Blackbody radiation - Revision history

Jmdonev: 1 revision imported

2021-09-27T00:02:52Z

1 revision imported

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energy>Ethan.boechler at 18:17, 10 September 2021

2021-09-10T18:17:18Z

← Older revision		Revision as of 18:17, 10 September 2021
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	[[Category:Done 2020-01-31]]		[[Category:Done 2020-01-31]]
			[[Category: Translated to French]]
			[[fr:Rayonnement du corps noir]]
	[[File:Blackbody_spectra.png\|400px\|framed\|right\|Figure 1. Blackbody radiation curves for six different temperatures.<ref>"Blackbody spectra" Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Blackbody_spectra.png#mediaviewer/File:Blackbody_spectra.png</ref>]]		[[File:Blackbody_spectra.png\|400px\|framed\|right\|Figure 1. Blackbody radiation curves for six different temperatures.<ref>"Blackbody spectra" Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Blackbody_spectra.png#mediaviewer/File:Blackbody_spectra.png</ref>]]

	<onlyinclude>'''Blackbody radiation''', sometimes called ''cavity radiation'', refers to the behavior of a [[system]] that absorbs all [[radiation]] that is incident upon it and then re-radiates energy. This re-radiated energy is characteristic of the system and doesn't depend on the energy that is hitting it. The radiated energy depends strongly on the temperature of the object instead.</onlyinclude><ref> Carl R. Nave. (2015, Mar.7). '''HyperPhysics - Blackbody Radiation'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/mod6.html</ref> The object on which the radiation is incident is a special type of object known as a ''blackbody'', a theoretically ideal radiator and absorber, which absorbs all radiation that is incident upon it.<ref> WhatIs.com. (2015, Mar.7). ''Blackbody'' [Online]. Available: http://whatis.techtarget.com/definition/blackbody</ref>		<onlyinclude>'''Blackbody radiation''', sometimes called ''cavity radiation'', refers to the behavior of a [[system]] that absorbs all [[radiation]] that is incident upon it and then re-radiates energy. This re-radiated energy is characteristic of the system and doesn't depend on the energy that is hitting it. The radiated energy depends strongly on the temperature of the object instead.</onlyinclude><ref> Carl R. Nave. (2015, Mar.7). '''HyperPhysics - Blackbody Radiation'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/mod6.html</ref> The object on which the radiation is incident is a special type of object known as a ''blackbody'', a theoretically ideal radiator and absorber, which absorbs all radiation that is incident upon it.<ref> WhatIs.com. (2015, Mar.7). ''Blackbody'' [Online]. Available: http://whatis.techtarget.com/definition/blackbody</ref>

	While there's no such thing as a perfect blackbody, most solid objects are sufficiently close to being a blackbody that they can be treated as ~~being 'close enough'~~. The sun giving off [[sunlight]], for example, can be treated as a perfect blackbody. On the other hand, the Earth needs to have a correction factor. This correction is taken to be a percentage, 70% of a perfect blackbody. This means that the radiation emitted still looks like figure 1, but it is 30% less energy, more or less uniformly across all of the wavelengths. The Earth's atmosphere cannot be treated as a blackbody. Please see [[solar energy to the Earth]] for a more detailed discussion of this.		While there's no such thing as a perfect blackbody, most solid objects are sufficiently close to being a blackbody that they can be treated as one. The sun giving off [[sunlight]], for example, can be treated as a perfect blackbody. On the other hand, the Earth needs to have a correction factor. This correction is taken to be a percentage, 70% of a perfect blackbody. This means that the radiation emitted still looks like figure 1, but it is 30% less energy, more or less uniformly across all of the wavelengths. The Earth's atmosphere cannot be treated as a blackbody. Please see [[solar energy to the Earth]] for a more detailed discussion of this.

	It is difficult to imagine an object that absorbs and emits all wavelengths with equal probability but not equal magnitude. In other words the object would be equally capable of giving off any wavelength of light, it just wouldn't tend to because different wavelengths have different energies. The way physicists often imagine this object is as a hollow metal box with a very small hole in it. This box is in [[thermal equilibrium]] and is filled with radiation that bounces around inside the box, being emitted and reflected by the metallic walls. The tiny hole in one wall of the box allows some of the radiation from in the box to escape. Radiation from outside the box hits the hole and is trapped inside the box and is not likely to be re-emitted from the tiny hole, thus no reflections occur from the blackbody. The only radiation that emerges from the hole is a sample of the radiation bouncing around inside the box.<ref>Kenneth Krane. ''Modern Physics'', 3rd ed. Hoboken, NJ, USA: John Wiley & Sons, 2012.</ref>		It is difficult to imagine an object that absorbs and emits all wavelengths with equal probability but not equal magnitude. In other words the object would be equally capable of giving off any wavelength of light, it just wouldn't tend to because different wavelengths have different energies. The way physicists often imagine this object is as a hollow metal box with a very small hole in it. This box is in [[thermal equilibrium]] and is filled with radiation that bounces around inside the box, being emitted and reflected by the metallic walls. The tiny hole in one wall of the box allows some of the radiation from in the box to escape. Radiation from outside the box hits the hole and is trapped inside the box and is not likely to be re-emitted from the tiny hole, thus no reflections occur from the blackbody. The only radiation that emerges from the hole is a sample of the radiation bouncing around inside the box.<ref>Kenneth Krane. ''Modern Physics'', 3rd ed. Hoboken, NJ, USA: John Wiley & Sons, 2012.</ref>
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	<center><math>\lambda_{peak} \times T = 2.989 \times 10^{-3} mK</math></center>		<center><math>\lambda_{peak} \times T = 2.989 \times 10^{-3} mK</math></center>

	From this and Figure 1 it can be seen that hotter blackbodies emit their peak energies at shorter wavelengths. For blackbodies, both the wavelength at which the body radiates most strongly at ~~- the peak wavelength, found using [[Wiens Law\|Wien's Law]] -~~ and the total amount of radiation of the blackbody~~, depends~~ on its temperature. The total energy radiated by a blackbody is determined from the area of the curve, and the actual value can be determined from the [[Stefan-Boltzmann law]]. As the temperature increases, the total radiation given off by the blackbody increases while the wavelength at which this radiation peaks at becomes smaller (more white or blue light is given off). This dependence on temperature is why stove burners glow red and the Sun glows orange while different stars at a different temperature may have a different colour.		From this and Figure 1 it can be seen that hotter blackbodies emit their peak energies at shorter wavelengths. The peak wavelength can be found using [[Wiens Law]]. For blackbodies, both the wavelength at which the body radiates most strongly at and the total amount of radiation of the blackbody depend on its temperature. The total energy radiated by a blackbody is determined from the area of the curve, and the actual value can be determined from the [[Stefan-Boltzmann law]]. As the temperature increases, the total radiation given off by the blackbody increases while the wavelength at which this radiation peaks at becomes smaller (more white or blue light is given off). This dependence on temperature is why stove burners glow red and the Sun glows orange while different stars at a different temperature may have a different colour.

	For more information on blackbodies, see [http://hyperphysics.phy-astr.gsu.edu/hbase/mod6.html Hyperphysics].		For more information on blackbodies, see [http://hyperphysics.phy-astr.gsu.edu/hbase/mod6.html Hyperphysics].
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	==Phet Simulation==		==Phet Simulation==
	The [http://phet.colorado.edu/ University of Colorado] has graciously allowed us to use the following Phet simulation. Explore this simulation to see ~~changing~~ temperature ~~changes~~ the amount of radiation given by an object~~, and what specific radiation is given off~~:		The [http://phet.colorado.edu/ University of Colorado] has graciously allowed us to use the following Phet simulation. Explore this simulation to see how temperature influences the amount of radiation given off by an object:

	<html><iframe src="https://phet.colorado.edu/sims/html/blackbody-spectrum/latest/blackbody-spectrum_en.html" width="800" height="600" scrolling="no" allowfullscreen></iframe></html>		<html><iframe src="https://phet.colorado.edu/sims/html/blackbody-spectrum/latest/blackbody-spectrum_en.html" width="800" height="600" scrolling="no" allowfullscreen></iframe></html>

Jmdonev: 1 revision imported

2020-01-31T05:10:06Z

1 revision imported

← Older revision	Revision as of 05:10, 31 January 2020
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Energy>Jmdonev at 19:43, 30 January 2020

2020-01-30T19:43:21Z

← Older revision		Revision as of 19:43, 30 January 2020
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	[[Category:Done ~~2019~~-09-05]]		[[Category:Done 2020-01-31]]
	[[File:Blackbody_spectra.png\|400px\|framed\|right\|Figure 1. Blackbody radiation curves for six different temperatures.<ref>"Blackbody spectra" Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Blackbody_spectra.png#mediaviewer/File:Blackbody_spectra.png</ref>]]		[[File:Blackbody_spectra.png\|400px\|framed\|right\|Figure 1. Blackbody radiation curves for six different temperatures.<ref>"Blackbody spectra" Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Blackbody_spectra.png#mediaviewer/File:Blackbody_spectra.png</ref>]]

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	==Blackbody Radiation Curves==		==Blackbody Radiation Curves==
	These blackbodies closely approximate real world objects that are in thermodynamic equilibrium, meaning that they have no net energy flow since the flow in and out has the same rate. As the temperature of the blackbody changes, the curve adjusts and shifts so that the emitted curve balances the absorbed energy.<ref name="astro">Marc L. Kutner. Astronomy: A Physical Perspective, 2nd ed. New York, USA: Cambridge University Press, 2003.</ref> From these curves, you can tell what color or wavelength of light is being emitted by the blackbody. This is done by looking for the ''peak wavelength'' using Wien's displacement law:		These blackbodies closely approximate real world objects that are in thermodynamic equilibrium, meaning that they have no net energy flow since the flow in and out has the same rate. As the temperature of the blackbody changes, the curve adjusts and shifts so that the emitted curve balances the absorbed energy.<ref name="astro">Marc L. Kutner. Astronomy: A Physical Perspective, 2nd ed. New York, USA: Cambridge University Press, 2003.</ref> From these curves, you can tell what color or wavelength of light is being emitted by the blackbody. This is done by looking for the ''peak wavelength'' using [[Wiens Law\|Wien's displacement law]]:

	<center><math>\lambda_{peak} \times T = 2.989 \times 10^{-3} mK</math></center>		<center><math>\lambda_{peak} \times T = 2.989 \times 10^{-3} mK</math></center>

	From this and Figure 1 it can be seen that hotter blackbodies emit their peak energies at shorter wavelengths. For blackbodies, both the wavelength at which the body radiates most strongly at - the peak wavelength, found using [[Wien's Law]] - and the total amount of radiation of the blackbody, depends on its temperature. The total energy radiated by a blackbody is determined from the area of the curve, and the actual value can be determined from the [[Stefan-Boltzmann law]]. As the temperature increases, the total radiation given off by the blackbody increases while the wavelength at which this radiation peaks at becomes smaller (more white or blue light is given off). This dependence on temperature is why stove burners glow red and the Sun glows orange while different stars at a different temperature may have a different colour.		From this and Figure 1 it can be seen that hotter blackbodies emit their peak energies at shorter wavelengths. For blackbodies, both the wavelength at which the body radiates most strongly at - the peak wavelength, found using [[Wiens Law\|Wien's Law]] - and the total amount of radiation of the blackbody, depends on its temperature. The total energy radiated by a blackbody is determined from the area of the curve, and the actual value can be determined from the [[Stefan-Boltzmann law]]. As the temperature increases, the total radiation given off by the blackbody increases while the wavelength at which this radiation peaks at becomes smaller (more white or blue light is given off). This dependence on temperature is why stove burners glow red and the Sun glows orange while different stars at a different temperature may have a different colour.

	For more information on blackbodies, see [http://hyperphysics.phy-astr.gsu.edu/hbase/mod6.html Hyperphysics].		For more information on blackbodies, see [http://hyperphysics.phy-astr.gsu.edu/hbase/mod6.html Hyperphysics].
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	The [http://phet.colorado.edu/ University of Colorado] has graciously allowed us to use the following Phet simulation. Explore this simulation to see changing temperature changes the amount of radiation given by an object, and what specific radiation is given off:		The [http://phet.colorado.edu/ University of Colorado] has graciously allowed us to use the following Phet simulation. Explore this simulation to see changing temperature changes the amount of radiation given by an object, and what specific radiation is given off:

	<html><iframe src="https://phet.colorado.edu/sims/html/blackbody-spectrum/latest/blackbody-spectrum_en.html" width="800" height="600"></iframe></html>		<html><iframe src="https://phet.colorado.edu/sims/html/blackbody-spectrum/latest/blackbody-spectrum_en.html" width="800" height="600" scrolling="no" allowfullscreen></iframe></html>


	The video below gives a historical introduction to how blackbody radiation created quantum mechanics from the brilliant [http://physicsgirl.org/ Physics Girl].		The video below gives a historical introduction to how blackbody radiation created quantum mechanics from the brilliant [http://physicsgirl.org/ Physics Girl].
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	<iframe width="820" height="615" src="https://www.youtube.com/embed/FXfrncRey-4" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe></html>		<iframe width="820" height="615" src="https://www.youtube.com/embed/FXfrncRey-4" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe></html>

			==For Further Reading==
			*[[Halogen light]]
			*[[CFL light bulb]]
			*[[Incandescent light bulb]]
			*[[LED light bulb]]
			*[[Lighting]]
			*Or explore a [[Special:Random\|random page]]

	==References==		==References==
	{{reflist}}		{{reflist}}
	[[Category:Uploaded]]		[[Category:Uploaded]]

Jmdonev: 1 revision imported

2019-09-04T20:39:12Z

1 revision imported

← Older revision	Revision as of 20:39, 4 September 2019
(No difference)

energy>Jmdonev at 19:49, 4 September 2019

2019-09-04T19:49:15Z

← Older revision		Revision as of 19:49, 4 September 2019
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	[[Category:Done ~~2018~~-08-03]]		[[Category:Done 2019-09-05]]
	[[File:Blackbody_spectra.png\|400px\|framed\|right\|Figure 1. Blackbody radiation curves for six different temperatures.<ref>"Blackbody spectra" Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Blackbody_spectra.png#mediaviewer/File:Blackbody_spectra.png</ref>]]		[[File:Blackbody_spectra.png\|400px\|framed\|right\|Figure 1. Blackbody radiation curves for six different temperatures.<ref>"Blackbody spectra" Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Blackbody_spectra.png#mediaviewer/File:Blackbody_spectra.png</ref>]]

Jmdonev at 19:35, 4 September 2019

2019-09-04T19:35:57Z

← Older revision		Revision as of 19:35, 4 September 2019
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	The [http://phet.colorado.edu/ University of Colorado] has graciously allowed us to use the following Phet simulation. Explore this simulation to see changing temperature changes the amount of radiation given by an object, and what specific radiation is given off:		The [http://phet.colorado.edu/ University of Colorado] has graciously allowed us to use the following Phet simulation. Explore this simulation to see changing temperature changes the amount of radiation given by an object, and what specific radiation is given off:

	<html><iframe src="https://phet.colorado.edu/sims/blackbody-spectrum/blackbody-spectrum_en.html" width="800" height="600"></iframe></html>		<html><iframe src="https://phet.colorado.edu/sims/html/blackbody-spectrum/latest/blackbody-spectrum_en.html" width="800" height="600"></iframe></html>

	The video below gives a historical introduction to how blackbody radiation created quantum mechanics from the brilliant [http://physicsgirl.org/ Physics Girl].		The video below gives a historical introduction to how blackbody radiation created quantum mechanics from the brilliant [http://physicsgirl.org/ Physics Girl].

Jmdonev: 1 revision imported

2018-09-03T22:23:37Z

1 revision imported

← Older revision	Revision as of 22:23, 3 September 2018
(No difference)

energy>Jmdonev at 02:54, 13 August 2018

2018-08-13T02:54:05Z

← Older revision		Revision as of 02:54, 13 August 2018
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	[[Category:Done 2018-06-15]]		[[Category:Done 2018-08-03]]
	[[File:Blackbody_spectra.png\|400px\|framed\|right\|Figure 1. Blackbody radiation curves for six different temperatures.<ref>"Blackbody spectra" Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Blackbody_spectra.png#mediaviewer/File:Blackbody_spectra.png</ref>]]		[[File:Blackbody_spectra.png\|400px\|framed\|right\|Figure 1. Blackbody radiation curves for six different temperatures.<ref>"Blackbody spectra" Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Blackbody_spectra.png#mediaviewer/File:Blackbody_spectra.png</ref>]]

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	<html><iframe src="https://phet.colorado.edu/sims/blackbody-spectrum/blackbody-spectrum_en.html" width="800" height="600"></iframe></html>		<html><iframe src="https://phet.colorado.edu/sims/blackbody-spectrum/blackbody-spectrum_en.html" width="800" height="600"></iframe></html>

			The video below gives a historical introduction to how blackbody radiation created quantum mechanics from the brilliant [http://physicsgirl.org/ Physics Girl].

			<html>
			<iframe width="820" height="615" src="https://www.youtube.com/embed/FXfrncRey-4" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe></html>

	==References==		==References==
	{{reflist}}		{{reflist}}
	[[Category:Uploaded]]		[[Category:Uploaded]]

Jmdonev at 05:13, 27 June 2018

2018-06-27T05:13:45Z

← Older revision		Revision as of 05:13, 27 June 2018
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	The [http://phet.colorado.edu/ University of Colorado] has graciously allowed us to use the following Phet simulation. Explore this simulation to see changing temperature changes the amount of radiation given by an object, and what specific radiation is given off:		The [http://phet.colorado.edu/ University of Colorado] has graciously allowed us to use the following Phet simulation. Explore this simulation to see changing temperature changes the amount of radiation given by an object, and what specific radiation is given off:

	<html><iframe src="~~http~~://phet.colorado.edu/sims/blackbody-spectrum/blackbody-spectrum_en.html" width="800" height="600"></iframe></html>		<html><iframe src="https://phet.colorado.edu/sims/blackbody-spectrum/blackbody-spectrum_en.html" width="800" height="600"></iframe></html>
	==References==		==References==
	{{reflist}}		{{reflist}}
	[[Category:Uploaded]]		[[Category:Uploaded]]