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Topic: Blackbody


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 Infrared Blackbody Theory   (Site not responding. Last check: 2007-11-01)
A flbody absorbs all the radiation it receives and radiates more thermal radiation for all wavelength intervals than any other mass of the same area and temperature.
Though the flbody is an ideal, and no perfect flbody exists, specially constructed laboratory sources emit radiation with an efficiency compared to a flbody of 98% or higher.
The most common approach to realizing a flbody is to use a spherical cavity with a small hole in the surface or a closed-end tube that is longer than its diameter.
www.mikroninst.com /products/blackbody/about-blackbody.html   (774 words)

  
 Emissivity
Emissivity is the ratio of radiation emitted by a flbody or a surface and the theoretical radiation predicted by Planck’s law.
Blackbody emissivity is frequently referred to as a single number.
Effective emissivity is affected by several variables, the most important of which are the geometric shape of the flbody, the uniformity of the flbody temperature, the surface emissivity and wavelength dependence.
www.electro-optical.com /bb_rad/emissivity/emisivty.htm   (773 words)

  
 [No title]
Blackbodies do this as well and that is why physicists came up with the name "flbody".
The flbody curve is the particular way the total light emitted by a flbody varies with its frequency.
That is what makes flbodies so useful and that is why the color of a star is also a measure of its temperature.
www.mhhe.com /physsci/astronomy/applets/Blackbody/content_files/whatis.html   (582 words)

  
 NPL: Datasheets: Calibration of Blackbody Sources and Radiation Thermometers
These may be used for the calibration of infrared thermometers and other flbody sources, offering calibration uncertainties of typically 0.1 °C to 1 °C depending on the instrument and temperature range.
Customer flbody sources may be evaluated by comparison with an NPL standard source using either an infrared radiometer or a suite of transfer standard radiation thermometers operating at wavelengths from 0.65 µm to 14 µm.
By immersing a flbody cavity in an ingot of high purity metal, standards may be set up corresponding to one of the ITS-90 fixed points.
www.npl.co.uk /thermal/publications/ds_pm060304.html   (486 words)

  
 BB Radiation
The maximum energy which can be radiated by an object is called the flbody radiation.
Common usage refers to a source of infrared energy as a "flbody" when it's emissivity approaches 1.0 (usually e = 0.99 or better) and as a "graybody" if it has lower emissivity.
flbody radiation given nothing more than the radiative temperature.
www.electro-optical.com /bb_rad/bb_rad.htm   (439 words)

  
 Blackbody Radiation
One such exception was that associated with flbody radiation, which is the characteristic radiation that a body emits when heated.
It was known that this radiation changes in nature as the temperature changes, and experiments on ``flbodies'' (perfect absorbers and emitters) show the following typical curves of the intensity of the radiation (energy emitted per unit time per unit area) vs. the wavelength at a fixed temperature T, as in Fig.
However, it was a radical departure from the conventional picture of light emitted from a flbody, and at the time many people felt it was simply a calculational trick invented to obtain the right answer.
theory.uwinnipeg.ca /physics/quant/node2.html   (301 words)

  
 Blackbody   (Site not responding. Last check: 2007-11-01)
BlackBody Spectrum Applet Shows the relation between wavelength, emitted power, and peak wavelength for a flbody (Planck's function).
Thermo Gauge Instruments Producing precision Blackbody sources for the calibration of optical pyrometers, ir thermometers, thermocouples, fiber optic temperature sensors and heat flux gauges.
Infrared Development Corporation Manufacturer of infrared flbody sources, radiometer systems, calibration services, femtosecond laser pulse acquisition systems, low-noise preamplifiiers for infrared detectors, ir test stations and test sets.
www.serebella.com /encyclopedia/article-Blackbody.html   (160 words)

  
 Appendix A
A flbody is defined as an ideal body that completely absorbs all radiant energy striking it and, therefore, appears perfectly fl at all wavelengths.
A flbody is also a perfect emitter of radiation; one that, for a given temperature, radiates the maximum number of photons possible per unit time per unit area in a specific spectral interval.
The spectral emissivity e(l) of a graybody is defined as the ratio of the spectral photon (or radiant) exitance of the graybody to that of a flbody:
rsd.gsfc.nasa.gov /goes/text/MITRE-GOES_MP93W62/a-a/a-a.html   (633 words)

  
 2000 Series Differential Blackbody. Differential Blackbodies
The Smart Blackbody puts the temperature measurement and calibration electronics, the brains of the system, in the flbody head rather than in the control electronics package.
Blackbody calibration is independent of the controller — replacing the controller does not require recalibration of the flbody.
Temperature measurement information is sent to the flbody controller in the form of a digital stream of data.
www.sbir.com /blackbody_2000.htm   (912 words)

  
 What colour is the Sun?
The flbody colours in the colour chart at top and in the diagram at right were computed by integrating the monochromatic tristimuli X, Y, Z from the CIE 2° tables over a Planck distribution.
Blackbody colours at temperatures around 5000-7000 K are nearly white, and the choice of white point is important if one wants to render these colours accurately.
The `correlated colour temperature' is the temperature of the flbody that is, in a certain well-defined sense, nearest in colour.
casa.colorado.edu /~ajsh/colour/Tspectrum.html   (598 words)

  
 Radiation Laws
Generally, flbody conditions apply when the radiator has very weak interaction with the surrounding environment and can be considered to be in a state of equilibrium.
The primary law governing flbody radiation is the Planck Radiation Law, which governs the intensity of radiation emitted by unit surface area into a fixed direction (solid angle) from the flbody as a function of wavelength for a fixed temperature.
The behavior of flbody radiation is described by the Planck Law, but we can derive from the Planck Law two other radiation laws that are very useful.
csep10.phys.utk.edu /astr162/lect/light/radiation.html   (530 words)

  
 IMSA Geophysics
The principles of flbody radiation are at the heart of both the most simple and the most complex climate models, including the general circulation models (GCMs) which are run on supercomputers and used for predicting global climate change.
A flbody is a theoretical object which is a perfect absorber and emitter of radiation.
The radiation given off by a flbody occurs in a wide range or "spectrum" of wavelengths and, based on careful measurements and quantum theory, Max Planck produced an equation to model the observed flbody radiation curve.
staff.imsa.edu /science/geophysics/Blackbody1.html   (1178 words)

  
 Blackbody Spectrum   (Site not responding. Last check: 2007-11-01)
It is indicated by the red column in the thermometer on the right side, and you can change it by clicking and/or dragging on it with you mouse.
The main graph is the intensity of the radiation of the flbody as a function of the wavelength,
For flbody radiation, this is only a function of the temperature.
lectureonline.cl.msu.edu /~mmp/applist/blackbody/black.htm   (164 words)

  
 Blackbody : Black-body - Wikipedia, the free encyclopedia
Start the Blackbody : Black-body article or add a request for it.
Look for "Blackbody : Black-body" in the Wikimedia Commons, our repository for free images, music, sound, and video.
Promotional articles about yourself, your friends, your company or products; or articles written as part of a marketing or promotional campaign, may be deleted in accordance with our deletion policies.
www.wikipedia.org /wiki/Blackbody_:_Black-body   (178 words)

  
 [No title]
A BLACKBODY is a surface that absorbs all radiant energy falling on it.
The best practical flbody is a small hole in a box with a flened interior, because practically none of the radiation entering such a hole could escape again, and it would be absorbed inside.
A large, heated cavity with a tiny hole is often presented as being excellent approximation to such an ideal flbody.
home.wanadoo.nl /paulschils/07.02.html   (893 words)

  
 Theoretical Development
In 1860, Kirchhoff defined a flbody as a surface that neither reflects or transmits, but absorbs all incident radiation, independent of direction and wavelength.
The closest approximation to a flbody is a cavity with an interior surface at a uniform temperature T
The spectral characteristics of flbody radiation as a function of temperature and wavelength were determined by Wilhelm Wien in 1896.
www.omega.com /literature/transactions/volume1/theoretical2.html   (1339 words)

  
 Wien's Law and Blackbody Radiation
A flbody is a theoretical object that is a perfect emitter and absorber of radiation.
The foundation of flbody radiation lies in the idea that radiation is released from flbodies in the form of "quanta" or little discrete packets of light called photons.
That is, the hotter a flbody becomes, the shorter its wavelength of peak emission becomes.
feps.as.arizona.edu /outreach/bbwein.html   (1045 words)

  
 Blackbody Radiation
The flbody radiation is seen as a remnant of the transparency point at which the expanding universe dropped below about 3000K so that radiation could escape.
A uniform background radiation in the microwave region of the spectrum is observed in all directions in the sky.
It is considered to be the remnant of the radiation emitted at the time the expanding universe became transparent at about 3000 K temperature.
hyperphysics.phy-astr.gsu.edu /hbase/bkg3k.html   (913 words)

  
 Blackbody radiation
Friends for more than 25 years, Dunbar and McMahon shared research findings on how molecules react and begin to fall apart when they are energized by colliding with other molecules or by the introduction of an artificial light source, such as lasers.
The theory that radiation causes the dissociation of a molecule as it gains energy from light and starts to break apart was proposed as early as 1919 by Jean Baptiste Perrin, a French Nobel laureate.
Because pressures in the upper atmosphere are still too great and cause decomposition, this research has particular importance for how molecules act in the extreme low pressure environments in interstellar space, in which perhaps only one molecule may exist in a cubic meter of space.
www.cwru.edu /pubs/cnews/1998/1-29/science.htm   (683 words)

  
 Infrared glossary
The flbody radiates energy in predictable spectral distributions and intensities which are a function of the flbody's absolute temperature.
Reflectance is zero for a flbody, and nearly 100 percent for a highly polished surface.
Transmittance is zero for a flbody and nearly 100 percent for a material like glass in the visible spectrum region.
www.edl-inc.com /infrared%20glossary.htm   (824 words)

  
 Blackbody Radiation
Blackbody radiation is a common phenomenon that probably is familiar to you.
When you see stars of different colors, when you observe an electric heating coil on a stove turn red, or when you observe a lightbulb, you are observing flbody radiation.
A flbody is a device that converts heat into radiant energy.
www.tau.ac.il /~phchlab/experiments/iodine/blackbody_radiation.htm   (211 words)

  
 Low Temperature Blackbody: Model 13132
A recirculating refrigerated bath cools the flbody to approximately the desired temperature, and then a sophisticated electronic control system and an array of thermoelectric coolers control the flbody surface precisely at the setpoint.
The absolute temperature of the flbody may be set directly, or the flbody temperature may be set relative to the temperature of an external optional sensor.
The exit aperture of the flbody is sealed with a 3" diameter ZnSe window, and appropriate plumbing is installed to regulate flow of dry gas through the sealed flbody.
www.sbir.com /blackbody_13132.htm   (853 words)

  
 Molecular Noise and "Blackbody" Radiation
This is exactly the same way that electromagnetic flbody radiation is analyzed, the main difference being that the objective in that case is to quantify radiation from a cavity, rather than pressure inside the cavity.
Diatomic noise is lower by a factor of 0.917 based on the flbody analysis, vs. 0.9565 for the billiard ball approach.
In a cavity, according to conventional sound theory, the continuous spectrum degenerates to the set of discrete frequencies given by equation (2) in the flbody analysis section, which are a function of the cavity dimensions.
www.silcom.com /%7ealudwig/Physics/Noise_floor/Molecular_noise_and_blackbody.htm   (1505 words)

  
 SPI / library / blackbody radiators
Remember that all objects are flbody radiators, and that the spectrum of an object's flbody radiation is determined by the object's temperature, and by its emissivity.
Most of the heat transferred into the room, and to the people in it, is transferred as flbody radiation, and not as a result of the radiator heating the air that is in contact with it, although that certainly does happen as well.
As flbody radiators, they emit considerable amounts of energy (roughly 100 W for an average adult at rest) in the infrared region of the spectrum.
www.x20.org /library/thermal/blackbody.htm   (2936 words)

  
 Glossary of Heat Transfer Terms
In other words, the fraction of thermal radiation emitted compared to the amount emitted if the body were a flbody.
By definition, a flbody has a surface emissivity of 1.
The emissivity is also equal to the absorption coefficient, or the fraction of any thermal energy incident on a body that is absorbed.
www.efunda.com /formulae/heat_transfer/home/glossary.cfm   (487 words)

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