FACTOID # 17: Though Rhode Island is the smallest state in total area, it has the longest official name: The State of Rhode Island and Providence Plantations.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
RELATED ARTICLES
People who viewed "Black body" also viewed:
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Black body
As the temperature decreases, the peak of the black-body radiation curve moves to lower intensities and longer wavelengths. The black-body radiation graph is also compared with the classical model of Rayleigh and Jeans.
As the temperature decreases, the peak of the black-body radiation curve moves to lower intensities and longer wavelengths. The black-body radiation graph is also compared with the classical model of Rayleigh and Jeans.
The color (chromaticity) of black-body radiation depends on the temperature of the black body; the locus of such colors, shown here in CIE 1931 x,y space, is known as the Planckian locus.
The color (chromaticity) of black-body radiation depends on the temperature of the black body; the locus of such colors, shown here in CIE 1931 x,y space, is known as the Planckian locus.

In physics, a black body is an object that absorbs all electromagnetic radiation that falls onto it. No radiation passes through it and none is reflected. It is this lack of both transmission and reflection to which the name refers. These properties make black bodies ideal sources of thermal radiation. That is, the amount and spectrum of electromagnetic radiation they emit is directly related to their temperature. Black bodies below around 700 K (430 °C) produce very little radiation at visible wavelengths and appear black. Black bodies above this temperature however, produce radiation at visible wavelengths starting at red, going through orange, yellow, and white before ending up at blue as the temperature increases. Image File history File links Size of this preview: 800 × 541 pixelsFull resolution (2025 × 1370 pixel, file size: 35 KB, MIME type: image/png) Blackbody curves for various temperatures and comparison with classical theory. ... Image File history File links Size of this preview: 800 × 541 pixelsFull resolution (2025 × 1370 pixel, file size: 35 KB, MIME type: image/png) Blackbody curves for various temperatures and comparison with classical theory. ... Download high resolution version (1300x1462, 524 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (1300x1462, 524 KB) Wikipedia does not have an article with this exact name. ... Chromaticity is the quality of a color as determined by its purity and dominant wavelength. ... In the study of the perception of color, one of the first mathematically defined color spaces was the CIE XYZ color space (also known as CIE 1931 color space), created by the International Commission on Illumination (CIE) in 1931. ... In Color theory, the Planckian locus is generally the path that the color of a black body would take in a particular color space as the blackbody temperature changes. ... A magnet levitating above a high-temperature superconductor demonstrates the Meissner effect. ... A physical body is an object which can be described by the theories of classical mechanics, or quantum mechanics, and experimented upon by physical instruments. ... Electromagnetic waves can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. ... The reflection of a bridge in Indianapolis, Indianas Central Canal. ... Radiant heat redirects here. ... Legend γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High... For other uses, see Kelvin (disambiguation). ...


The term "black body" was introduced by Gustav Kirchhoff in 1860. The light emitted by a black body is called black-body radiation (or cavity radiation), and has a special place in the history of quantum mechanics.[1] Gustav Robert Kirchhof (March 12, 1824 – October 17, 1887) was a German physicist who contributed to the fundamental understanding of electrical circuits, spectroscopy, and the emission of black-body radiation by heated objects. ... 1860 is the leap year starting on Sunday. ... As the temperature decreases, the peak of the black body radiation curve moves to lower intensities and longer wavelengths. ... Niels Bohr’s 1913 quantum model of the atom, which incorporated an explanation of Johannes Rydbergs 1888 formula, Max Planck’s 1900 quantum hypothesis, i. ...

Contents

Explanation

In the laboratory, a black-body radiation is approximated by the radiation from a small hole entrance to a large cavity, a hohlraum. Any light entering the hole would have to reflect off the walls of the cavity multiple times before it escaped, in which process it is nearly certain to be absorbed. This occurs regardless of the wavelength of the radiation entering (as long as it is small compared to the hole). The hole, then, is a close approximation of a theoretical black body and, if the cavity is heated, the spectrum of the hole's radiation (i.e., the amount of light emitted from the hole at each wavelength) will be continuous, and will not depend on the material in the cavity (compare with emission spectrum). By a theorem proved by Kirchhoff, this curve depends only on the temperature of the cavity walls.[2] Image File history File links This is a lossless scalable vector image. ... In radiation thermodynamics, a hohlraum (in literal German, a hollow area or cavity, a term of art synonymous with radiation case) is a cavity whose walls are in radiative equilibrium with the radiant energy within the cavity. ... For other uses, see Wavelength (disambiguation). ... In physics, the spectral density, or more correctly the power spectral density (PSD) of a given bandwidth of electromagnetic radiation is the total power in this bandwidth divided by the specified bandwidth. ... For other uses, see Wavelength (disambiguation). ... An elements emission spectrum is the relative intensity of electromagnetic radiation of each frequency it emits when it is heated (or more generally when it is excited). ... Kirchhoffs law in thermodynamics, also called e. ... For other uses, see Temperature (disambiguation). ...


Calculating this curve was a major challenge in theoretical physics during the late nineteenth century. The problem was finally solved in 1901 by Max Planck as Planck's law of black-body radiation.[3] By making changes to Wien's Radiation Law (not to be confused with Wien's displacement law) consistent with Thermodynamics and Electromagnetism, he found a mathematical formula fitting the experimental data in a satisfactory way. To find a physical interpretation for this formula, Planck had then to assume that the energy of the oscillators in the cavity was quantized (i.e., integer multiples of some quantity). Einstein built on this idea and proposed the quantization of electromagnetic radiation itself in 1905 to explain the photoelectric effect. These theoretical advances eventually resulted in the superseding of classical electromagnetism by quantum electrodynamics. Today, these quanta are called photons and the black-body cavity may be thought of as containing a gas of photons. In addition, it led to the development of quantum versions of statistical mechanics, called Fermi-Dirac statistics and Bose-Einstein statistics, each applicable to a different class of particles. See also fermion and boson. “Planck” redirects here. ... In physics, the spectral intensity of electromagnetic radiation from a black body at temperature T is given by the Plancks law of black body radiation: where: I(ν) is the amount of energy per unit time per unit surface area per unit solid angle per unit frequency. ... Wiens Radiation Law (not to be mistaken with Wiens Displacement Law) was a law of physics that was built to explain the black body radiation spectrum. ... Wiens displacement law is a law of physics that states that there is an inverse relationship between the wavelength of the peak of the emission of a black body and its temperature. ... Thermodynamics (from the Greek θερμη, therme, meaning heat and δυναμις, dynamis, meaning power) is a branch of physics that studies the effects of changes in temperature, pressure, and volume on physical systems at the macroscopic scale by analyzing the collective motion of their particles using statistics. ... Electromagnetism is the physics of the electromagnetic field: a field which exerts a force on particles that possess the property of electric charge, and is in turn affected by the presence and motion of those particles. ... “Einstein” redirects here. ... A diagram illustrating the emission of electrons from a metal plate, requiring energy gained from an incoming photon to be more than the work function of the material. ... Quantum electrodynamics (QED) is a relativistic quantum field theory of electrodynamics. ... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ... In physics, a photon gas is a gas-like collection of photons, which come together to form something that has the properties of a conventional gas like hydrogen or neon - including pressure, and temperature. ... Fermi-Dirac distribution as a function of ε/μ plotted for 4 different temperatures. ... In statistical mechanics, Bose-Einstein statistics determines the statistical distribution of identical indistinguishable bosons over the energy states in thermal equilibrium. ... In particle physics, fermions are particles with half-integer spin, such as protons and electrons. ... In particle physics, bosons, named after Satyendra Nath Bose, are particles having integer spin. ...

The temperature of a Pahoehoe lava flow can be estimated by observing its color. The result agrees well with the measured temperatures of lava flows at about 1,000 to 1,200 °C.
The temperature of a Pahoehoe lava flow can be estimated by observing its color. The result agrees well with the measured temperatures of lava flows at about 1,000 to 1,200 °C.

The wavelength at which the radiation is strongest is given by Wien's displacement law, and the overall power emitted per unit area is given by the Stefan-Boltzmann law. So, as temperature increases, the glow color changes from red to yellow to white to blue. Even as the peak wavelength moves into the ultra-violet enough radiation continues to be emitted in the blue wavelengths that the body will continue to appear blue. It will never become invisible — indeed, the radiation of visible light increases monotonically with temperature.[4] Advancing Pahoehoe toe, Kilauea Hawaii 2003 Kohola breakouts and Highcastle ocean entry File links The following pages link to this file: Lava Black body Categories: USGS images ... Advancing Pahoehoe toe, Kilauea Hawaii 2003 Kohola breakouts and Highcastle ocean entry File links The following pages link to this file: Lava Black body Categories: USGS images ... Lava is molten rock that a volcano expels during an eruption. ... Wiens displacement law is a law of physics that states that there is an inverse relationship between the wavelength of the peak of the emission of a black body and its temperature. ... The Stefan-Boltzmann law, also known as Stefans law, states that the total energy radiated per unit surface area of a black body in unit time (known variously as the black-body irradiance, energy flux density, radiant flux, or the emissive power), j*, is directly proportional to the fourth... A monotonically increasing function (it is strictly increasing on the left and just non-decreasing on the right). ...


The radiance or observed intensity is not a function of direction. Therefore a black body is a perfect Lambertian radiator. Radiance and spectral radiance are radiometric measures that describe the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle in a specified direction. ... Lamberts cosine law says that the total radiant power observed from a Lambertian surface is directly proportional to the cosine of the angle θ between the observers line of sight and the surface normal. ...


Real objects never behave as full-ideal black bodies, and instead the emitted radiation at a given frequency is a fraction of what the ideal emission would be. The emissivity of a material specifies how well a real body radiates energy as compared with a black body. This emissivity depends on factors such as temperature, emission angle, and wavelength. However, it is typical in engineering to assume that a surface's spectral emissivity and absorptivity do not depend on wavelength, so that the emissivity is a constant. This is known as the grey body assumption. The emissivity of a material (usually written ) is the ratio of energy radiated by the material to energy radiated by a black body at the same temperature. ...


Although Planck's formula predicts that a black body will radiate energy at all frequencies, the formula is only applicable when many photons are being measured. For example, a black body at room temperature (300 K) with one square meter of surface area will emit a photon in the visible range once every thousand years or so, meaning that for most practical purposes, the black body does not emit in the visible range.


When dealing with non-black surfaces, the deviations from ideal black-body behavior are determined by both the geometrical structure and the chemical composition, and follow Kirchhoff's Law: emissivity equals absorptivity, so that an object that does not absorb all incident light will also emit less radiation than an ideal black body. Kirchhoffs law in thermodynamics, also called e. ...

WMAP image of the cosmic microwave background radiation anisotropy. It has the most perfect thermal emission spectrum known and corresponds to a temperature of 2.725 kelvin (K) with an emission peak at 160.2 GHz.
WMAP image of the cosmic microwave background radiation anisotropy. It has the most perfect thermal emission spectrum known and corresponds to a temperature of 2.725 kelvin (K) with an emission peak at 160.2 GHz.

In astronomy, objects such as stars are frequently regarded as black bodies, though this is often a poor approximation. An almost perfect black-body spectrum is exhibited by the cosmic microwave background radiation. Hawking radiation is black-body radiation emitted by black holes. Image File history File links Download high resolution version (2198x1274, 1278 KB)WMAP map of CMB anisotropy, from NASA.gov 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 Download high resolution version (2198x1274, 1278 KB)WMAP map of CMB anisotropy, from NASA.gov File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Artist depiction of the WMAP satellite at the L2 point The Wilkinson Microwave Anisotropy Probe (WMAP) is a NASA satellite whose mission is to survey the sky to measure the temperature of the radiant heat left over from the Big Bang. ... WMAP image of the CMB anisotropy,Cosmic microwave background radiation(June 2003) The cosmic microwave background radiation (CMB) is a form of electromagnetic radiation that fills the whole of the universe. ... Look up anisotropy in Wiktionary, the free dictionary. ... Radiant heat redirects here. ... For other uses, see Kelvin (disambiguation). ... A gigahertz is a billion hertz or a thousand megahertz, a measure of frequency. ... For other uses, see Astronomy (disambiguation). ... This article is about the astronomical object. ... CMB redirects here. ... In physics, Hawking radiation (also known as Bekenstein-Hawking radiation) is a thermal radiation thought to be emitted by black holes due to quantum effects. ... For other uses, see Black hole (disambiguation). ...


Equations governing black bodies

Planck's law of black-body radiation

I(nu) = frac{2 hnu^{3}}{c^2}frac{1}{e^{frac{hnu}{kT}}-1}

where In physics, the spectral intensity of electromagnetic radiation from a black body at temperature T is given by the Plancks law of black body radiation: where: I(ν) is the amount of energy per unit time per unit surface area per unit solid angle per unit frequency. ...

Area is the measure of how much exposed area any two dimensional object has. ... Look up time in Wiktionary, the free dictionary. ... A solid angle is the three dimensional analog of the ordinary angle. ... For other uses, see Temperature (disambiguation). ... A commemoration plaque for Max Planck on his discovery of Plancks constant, in front of Humboldt University, Berlin. ... 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. ... The Boltzmann constant (k or kB) is the physical constant relating temperature to energy. ...

Wien's displacement law

The relationship between the temperature T of a black body, and wavelength λmax at which the intensity of the radiation it produces is at a maximum is Wiens displacement law is a law of physics that states that there is an inverse relationship between the wavelength of the peak of the emission of a black body and its temperature. ...

T lambda_mathrm{max} = 2.898... times 10^6  mathrm{nm  K}. ,

The nanometer is a convenient unit of measure for optical wavelengths. Note that 1 nanometer is equivalent to 10−9 meters. A nanometre (American spelling: nanometer) is 1. ... For the book by Sir Isaac Newton, see Opticks. ... This article is about the unit of length. ...


Stefan–Boltzmann law

Main article: Stefan–Boltzmann law

The total energy radiated per unit area per unit time j^{star} (in watts per square meter) by a black body is related to its temperature T (in kelvins) and the Stefan-Boltzmann constant σ as follows: The Stefan-Boltzmann law, also known as Stefans law, states that the total energy radiated per unit surface area of a black body in unit time (known variously as the black-body irradiance, energy flux density, radiant flux, or the emissive power), j*, is directly proportional to the fourth... For other uses, see Watt (disambiguation). ... A square metre (US spelling: square meter) is by definition the area enclosed by a square with sides each 1 metre long. ... For other uses, see Kelvin (disambiguation). ... The Stefan-Boltzmann constant (also Stefans constant), denoted with a Greek letter σ, is a derivable physical constant, the constant of proportionality between the total energy radiated per unit surface area of a black body in unit time and the fourth power of the thermodynamic temperature, as per the...

j^{star} = sigma T^4.,

Radiation emitted by a human body

Much of a person's energy is radiated away in the form of infrared energy. Some materials are transparent to infrared light, while opaque to visible light (note the plastic bag). Other materials are transparent to visible light, while opaque to the infrared (note the man's eyeglasses).

Black-body laws can be applied to human beings. For example, some of a person's energy is radiated away in the form of electromagnetic radiation, most of which is infrared. Image File history File links Human-Visible. ... Image File history File links Human-Infrared. ... For other uses, see Infrared (disambiguation). ... For other uses, see Infrared (disambiguation). ...


The net power radiated is the difference between the power emitted and the power absorbed:

Pnet = PemitPabsorb.

Applying the Stefan-Boltzmann law,

P_{net}=Asigma epsilon left( T^4 - T_{0}^4 right) ,.

The total surface area of an adult is about 2 m², and the mid- and far-infrared emissivity of skin and most clothing is near unity, as it is for most nonmetallic surfaces.[5][6] Skin temperature is about 33°C,[7] but clothing reduces the surface temperature to about 28°C when the ambient temperature is 20°C.[8] Hence, the net radiative heat loss is about The emissivity of a material (usually written ) is the ratio of energy radiated by the material to energy radiated by a black body at the same temperature. ...

P_{net} = 100  mathrm{W} ,.

The total energy radiated in one day is about 9 MJ (million joules), or 2000 kcal (food calories). Basal metabolic rate for a 40-year-old male is about 35 kcal/(m²·h),[9] which is equivalent to 1700 kcal per day assuming the same 2 m² area. However, the mean metabolic rate of sedentary adults is about 50% to 70% greater than their basal rate.[10] The joule (IPA: or ) (symbol: J) is the SI unit of energy. ... Etymology: French calorie, from Latin calor (heat), from calere (to be warm). ... Basal metabolic rate (BMR) is the amount of energy expended while at rest in a neutrally temperate environment, in the post-absorptive state (meaning that the digestive system is inactive, which requires about twelve hours of fasting in humans). ...


There are other important thermal loss mechanisms, including convection and evaporation. Conduction is negligible since the Nusselt number is much greater than unity. Evaporation (perspiration) is only required if radiation and convection are insufficient to maintain a steady state temperature. Free convection rates are comparable, albeit somewhat lower, than radiative rates.[11] Thus, radiation accounts for about 2/3 of thermal energy loss in cool, still air. Given the approximate nature of many of the assumptions, this can only be taken as a crude estimate. Ambient air motion, causing forced convection, or evaporation reduces the relative importance of radiation as a thermal loss mechanism. Convection in the most general terms refers to the movement of currents within fluids (i. ... “Vaporization” redirects here. ... The Nusselt number is a dimensionless number which measures the enhancement of heat transfer from a surface which occurs in a real situation, compared to the heat transfer that would be measured if only conduction could occur. ... Perspiration (also called sweating or sometimes transpiration) is the production and evaporation of a fluid, consisting primarily of water as well as a smaller amount of sodium chloride (the main constituent of table salt), that is excreted by the sweat glands in the skin of mammals. ...


Also, applying Wien's Law to humans, one finds that the peak wavelength of light emitted by a person is Wiens displacement law is a law of physics that states that there is an inverse relationship between the wavelength of the peak of the emission of a black body and its temperature. ...

lambda_{peak} = frac{2.898times 10^6  mathrm{K} cdot mathrm{nm}}{305  mathrm{K}} = 9500  mathrm{nm} ,.

This is why thermal imaging devices designed for human subjects are most sensitive to 7–14 micrometers wavelength.


Temperature relation between a planet and its star

Here is an application of black-body laws. It is a rough derivation that gives an order of magnitude answer. See p. 380-382 of Planetary Science, for further discussion.[12]


Factors

Earth's longwave thermal radiation intensity, from clouds, atmosphere and ground
Earth's longwave thermal radiation intensity, from clouds, atmosphere and ground

The surface temperature of a planet depends on a few factors: Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... The Earth can be considered as a physical system with an energy budget that includes all gains of incoming energy and all losses of outgoing energy. ...

  • Incident radiation (from the Sun, for example)
  • Emitted radiation (for example Earth's infrared glow)
  • The albedo effect (the fraction of light a planet reflects)
  • The greenhouse effect (for planets with an atmosphere)
  • Energy generated internally by a planet itself (This is more important for planets like Jupiter)

For the inner planets, incident and emitted radiation have the most significant impact on surface temperature. This derivation is concerned mainly with that. The Earth can be considered as a physical system with an energy budget that includes all gains of incoming energy and all losses of outgoing energy. ... For other uses, see Albedo (disambiguation). ... Wikinews has related news: Scientists warn thawing Siberia may trigger global meltdown A schematic representation of the exchanges of energy between outer space, the Earths atmosphere, and the Earth surface. ...


Assumptions

If we assume the following:

  1. The Sun and the Earth both radiate as spherical black bodies in thermal equilibrium with themselves.
  2. The Earth absorbs all the solar energy that it intercepts from the Sun.

then we can derive a formula for the relationship between the Earth's surface temperature and the Sun's surface temperature. In thermodynamics, a thermodynamic system is in thermodynamic equilibrium if its energy distribution equals a Maxwell-Boltzmann-distribution. ...


Derivation

To begin, we use the Stefan-Boltzmann law to find the total power (energy/second) the Sun is emitting: The Stefan-Boltzmann law, also known as Stefans law, states that the total energy radiated per unit surface area of a black body in unit time (known variously as the black-body irradiance, energy flux density, radiant flux, or the emissive power), j*, is directly proportional to the fourth... In physics, power (symbol: P) is the rate at which work is performed or energy is transmitted, or the amount of energy required or expended for a given unit of time. ...

The Earth only has an absorbing area equal to a two dimensional circle, rather than the surface of a sphere.
The Earth only has an absorbing area equal to a two dimensional circle, rather than the surface of a sphere.
P_{S emt} = left( sigma T_{S}^4 right) left( 4 pi R_{S}^2 right) qquad qquad (1)
where
sigma , is the Stefan-boltzmann constant,
T_S , is the surface temperature of the Sun, and
R_S , is the radius of the Sun.

The Sun emits that power equally in all directions. Because of this, the Earth is hit with only a tiny fraction of it. This is the power from the Sun that the Earth absorbs: Image File history File links Sun-Earth-Radiation. ... The Stefan-Boltzmann law, also known as Stefans law, states that the total energy radiated per unit surface area of a black body in unit time (known variously as the black-body irradiance, energy flux density, radiant flux, or the emissive power), j*, is directly proportional to the fourth...

P_{E abs} = P_{S emt} left( frac{pi R_{E}^2}{4 pi D^2} right) qquad qquad (2)
where
R_{E} , is the radius of the Earth and
D , is the distance between the Sun and the Earth.

Even though the earth only absorbs as a circular area πR2, it emits equally in all directions as a sphere:

P_{E emt} = left( sigma T_{E}^4 right) left( 4 pi R_{E}^2 right) qquad qquad (3)
where TE is the surface temperature of the earth.

Now, in the first assumption the earth is in thermal equilibrium, so the power absorbed must equal the power emitted:

P_{E abs} = P_{E emt},
So plug in equations 1, 2, and 3 into this and we get
left( sigma T_{S}^4 right) left( 4 pi R_{S}^2 right) left( frac{pi R_{E}^2}{4 pi D^2} right) = left( sigma T_{E}^4 right) left( 4 pi R_{E}^2 right).,

Many factors cancel from both sides and this equation can be greatly simplified.


The result

After canceling of factors, the final result is

T_{S}sqrt{frac{R_{S}}{2 D}} = T_{E}
where
T_S , is the surface temperature of the Sun,
R_S , is the radius of the Sun,
D , is the distance between the Sun and the Earth, and
T_E , is the average surface temperature of the Earth.

In other words, the temperature of the Earth depends only on the surface temperature of the Sun, the radius of the Sun, and the distance between the Earth and the Sun. The average surface temperature of the earth is defined as the combined temperature of near-surface air temperature over land and sea surface temperature. ...


Temperature of the Sun

If we substitute in the measured values for Earth,

T_{E} approx 14  mathrm{{}^circ C} = 287  mathrm{K},
R_{S} = 6.96 times 10^8  mathrm{m},
D = 1.5 times 10^{11}  mathrm{m},

we'll find the effective temperature of the Sun to be The effective temperature of a star is the temperature of a black body with the same luminosity (L) as the star and is defined according to the Stefan-Boltzman law L = sigma T_{eff}^{4}. The effective temperature of our Sun is around 5,800 kelvins (K) and correspond to...

T_{S} approx 5960  mathrm{K}.

This is within three percent of the standard measure of 5778 kelvins which makes the formula valid for most scientific and engineering applications.


See also

The effective temperature of a star is the temperature of a black body with the same luminosity (L) as the star and is defined according to the Stefan-Boltzman law L = sigma T_{eff}^{4}. The effective temperature of our Sun is around 5,800 kelvins (K) and correspond to... The CIE 1931 x,y chromaticity space, also showing the chromaticities of black-body light sources of various temperatures, and lines of constant correlated color temperature Color temperature is a characteristic of visible light that has important applications in photography, videography, publishing and other fields. ... Infrared thermometers offer a great method for accurately and quickly measuring temperature of objects at a distance and/or in motion. ... Photon polarization is the quantum mechanical description of the classical polarized sinusoidal plane electromagnetic wave. ... The ultraviolet catastrophe, also called the Rayleigh-Jeans catastrophe, was a prediction of early 20th century classical physics that an ideal black body at thermal equilibrium will emit radiation with infinite power. ...

References

  1. ^ When used as a compound adjective, the term is typically hyphenated, as in "black-body radiation", or combined into one word, as in "blackbody radiation". The hyphenated and one-word forms should not generally be used as nouns.
  2. ^ Huang, Kerson (1967). Statistical Mechanics. New York: John Wiley & Sons. 
  3. ^ Planck, Max (1901). "On the Law of Distribution of Energy in the Normal Spectrum" (HTML). Annalen der Physik 4: 553. 
  4. ^ Landau, L. D.; E. M. Lifshitz (1996). Statistical Physics, 3rd Edition Part 1, Oxford: Butterworth-Heinemann. 
  5. ^ Infrared Services. Emissivity Values for Common Materials. Retrieved on 2007-06-24.
  6. ^ Omega Engineering. Emissivity of Common Materials. Retrieved on 2007-06-24.
  7. ^ Elert, G. (ed.). Temperature of a Healthy Human. Retrieved on 2007-06-24.
  8. ^ Lee, B.. Theoretical Prediction and Measurement of the Fabric Surface Apparent Temperature in a Simulated Man/Fabric/Environment System. Retrieved on 2007-06-24.
  9. ^ Harris J, Benedict F (1918). "A Biometric Study of Human Basal Metabolism.". Proc Natl Acad Sci U S A 4 (12): 370-3. PMID 16576330. 
  10. ^ Levine, J (2004). "Nonexercise activity thermogenesis (NEAT): environment and biology". Am J Physiol Endocrinol Metab 286: E675-E685. 
  11. ^ DrPhysics.com. Heat Transfer and the Human Body. Retrieved on 2007-06-24.
  12. ^ Cole, George H. A.; Woolfson, Michael M. (2002). Planetary Science: The Science of Planets Around Stars (1st ed.). Institute of Physics Publishing. ISBN 0-7503-0815-X. 

A compound is a word composed of more than one free morphemes. ... “Planck” redirects here. ... Annalen der Physik is one of the best-known and oldest (it was founded in 1799) physics journals worldwide. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 175th day of the year (176th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 175th day of the year (176th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 175th day of the year (176th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 175th day of the year (176th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 175th day of the year (176th in leap years) in the Gregorian calendar. ...

Other textbooks

  • Kroemer, Herbert; Kittel, Charles (1980). Thermal Physics (2nd ed.). W. H. Freeman Company. ISBN 0-7167-1088-9. 
  • Tipler, Paul; Llewellyn, Ralph (2002). Modern Physics (4th ed.). W. H. Freeman. ISBN 0-7167-4345-0. 

External links


  Results from FactBites:
 
Black body - Wikipedia, the free encyclopedia (1866 words)
As the temperature decreases, the peak of the fl body radiation curve moves to lower intensities and longer wavelengths.
In physics, a fl body is an object that absorbs all electromagnetic radiation that falls onto it.
The hole then is a close approximation of a theoretical fl body and if the cavity is heated, the spectrum of the hole's radiation (i.e., the amount of light emitted from the hole at each wavelength) will be continuous, and will not depend on the material in the cavity (compare with emission spectrum).
Planck's law of black body radiation - Wikipedia, the free encyclopedia (1024 words)
In physics, the spectral intensity of electromagnetic radiation from a fl body at temperature T is given by Planck's law of fl body radiation:
At the time, Planck believed that the quantization applied only to the tiny oscillators that were thought to exist in the walls of the cavity (what we now know to be atoms), and made no assumption that light itself propagates in discrete bundles or packets of energy.
Contrary to another myth, Planck did not derive his law in an attempt to resolve the "ultraviolet catastrophe", the name given to the paradoxical result that the total energy in the cavity tends to infinity when the equipartition theorem of classical statistical mechanics is applied to fl body radiation.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m