A report on Light and Visible spectrum

A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) are separated.
White light is dispersed by a prism into the colors of the visible spectrum.
The electromagnetic spectrum, with the visible portion highlighted
Laser beams with visible spectrum
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Newton's color circle, from Opticks of 1704, showing the colors he associated with musical notes. The spectral colors from red to violet are divided by the notes of the musical scale, starting at D. The circle completes a full octave, from D to D. Newton's circle places red, at one end of the spectrum, next to violet, at the other. This reflects the fact that non-spectral purple colors are observed when red and violet light are mixed.
Beam of sun light inside the cavity of Rocca ill'Abissu at Fondachelli-Fantina, Sicily
Newton's observation of prismatic colors (David Brewster 1855)
Due to refraction, the straw dipped in water appears bent and the ruler scale compressed when viewed from a shallow angle.
How visible light interacts with objects to make them colorful
Hong Kong illuminated by colourful artificial lighting.
Approximation of spectral colors on a display results in somewhat distorted chromaticity
Pierre Gassendi.
Earth's atmosphere partially or totally blocks some wavelengths of electromagnetic radiation, but in visible light it is mostly transparent
Christiaan Huygens.
Thomas Young's sketch of a double-slit experiment showing diffraction. Young's experiments supported the theory that light consists of waves.
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Electromagnetic radiation in this range of wavelengths is called visible light or simply light.

- Visible spectrum

Generally, electromagnetic radiation (EMR) is classified by wavelength into radio waves, microwaves, infrared, the visible spectrum that we perceive as light, ultraviolet, X-rays and gamma rays.

- Light
A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) are separated.

9 related topics with Alpha

Overall

The electromagnetic spectrum

Electromagnetic spectrum

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Range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies.

Range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies.

The electromagnetic spectrum
A diagram of the electromagnetic spectrum, showing various properties across the range of frequencies and wavelengths
Plot of Earth's atmospheric opacity to various wavelengths of electromagnetic radiation. This is the surface-to-space opacity, the atmosphere is transparent to longwave radio transmissions within the troposphere but opaque to space due to the ionosphere.
Plot of atmospheric opacity for terrestrial to terrestrial transmission showing the molecules responsible for some of the resonances
The amount of penetration of UV relative to altitude in Earth's ozone

This frequency range is divided into separate bands, and the electromagnetic waves within each frequency band are called by different names; beginning at the low frequency (long wavelength) end of the spectrum these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays at the high-frequency (short wavelength) end.

The wavelength of UV rays is shorter than the violet end of the visible spectrum but longer than the X-ray.

A pseudocolor image of two people taken in long-wavelength infrared (body-temperature thermal) radiation.

Infrared

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A pseudocolor image of two people taken in long-wavelength infrared (body-temperature thermal) radiation.
This false-color infrared space telescope image has blue, green and red corresponding to 3.4, 4.6, and 12 μm wavelengths, respectively.
Plot of atmospheric transmittance in part of the infrared region
Materials with higher emissivity appear closer to their true temperature than materials that reflect more of their different-temperature surroundings. In this thermal image, the more reflective ceramic cylinder, reflecting the cooler surroundings, appears to be colder than its cubic container (made of more emissive silicon carbide), while in fact, they have the same temperature.
Active-infrared night vision: the camera illuminates the scene at infrared wavelengths invisible to the human eye. Despite a dark back-lit scene, active-infrared night vision delivers identifying details, as seen on the display monitor.
Thermography helped to determine the temperature profile of the Space Shuttle thermal protection system during re-entry.
Hyperspectral thermal infrared emission measurement, an outdoor scan in winter conditions, ambient temperature −15 °C, image produced with a Specim LWIR hyperspectral imager. Relative radiance spectra from various targets in the image are shown with arrows. The infrared spectra of the different objects such as the watch clasp have clearly distinctive characteristics. The contrast level indicates the temperature of the object.
Infrared light from the LED of a remote control as recorded by a digital camera
Reflected light photograph in various infrared spectra to illustrate the appearance as the wavelength of light changes.
Infrared hair dryer for hair salons, c. 2010s
IR satellite picture of cumulonimbus clouds over the Great Plains of the United States.
The greenhouse effect with molecules of methane, water, and carbon dioxide re-radiating solar heat
Beta Pictoris with its planet Beta Pictoris b, the light-blue dot off-center, as seen in infrared. It combines two images, the inner disc is at 3.6 μm.
An infrared reflectogram of Mona Lisa by Leonardo da Vinci
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Thermographic image of a snake eating a mouse
Infrared radiation was discovered in 1800 by William Herschel.
Infrared hair dryer for hair salons, c. 2010s

Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light.

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).

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Electromagnetic radiation

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In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, propagating through space, carrying electromagnetic radiant energy.

In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, propagating through space, carrying electromagnetic radiant energy.

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Shows the relative wavelengths of the electromagnetic waves of three different colours of light (blue, green, and red) with a distance scale in micrometers along the x-axis.
In electromagnetic radiation (such as microwaves from an antenna, shown here) the term "radiation" applies only to the parts of the electromagnetic field that radiate into infinite space and decrease in intensity by an inverse-square law of power, so that the total radiation energy that crosses through an imaginary spherical surface is the same, no matter how far away from the antenna the spherical surface is drawn. Electromagnetic radiation thus includes the far field part of the electromagnetic field around a transmitter. A part of the "near-field" close to the transmitter, forms part of the changing electromagnetic field, but does not count as electromagnetic radiation.
Electromagnetic waves can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. This 3D animation shows a plane linearly polarized wave propagating from left to right. The electric and magnetic fields in such a wave are in-phase with each other, reaching minima and maxima together.
Representation of the electric field vector of a wave of circularly polarized electromagnetic radiation.
James Clerk Maxwell
Electromagnetic spectrum with visible light highlighted
Rough plot of Earth's atmospheric absorption and scattering (or opacity) of various wavelengths of electromagnetic radiation

It includes radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, and gamma rays.

EM radiation (the designation 'radiation' excludes static electric and magnetic and near fields) is classified by wavelength into radio, microwave, infrared, visible, ultraviolet, X-rays and gamma rays.

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Sun

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Star at the center of the Solar System.

Star at the center of the Solar System.

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Illustration of the Sun's structure, in false color for contrast
Illustration of a proton-proton reaction chain, from hydrogen forming deuterium, helium-3, and regular helium-4.
Illustration of different stars's internal structure, the Sun in the middle has an inner radiating zone and an outer convective zone.
High-resolution image of the Sun's surface taken by the Daniel K. Inouye Solar Telescope (DKIST)
During a total solar eclipse, the solar corona can be seen with the naked eye, during the brief period of totality.
The Sun's transition region taken by Hinode's Solar Optical Telescope
Sunlight and glare seen overlooking from the International Space Station
Once outside the Sun's surface, neutrinos and photons travel at the speed of light
Visible light photograph of sunspot
Measurements from 2005 of solar cycle variation during the previous 30 years
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The size of the current Sun (now in the main sequence) compared to its estimated size during its red-giant phase in the future
The Solar System, with sizes of the Sun and planets to scale. The terrestrial planets are on the right, the gas and ice giants are on the left.
The Trundholm sun chariot pulled by a horse is a sculpture believed to be illustrating an important part of Nordic Bronze Age mythology.
Sol, the Sun, from a 1550 edition of Guido Bonatti's Liber astronomiae.
False-color image taken in 2010 as seen in 30.4-nanometer ultraviolet light wavelength
A false-color of a coronal hole on the Sun forming a question mark (22 December 2017)
A false-color solar prominence erupts in August 2012, as captured by the Solar Dynamics Observatory
The Sun seen from Earth, with glare from the lenses. The eye also see glare when looked towards the Sun directly.
Sun and Immortal Birds Gold Ornament by ancient Shu people. The center is a sun pattern with twelve points around which four birds fly in the same counterclockwise direction, Shang dynasty

It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy mainly as light, ultraviolet, and infrared radiation.

During early studies of the optical spectrum of the photosphere, some absorption lines were found that did not correspond to any chemical elements then known on Earth.

The wavelength of a sine wave, λ, can be measured between any two points with the same phase, such as between crests (on top), or troughs (on bottom), or corresponding zero crossings as shown.

Wavelength

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Spatial period of a periodic wave—the distance over which the wave's shape repeats.

Spatial period of a periodic wave—the distance over which the wave's shape repeats.

The wavelength of a sine wave, λ, can be measured between any two points with the same phase, such as between crests (on top), or troughs (on bottom), or corresponding zero crossings as shown.
Sinusoidal standing waves in a box that constrains the end points to be nodes will have an integer number of half wavelengths fitting in the box.
A standing wave (black) depicted as the sum of two propagating waves traveling in opposite directions (red and blue)
Wavelength is decreased in a medium with slower propagation.
Refraction: upon entering a medium where its speed is lower, the wave changes direction.
Separation of colors by a prism (click for animation)
Various local wavelengths on a crest-to-crest basis in an ocean wave approaching shore
A sinusoidal wave travelling in a nonuniform medium, with loss
A wave on a line of atoms can be interpreted according to a variety of wavelengths.
Near-periodic waves over shallow water
Wavelength of a periodic but non-sinusoidal waveform.
A propagating wave packet
Pattern of light intensity on a screen for light passing through two slits. The labels on the right refer to the difference of the path lengths from the two slits, which are idealized here as point sources.
Diffraction pattern of a double slit has a single-slit envelope.
Relationship between wavelength, angular wavelength, and other wave properties.

Examples of waves are sound waves, light, water waves and periodic electrical signals in a conductor.

The name originated with the visible light spectrum but now can be applied to the entire electromagnetic spectrum as well as to a sound spectrum or vibration spectrum.

The Sun, as seen from low Earth orbit overlooking the International Space Station. This sunlight is not filtered by the lower atmosphere, which blocks much of the solar spectrum.

Sunlight

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The Sun, as seen from low Earth orbit overlooking the International Space Station. This sunlight is not filtered by the lower atmosphere, which blocks much of the solar spectrum.
Sunrise over the Gulf of Mexico and Florida. Taken on 20 October 1968 from Apollo 7.
Sunlight on Mars is dimmer than on Earth. This photo of a Martian sunset was imaged by Mars Pathfinder.
Solar irradiance spectrum at top of atmosphere, on a linear scale and plotted against wavenumber
Sunlight shining through clouds, giving rise to crepuscular rays
Spectrum of the visible wavelengths at approximately sea level; illumination by direct sunlight compared with direct sunlight scattered by cloud cover and with indirect sunlight by varying degrees of cloud cover. The yellow line shows the power spectrum of direct sunlight under optimal conditions. To aid comparison, the other illumination conditions are scaled by the factor shown in the key so they match at about 470 nm (blue light).
Sunlight penetrating through a forest canopy in Germany
Édouard Manet: Le déjeuner sur l'herbe (1862-63)
Téli verőfény ("Winter Sunshine") by László Mednyánszky, early 20th century
Sun bathers in Finland

Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light.

When direct solar radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and radiant heat.

The visual dorsal stream (green) and ventral stream (purple) are shown. Much of the human cerebral cortex is involved in vision.

Visual perception

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The visual dorsal stream (green) and ventral stream (purple) are shown. Much of the human cerebral cortex is involved in vision.
Leonardo da Vinci: The eye has a central line and everything that reaches the eye through this central line can be seen distinctly.
Eye movement first 2 seconds (Yarbus, 1967)

Visual perception is the ability to interpret the surrounding environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the visible spectrum reflected by objects in the environment.

The human visual system is generally believed to be sensitive to visible light in the range of wavelengths between 370 and 730 nanometers (0.00000037 to 0.00000073 meters) of the electromagnetic spectrum.

Pencils shown in various colors

Color

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Visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes.

Visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes.

Pencils shown in various colors
Continuous optical spectrum rendered into the sRGB color space.
The upper disk and the lower disk have exactly the same objective color, and are in identical gray surroundings; based on context differences, humans perceive the squares as having different reflectances, and may interpret the colors as different color categories; see checker shadow illusion.
Normalized typical human cone cell responses (S, M, and L types) to monochromatic spectral stimuli
The visual dorsal stream (green) and ventral stream (purple) are shown. The ventral stream is responsible for color perception.
This picture contains one million pixels, each one a different color
The CIE 1931 color space xy chromaticity diagram with the visual locus plotted using the CIE (2006) physiologically-relevant LMS fundamental color matching functions transformed into the CIE 1931 xy color space and converted into Adobe RGB. The triangle shows the gamut of Adobe RGB. The Planckian locus is shown with color temperatures labeled in Kelvins. The outer curved boundary is the spectral (or monochromatic) locus, with wavelengths shown in nanometers. Note that the colors in this file are being specified using Adobe RGB. Areas outside the triangle cannot be accurately rendered since they are outside the gamut of Adobe RGB, therefore they have been interpreted. Note that the colors depicted depend on the gamut and color accuracy of your display.
Additive color mixing: combining red and green yields yellow; combining all three primary colors together yields white.
Subtractive color mixing: combining yellow and magenta yields red; combining all three primary colors together yields black
Twelve main pigment colors

It includes the perception of color by the human eye and brain, the origin of color in materials, color theory in art, and the physics of electromagnetic radiation in the visible range (that is, what is commonly referred to simply as light).

When the wavelength is within the visible spectrum (the range of wavelengths humans can perceive, approximately from 390 nm to 700 nm), it is known as "visible light".

Absorption lines for air, under indirect illumination, with the direct light source not visible, so that the gas is not directly between source and detector. Here, Fraunhofer lines in sunlight and Rayleigh scattering of this sunlight is the "source." This is the spectrum of a blue sky somewhat close to the horizon, pointing east at around 3 or 4 pm (i.e., Sun toward the west) on a clear day.

Spectral line

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Absorption lines for air, under indirect illumination, with the direct light source not visible, so that the gas is not directly between source and detector. Here, Fraunhofer lines in sunlight and Rayleigh scattering of this sunlight is the "source." This is the spectrum of a blue sky somewhat close to the horizon, pointing east at around 3 or 4 pm (i.e., Sun toward the west) on a clear day.
Continuous spectrum of an incandescent lamp (mid) and discrete spectrum lines of a fluorescent lamp (bottom)

A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies.

Strong spectral lines in the visible part of the spectrum often have a unique Fraunhofer line designation, such as K for a line at 393.366 nm emerging from singly-ionized Ca+, though some of the Fraunhofer "lines" are blends of multiple lines from several different species.