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Encyclopedia > Electromagnetic spectrum
Although some radiations are marked as N for no in the diagram, some waves do in fact penetrate the atmosphere, although extremely minimally compared to the other radiations

The electromagnetic (EM) spectrum is the range of all possible electromagnetic radiation.[1] The "electromagnetic spectrum" (usually just spectrum) of an object is the characteristic distribution of electromagnetic radiation from that object. Image File history File links Question_book-3. ... Image File history File links Size of this preview: 800 Ã— 572 pixelsFull resolution (962 Ã— 688 pixel, file size: 108 KB, MIME type: image/jpeg) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Size of this preview: 800 Ã— 572 pixelsFull resolution (962 Ã— 688 pixel, file size: 108 KB, MIME type: image/jpeg) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... This box:      Electromagnetic (EM) radiation is a self-propagating wave in space with electric and magnetic components. ...

The electromagnetic spectrum extends from below the frequencies used for modern radio (at the long-wavelength end) through gamma radiation (at the short-wavelength end), covering wavelengths from thousands of kilometres down to a fraction the size of an atom. It's thought that the short wavelength limit is the vicinity of the Planck length, and the long wavelength limit is the size of the universe itself (see physical cosmology), although in principle the spectrum is infinite and continuous. â€œkmâ€ redirects here. ... For other uses, see Atom (disambiguation). ... The Planck length, denoted by , is the unit of length approximately 1. ... For other uses, see Universe (disambiguation). ... This article is about the physics subject. ... For other uses, see Infinity (disambiguation). ... Continuum theories or models explain variation as involving a gradual quantitative transition without abrupt changes or discontinuities. ...

Legend[2][3][4]
 γ= Gamma rays MIR= Mid infrared HF= High freq. HX= Hard X-Rays FIR= Far infrared MF= Medium freq. SX= Soft X-Rays Radio waves LF= Low freq. EUV= Extreme ultraviolet EHF= Extremely high freq. VLF= Very low freq. NUV= Near ultraviolet SHF= Super high freq. VF/ULF= Voice freq. Visible light UHF= Ultra high freq. SLF= Super low freq. NIR= Near Infrared VHF= Very high freq. ELF= Extremely low freq. Freq=Frequency

## Range of the spectrum GA_googleFillSlot("encyclopedia_square");

The spectrum covers EM wave energy having wavelengths from thousands of meters down to fractions of the size of an atom. Frequencies of 30 Hz and below can be produced by and are important in the study of certain stellar nebulae[5] and frequencies as high as 2.9 * 1027 Hz have been detected from astrophysical sources.[6] For other uses, see Atom (disambiguation). ...

Electromagnetic energy at a particular wavelength λ (in vacuum) has an associated frequency f and photon energy E. Thus, the electromagnetic spectrum may be expressed equally well in terms of any of these three quantities. They are related by the equations: For other uses, see Wavelength (disambiguation). ... Look up Î›, Î» in Wiktionary, the free dictionary. ... For other uses, see Frequency (disambiguation). ... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ...

$c = ,!$frequency x wavelength or $lambda = frac{c}{f} ,!$ and $E=hf ,!$ or $E=frac{hc}{lambda} ,!$

Where $c=299,792,458,!$m/s (speed of light) and $h,!$ is Planck's constant, $(h approx 6.626069 cdot 10^{-34} mbox{J} cdot mbox{s} approx 4.13567 mathrm{mu} mbox{eV}/mbox{GHz})$. The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning swiftness.[1] It is the speed of all electromagnetic radiation, including visible light, in a vacuum. ... A commemoration plaque for Max Planck on his discovery of Plancks constant, in front of Humboldt University, Berlin. ...

So, high-frequency electromagnetic waves have a short wavelength and high energy; low-frequency waves have a long wavelength and low energy.

Whenever light waves (and other electromagnetic waves) exist in a medium (matter), their wavelength is reduced. Wavelengths of electromagnetic radiation, no matter what medium they are traveling through, are usually quoted in terms of the vacuum wavelength, although this is not always explicitly stated. For other uses, see Wavelength (disambiguation). ...

The behavior of EM radiation depends on its wavelength. Higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths. When EM radiation interacts with single atoms and molecules, its behavior also depends on the amount of energy per quantum it carries. Electromagnetic radiation can be divided into octaves — as sound waves are.[7] For other uses, see Octave (disambiguation). ...

Spectroscopy can detect a much wider region of the EM spectrum than the visible range of 400 nm to 700 nm. A common laboratory spectroscope can detect wavelengths from 2 nm to 2500 nm. Detailed information about the physical properties of objects, gases, or even stars can be obtained from this type of device. It is widely used in astrophysics. For example, many hydrogen atoms emit radio waves which have a wavelength of 21.12 cm. Animation of the dispersion of light as it travels through a triangular prism. ... Spiral Galaxy ESO 269-57 Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties (luminosity, density, temperature, and chemical composition) of celestial objects such as stars, galaxies, and the interstellar medium, as well as their interactions. ... This article is about the chemistry of hydrogen. ... For other uses, see Atom (disambiguation). ... In physics, emission is the process by which the energy of a photon is released by another entity, for example, by an atom whose valence electrons make a transition between two electronic energy levels. ... Radio frequency, or RF, refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current fed to an antenna. ... For other uses, see Wavelength (disambiguation). ... A centimetre (American spelling centimeter, symbol cm) is a unit of length that is equal to one hundredth of a metre, the current SI base unit of length. ...

Electromagnetic Spectrum Image.

While the classification scheme is generally accurate, in reality there is often some overlap between neighboring types of electromagnetic energy. For example, SLF radio waves at 60 Hz may be received and studied by astronomers, or may be ducted along wires as electric power. Also, some low-energy gamma rays actually have a longer wavelength than some high-energy X-rays. This is possible because "gamma ray" is the name given to the photons generated from nuclear decay or other nuclear and subnuclear processes, whereas X-rays on the other hand are generated by electronic transitions involving highly energetic inner electrons. Therefore the distinction between gamma ray and X-ray is related to the radiation source rather than the radiation wavelength.[citation needed] Generally, nuclear transitions are much more energetic than electronic transitions, so usually, gamma-rays are more energetic than X-rays. However, there are a few low-energy nuclear transitions (e.g. the 14.4 keV nuclear transition of Fe-57) that produce gamma rays that are less energetic than some of the higher energy X-rays. Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. ... For other uses, see Electron (disambiguation). ... General Name, symbol, number iron, Fe, 26 Chemical series transition metals Group, period, block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ...

Radio waves can be made to carry information by varying a combination of the amplitude, frequency and phase of the wave within a frequency band and the use of the radio spectrum is regulated by many governments through frequency allocation. When EM radiation impinges upon a conductor, it couples to the conductor, travels along it, and induces an electric current on the surface of that conductor by exciting the electrons of the conducting material. This effect (the skin effect) is used in antennas. EM radiation may also cause certain molecules to absorb energy and thus to heat up; this is exploited in microwave ovens. The electromagnetic spectrum is an aspect of the physical world, like land, water, and air. ... In science and engineering, conductors, such as copper or aluminum, are materials with atoms having loosely held valence electrons. ... Radio frequency induction or RF induction is an electrical phenomenon in which an electromagnetic wave passing through a conductor causes electric current to flow through it. ... The skin effect is the tendency of an alternating electric current (AC) to distribute itself within a conductor so that the current density near the surface of the conductor is greater than that at its core. ... Microwave oven A microwave oven, or microwave, is a kitchen appliance employing microwave radiation primarily to cook or heat food. ...

### Microwaves

Main article: Microwaves
Plot of Earth's atmospheric transmittance (or opacity) to various wavelengths of electromagnetic radiation.

The average microwave oven, when active, is at close range, powerful enough to cause interference with poorly shielded electromagnetic fields such as those found in mobile medical devices and cheap consumer electronics.

Terahertz radiation is a region of the spectrum between far infrared and microwaves. Until recently, the range was rarely studied and few sources existed for microwave energy at the high end of the band (sub-millimetre waves or so-called terahertz waves), but applications such as imaging and communications are now appearing. Scientists are also looking to apply Terahertz technology in the armed forces, where high frequency waves might be directed at enemy troops to incapacitate their electronic equipment. Electromagnetic waves sent at terahertz frequencies, known as terahertz radiation, terahertz waves, terahertz light, T-rays, T-light, T-lux and THz, are in the region of the electromagnetic spectrum between 300 gigahertz (3x1011 Hz) and 3 terahertz (3x1012 Hz), corresponding to the wavelength range starting at submillimeter (<1 millimeter... Electromagnetic waves sent at terahertz frequencies, known as terahertz radiation, terahertz waves, terahertz light, T-rays, T-light, T-lux and THz, are in the region of the electromagnetic spectrum between 300 gigahertz (3x1011 Hz) and 3 terahertz (3x1012 Hz), corresponding to the wavelength range starting at submillimeter (<1 millimeter...

The infrared part of the electromagnetic spectrum covers the range from roughly 300 GHz (1 mm) to 400 THz (750 nm). It can be divided into three parts: Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... For other uses, see Infrared (disambiguation). ...

• Far-infrared, from 300 GHz (1 mm) to 30 THz (10 μm). The lower part of this range may also be called microwaves. This radiation is typically absorbed by so-called rotational modes in gas-phase molecules, by molecular motions in liquids, and by phonons in solids. The water in the Earth's atmosphere absorbs so strongly in this range that it renders the atmosphere effectively opaque. However, there are certain wavelength ranges ("windows") within the opaque range which allow partial transmission, and can be used for astronomy. The wavelength range from approximately 200 μm up to a few mm is often referred to as "sub-millimetre" in astronomy, reserving far infrared for wavelengths below 200 μm.
• Mid-infrared, from 30 to 120 THz (10 to 2.5 μm). Hot objects (black-body radiators) can radiate strongly in this range. It is absorbed by molecular vibrations, that is, when the different atoms in a molecule vibrate around their equilibrium positions. This range is sometimes called the fingerprint region since the mid-infrared absorption spectrum of a compound is very specific for that compound.
• Near-infrared, from 120 to 400 THz (2,500 to 750 nm). Physical processes that are relevant for this range are similar to those for visible light.

A phonon is a quantized mode of vibration occurring in a rigid crystal lattice, such as the atomic lattice of a solid. ... Submillimetre Astronomy is the branch of observational astronomy that is conducted at submillimetre wavelengths. ... As the temperature decreases, the peak of the black-body radiation curve moves to lower intensities and longer wavelengths. ...

Main article: Visible spectrum
Visible Electromagnetic spectrum illustration.

Above infrared in frequency comes visible light. This is the range in which the sun and stars similar to it emit most of their radiation. It is probably not a coincidence that the human eye is sensitive to the wavelengths that the sun emits most strongly. Visible light (and near-infrared light) is typically absorbed and emitted by electrons in molecules and atoms that move from one energy level to another. The light we see with our eyes is really a very small portion of the electromagnetic spectrum. A rainbow shows the optical (visible) part of the electromagnetic spectrum; infrared (if you could see it) would be located just beyond the red side of the rainbow with ultraviolet appearing just beyond the violet end. Visible light redirects here. ... Image File history File links Spectre. ... Image File history File links Spectre. ... The optical spectrum (light or visible spectrum) is the portion of the electromagnetic spectrum that is visible to the human eye. ... Sol redirects here. ... This article is about the astronomical object. ... The luminosity function is a standard function established by the Commission Internationale de lÉclairage to account for the variable sensitivity of the human eye to radiation at different wavelengths. ... For other uses, see Rainbow (disambiguation). ... For other uses, see Ultraviolet (disambiguation). ...

EM radiation with a wavelength between approximately 400 nm and 700 nm is detected by the human eye and perceived as visible light. Other wavelengths, especially nearby infrared (longer than 700 nm) and ultraviolet (shorter than 400 nm) are also sometimes referred to as light, especially when the visibility to humans is not relevant. For other uses, see Wavelength (disambiguation). ... A nanometre (American spelling: nanometer, symbol nm) (Greek: Î½Î¬Î½Î¿Ï‚, nanos, dwarf; Î¼ÎµÏ„ÏÏŽ, metrÏŒ, count) is a unit of length in the metric system, equal to one billionth of a metre (or one millionth of a millimetre), which is the current SI base unit of length. ...

If radiation having a frequency in the visible region of the EM spectrum reflects off of an object, say, a bowl of fruit, and then strikes our eyes, this results in our visual perception of the scene. Our brain's visual system processes the multitude of reflected frequencies into different shades and hues, and through this not-entirely-understood psychophysical phenomenon, most people perceive a bowl of fruit. In psychology, visual perception is the ability to interpret visible light information reaching the eyes which is then made available for planning and action. ...

At most wavelengths, however, the information carried by electromagnetic radiation is not directly detected by human senses. Natural sources produce EM radiation across the spectrum, and our technology can also manipulate a broad range of wavelengths. Optical fiber transmits light which, although not suitable for direct viewing, can carry data that can be translated into sound or an image. The coding used in such data is similar to that used with radio waves. Optical fibers An optical fiber (or fibre) is a glass or plastic fiber designed to guide light along its length. ...

### Ultraviolet light

Main article: Ultraviolet
The amount of penetration of UV relative to altitude in Earth's ozone

Next in frequency comes ultraviolet (UV). This is radiation whose wavelength is shorter than the violet end of the visible spectrum. For other uses, see Ultraviolet (disambiguation). ... Levels of ozone at various altitudes, and related blocking of several types of ultraviolet radiation. ... Levels of ozone at various altitudes, and related blocking of several types of ultraviolet radiation. ... The ozone layer is a layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). ... For other uses, see Ultraviolet (disambiguation). ... Visible light redirects here. ...

Being very energetic, UV can break chemical bonds, making molecules unusually reactive or ionizing them, in general changing their mutual behavior. Sunburn, for example, is caused by the disruptive effects of UV radiation on skin cells, which can even cause skin cancer, if the radiation damages the complex DNA molecules in the cells (UV radiation is a proven mutagen). The Sun emits a large amount of UV radiation, which could quickly turn Earth into a barren desert; however, most of it is absorbed by the atmosphere's ozone layer before reaching the surface. For other uses, see Skin (disambiguation). ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... Skin cancer is a malignant growth on the skin which can have many causes. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... In biology, a mutagen (Latin, literally origin of change) is a physical or chemical agent that changes the genetic information (usually DNA) of an organism and thus increases the number of mutations above the natural background level. ... The ozone layer is a layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). ...

### X-rays

Main article: X-rays

After UV come X-rays. Hard X-rays have shorter wavelengths than soft X-rays. X-rays are used for seeing through some things and not others, as well as for high-energy physics and astronomy. Neutron stars and accretion disks around black holes emit X-rays, which enable us to study them. An X-ray picture (radiograph), taken by Wilhelm RÃ¶ntgen in 1896, of his wife, Anna Bertha Ludwigs[1] hand X-rays (or RÃ¶ntgen rays) are a form of electromagnetic radiation with a wavelength in the range of 10 to 0. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... For the story by Larry Niven, see Neutron Star (story). ... For other uses, see Black hole (disambiguation). ...

X-rays will pass through most substances, and this makes them useful in medicine and industry. X-rays are given off by stars, and strongly by some types of nebulae. An X-ray machine works by firing a beam of electrons at a "target". If the electrons were fired with enough energy, X-rays will be produced. Mrs. ...

### Gamma rays

Main article: Gamma rays

Note that there are no precisely defined boundaries between the bands of the electromagnetic spectrum. Radiation of some types have a mixture of the properties of those in two regions of the spectrum. For example, red light resembles infra-red radiation in that it can resonate some chemical bonds. This article is about resonance in physics. ... In chemistry, a chemical bond is the force which holds together atoms in molecules or crystals. ...

 Electronics Portal

Image File history File links Zenerdiod_symbol. ... The atmospheric window refers to those parts of the electromagnetic spectrum that are, with the earths atmosphere in its natural state, not absorbed at all. ... The ozone layer is a layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). ... A bandplan or band plan is a plan for utilizing a particular band of radio frequencies, that are a portion of the Electromagnetic spectrum . ... Electromagnetic spectroscopy a. ... Radiant energy is the energy of electromagnetic waves. ... Animation of the dispersion of light as it travels through a triangular prism. ... The V band (vee-band) of the electromagnetic spectrum ranges from 50 to 75 GHz. ... The W band of the microwave part of the electromagnetic spectrum and ranges from 75 to 111 GHz. ...

## References

1. ^ {{cite web|url=http://imagine.gsfc.nasa.gov/docs/dict_ei.html#em_spectrum|title=Imagine the Universe! Dictionary
2. ^ What is Light? – UC Davis lecture slides
3. ^ The Electromagnetic Spectrum, The Physics Hypertextbook
4. ^ Definition of frequency bands on vlf.it
5. ^ J. J. Condon and S. M. Ransom. Essential Radio Astronomy: Pulsar Properties. National Radio Astronomy Observatory. Retrieved on 2008-01-05.
6. ^ "Discovery of TeV Gamma‐Ray Emission from the Cygnus Region of the Galaxy" (2007 March 20). The Astrophysical Journal Letters. Retrieved on 2008-01-05.
7. ^ Isaac Asimov, Isaac Asimov's Book of Facts. Hastingshouse/Daytrips Publ., 1992. Page 389.

The University of California, Davis, commonly abbreviated to UC Davis or UCD is one of the ten University of California campuses. ... The National Radio Astronomy Observatory (NRAO) is an institution set up by the United States government for the purpose of radio astronomy. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... is the 5th day of the year in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... is the 5th day of the year in the Gregorian calendar. ...

Results from FactBites:

 Electromagnetic spectrum - Wikipedia, the free encyclopedia (1438 words) The electromagnetic spectrum is the range of all possible electromagnetic radiation. The electromagnetic spectrum, shown in the table, extends from frequencies used in the electric power grid (at the long-wavelength end) to gamma radiation (at the short-wavelength end), covering wavelengths from thousands of kilometres down to fractions of the size of an atom. Electromagnetic spectroscopy is the branch of physics that deals with the characterization of matter by its spectra.
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