English generally ˈgɝːtə 28 August 1749 22 March 1832 was a German writer Theory of Colours (original German title Zur Farbenlehre) is a book by Johann Wolfgang von Goethe published in 1810 For the Nova Scotia premier see Roger Bacon (politician. Roger Bacon, O [2]
Newton first used the word spectrum (Latin for "appearance" or "apparition") in print in 1671 in describing his experiments in optics. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. In scientific inquiry an experiment ( Latin: Ex- periri, "to try out" is a method of investigating particular types of research questions or Newton observed that, when a narrow beam of sunlight strikes the face of a glass prism at an angle, some is reflected and some of the beam passes into and through the glass, emerging as different colored bands. Sunlight, in the broad sense is the total spectrum of the Electromagnetic radiation given off by the Sun. Glass in the common sense refers to a Hard, Brittle, transparent Solid, such as that used for Windows many In Optics, a dispersive prism is a type of optical prism, normally having the shape of a geometrical triangular prism. In Geometry and Trigonometry, an angle (in full plane angle) is the figure formed by two rays sharing a common Endpoint, called Reflection is the change in direction of a Wave front at an interface between two different media so that the wave front returns into the medium from which Newton hypothesized that light was made up of "corpuscles" (particles) of different colors, and that the different colors of light moved at different speeds in transparent matter, with red light moving more quickly in glass than violet light. The result is that red light was bent (refracted) less sharply than violet light as it passed through the prism, creating a spectrum of colors. Refraction is the change in direction of a Wave due to a change in its Speed.
Newton divided the spectrum into seven named colors: red, orange, yellow, green, blue, indigo, and violet (this order being popularly memorised by schoolchildren using the mnemonic ROY G. BIV). Red is any of a number of similar Colors evoked by light consisting predominantly of the longest wavelengths of Light discernible by the human eye in the wavelength The colour orange occurs Yellow is the Color evoked by light that stimulates both the L and M (long and medium wavelength Cone cells of the Retina about equally Green is a Color, the perception of which is evoked by light having a spectrum dominated by energy with a Wavelength of roughly 520–570- nm. Blue is a Colour, the Perception of which is evoked by Indigo is the Color on the Electromagnetic spectrum between about 420 and 450 nm in Wavelength, placing it between Blue and violet As the name of a color violet (named after the flower violet) is used in two senses first referring to the color of Light at the short- Wavelength Roy G Biv is a Mnemonic for the sequence of hues in the Visible spectrum, in rainbows, and in order from longest to shortest wavelength He chose seven colors out of a belief, derived from the ancient Greek sophists, that there was a connection between the colors, the musical notes, the known objects in the solar system, and the days of the week. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. [3][4] The human eye is relatively insensitive to indigo's frequencies, and some otherwise well-sighted people cannot distinguish indigo from blue and violet. For this reason some commentators including Isaac Asimov have suggested that indigo should not be regarded as a color in its own right but merely as a shade of blue or violet. Isaac Asimov (c January 2 1920 &ndash April 6 1992 ˈaɪzək ˈæzɪmʌv originally Исаак Озимов but now transcribed into Russian as, was a Russian
Johann Wolfgang von Goethe contended that the continuous spectrum was a compound phenomenon. ˈjoːhan ˈvɔlfgaŋ fɔn ˈgøːtə (in English generally ˈgɝːtə 28 August 1749 22 March 1832 was a German writer Whereas Newton narrowed the beam of light in order to isolate the phenomenon, Goethe observed that with a wider aperture, there was no spectrum - rather there were reddish-yellow edges and blue-cyan edges with white between them, and the spectrum only arose when these edges came close enough to overlap. White is a Color, the perception which is evoked by Light that stimulates all three types of color sensitive Cone cells in the Human eye
All light travels at the same speed in a vacuum. This vacuum means "absence of matter" or "an empty area or space" for the cleaning appliance see Vacuum cleaner. The speed of light within a material is lower than the speed of light in a vacuum, and the ratio of speeds is known as the refractive index of the material. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium Because the refractive index (and thus the speed) of a wave in a material depends on its frequency (in accordance with a dispersion relation), light consisting of multiple frequencies—for instance white light—will be dispersed at the interface between the material and air or vacuum. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium Frequency is a measure of the number of occurrences of a repeating event per unit Time. Dispersion relations describe the ways that wave propagation varies with the Wavelength or Frequency of a wave. In Optics, dispersion is the phenomenon in which the Phase velocity of a wave depends on its frequency Both water and glass can be used to demonstrate dispersion; a glass prism yields an optical spectrum from white light, and rainbows are an ideal example of natural refraction of the visible spectrum. A rainbow is an optical and meteorological phenomenon that causes a spectrum of Light to appear in the Sky when the Sun
Spectral colors
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|
|---|---|
| Color | Wavelength |
| violet | 380–450 nm |
| blue | 450–495 nm |
| green | 495–570 nm |
| yellow | 570–590 nm |
| orange | 590–620 nm |
| red | 620–750 nm |
The familiar colors of the rainbow in the spectrum include all those colors that can be produced by visible light of a single wavelength only, the pure spectral or monochromatic colors. In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. As the name of a color violet (named after the flower violet) is used in two senses first referring to the color of Light at the short- Wavelength Blue is a Colour, the Perception of which is evoked by Green is a Color, the perception of which is evoked by light having a spectrum dominated by energy with a Wavelength of roughly 520–570- nm. Yellow is the Color evoked by light that stimulates both the L and M (long and medium wavelength Cone cells of the Retina about equally The colour orange occurs Red is any of a number of similar Colors evoked by light consisting predominantly of the longest wavelengths of Light discernible by the human eye in the wavelength A rainbow is an optical and meteorological phenomenon that causes a spectrum of Light to appear in the Sky when the Sun
Although the spectrum is continuous and therefore there are no clear boundaries between one color and the next, the ranges may be used as an approximation. [5]
Spectroscopy
The scientific study of objects based on the spectrum of the light they emit is called spectroscopy. Spectroscopy was originally the study of the interaction between Radiation and Matter as a function of Wavelength (λ One particularly important application of spectroscopy is in astronomy, where spectroscopy is essential for analysing the properties of distant objects. Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study Typically, astronomical spectroscopy utilises high-dispersion diffraction gratings to observe spectra at very high spectral resolutions. Astronomical spectroscopy is the technique of Spectroscopy used in Astronomy. In Optics, a Diffraction grating is an optical component with a regular pattern which splits ( diffracts) light into several beams travelling in different Helium was first detected through an analysis of the spectrum of the Sun; chemical elements can be detected in astronomical objects by emission lines and absorption lines; the shifting of spectral lines can be used to measure the redshift or blueshift of distant or fast-moving objects. Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical The Sun (Sol is the Star at the center of the Solar System. A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range compared A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range compared In Physics and Astronomy, redshift occurs when Electromagnetic radiation – usually Visible light – emitted or reflected by Blue shift is the shortening of a transmitted signal's Wavelength, and/or an increase in its Frequency, due to the Doppler Effect, which indicates that The first exoplanets to be discovered were found by analysing the doppler shift of stars at such a high resolution that variations in their radial velocity as small as a few metres per second could be detected: the presence of planets was revealed by their gravitational influence on the stars analysed, as revealed by their motion paths. An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312 Any Planet is an extremely faint light source compared to its parent Star. The Doppler effect (or Doppler shift) named after Christian Doppler, is the change in Frequency and Wavelength of a Wave for Radial velocity is the Velocity of an object in the direction of the line of sight (i Gravitation is a natural Phenomenon by which objects with Mass attract one another
Color display spectrum
Color displays (e. g. , computer monitors or televisions) mix red, green, and blue color to approximate the color spectrum. A visual display unit, often called simply a monitor or display, is a piece of Electrical equipment which displays images generated from the Video Television ( TV) is a widely used Telecommunication medium for sending ( Broadcasting) and receiving moving Images, either monochromatic Red is any of a number of similar Colors evoked by light consisting predominantly of the longest wavelengths of Light discernible by the human eye in the wavelength Green is a Color, the perception of which is evoked by light having a spectrum dominated by energy with a Wavelength of roughly 520–570- nm. Blue is a Colour, the Perception of which is evoked by In the illustration, the narrow red, green and blue bars show the relative mixture of these three colors used to produce the color directly above.
See also
References
- ^ Cecie Starr (2005). Color vision is the capacity of an organism or machine to distinguish objects based on the Wavelengths (or frequencies) of the Light they reflect or emit In Ophthalmology, high-energy visible light ( HEV light) is high-frequency light in the violet / Blue band from 380 to 530 nm in Theory of Colours (original German title Zur Farbenlehre) is a book by Johann Wolfgang von Goethe published in 1810 Biology: Concepts and Applications. Thomson Brooks/Cole. ISBN 053446226X.
- ^ Coffey, Peter (1912). The Science of Logic: An Inquiry Into the Principles of Accurate Thought. Longmans.
- ^ Hutchison, Niels (2004). Music For Measure: On the 300th Anniversary of Newton's Opticks. Colour Music. Retrieved on 2006-08-11. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 2492 BC - Traditional date of the defeat of Bel by Hayk, progenitor and founder of the Armenian nation
- ^ Newton, Isaac (1704). Sir Isaac Newton, FRS (ˈnjuːtən 4 January 1643 31 March 1727) Biography Early years See also Isaac Newton's early life and achievements Opticks. Opticks is a book written by English physicist Isaac Newton that was released to the public in 1704.
- ^ Thomas J. Bruno, Paris D. N. Svoronos. CRC Handbook of Fundamental Spectroscopic Correlation Charts. CRC Press, 2005.
Dictionary
visible spectrum
-noun
- (physics) The portion of the electromagnetic spectrum which is visible to the human eye.
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