| Topic: |
Science > Physics |
| User: |
"Ass. Cult. Micene" |
| Date: |
03 Jan 2007 05:52:20 PM |
| Object: |
black-body radiation |
hi all,
i found on a book that for the black-body radiation it is:
energy density = sigma*T^4
energy = sigma*T^4*volume
pressure = (sigma*T^4)/3
where sigma is the stefan-boltzmann constant
i have 3 doubts:
1- the corect name is power density or specific power, anyway not energy
2- i guess that in the second and third expressions i should add "/c", where
c is the speed of light
3- i can't understand why ther is "/3" in the third expression
can anyone help me?
thanks
--
luca
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| User: "Phineas T Puddleduck" |
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| Title: Re: black-body radiation |
03 Jan 2007 06:14:34 PM |
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In article <UkXmh.97965$uv5.1274396@twister1.libero.it>,
"*****. Cult. Micene" <--@--.it> wrote:
hi all,
i found on a book that for the black-body radiation it is:
energy density = sigma*T^4
energy = sigma*T^4*volume
pressure = (sigma*T^4)/3
where sigma is the stefan-boltzmann constant
i have 3 doubts:
1- the corect name is power density or specific power, anyway not energy
2- i guess that in the second and third expressions i should add "/c", where
c is the speed of light
3- i can't understand why ther is "/3" in the third expression
can anyone help me?
thanks
http://hyperphysics.phy-astr.gsu.edu/hbase/mod6.html
http://en.wikipedia.org/wiki/Planck's_law_of_black_body_radiation
--
This space reserved for Jeff Relf's 5-dimensional metric.
--
Posted via a free Usenet account from http://www.teranews.com
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| User: "Luca" |
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| Title: Re: black-body radiation |
03 Jan 2007 06:53:31 PM |
|
|
hi all,
i found on a book that for the black-body radiation it is:
energy density = sigma*T^4
energy = sigma*T^4*volume
pressure = (sigma*T^4)/3
where sigma is the stefan-boltzmann constant
i have 3 doubts:
1- the corect name is power density or specific power, anyway not energy
2- i guess that in the second and third expressions i should add "/c",
where
c is the speed of light
3- i can't understand why ther is "/3" in the third expression
can anyone help me?
thanks
http://hyperphysics.phy-astr.gsu.edu/hbase/mod6.html
http://en.wikipedia.org/wiki/Planck's_law_of_black_body_radiation
ok thank to these sites i found an error in the book, but i don't find the
expression of the pressure. i don't understand why there is "/3".
thank you
luca
.
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| User: "Phineas T Puddleduck" |
|
| Title: Re: black-body radiation |
03 Jan 2007 07:03:40 PM |
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In article <feYmh.97989$uv5.1275190@twister1.libero.it>,
"Luca" <--@--.it> wrote:
ok thank to these sites i found an error in the book, but i don't find the
expression of the pressure. i don't understand why there is "/3".
thank you
luca
Hint: Degrees of freedom?
--
This space reserved for Jeff Relf's 5-dimensional metric.
--
Posted via a free Usenet account from http://www.teranews.com
.
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| User: "Phineas T Puddleduck" |
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| Title: Re: black-body radiation |
03 Jan 2007 07:06:06 PM |
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In article <phineaspuddleduck-811A93.01033904012007@free.teranews.com>,
Phineas T Puddleduck <phineaspuddleduck@googlemail.com> wrote:
In article <feYmh.97989$uv5.1275190@twister1.libero.it>,
"Luca" <--@--.it> wrote:
ok thank to these sites i found an error in the book, but i don't find the
expression of the pressure. i don't understand why there is "/3".
thank you
luca
Hint: Degrees of freedom?
http://en.wikipedia.org/wiki/Stefan-Boltzmann_law helps you out as well?
--
This space reserved for Jeff Relf's 5-dimensional metric.
--
Posted via a free Usenet account from http://www.teranews.com
.
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| User: "Luca" |
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| Title: Re: black-body radiation |
03 Jan 2007 07:48:00 PM |
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In article <feYmh.97989$uv5.1275190@twister1.libero.it>,
"Luca" <--@--.it> wrote:
ok thank to these sites i found an error in the book, but i don't find
the
expression of the pressure. i don't understand why there is "/3".
thank you
luca
Hint: Degrees of freedom?
http://en.wikipedia.org/wiki/Stefan-Boltzmann_law helps you out as well?
thank you very much for your help
--
Luca
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| User: "Phineas T Puddleduck" |
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| Title: Re: black-body radiation |
03 Jan 2007 07:53:58 PM |
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In article <k1Zmh.97995$uv5.1275858@twister1.libero.it>,
"Luca" <--@--.it> wrote:
In article <feYmh.97989$uv5.1275190@twister1.libero.it>,
"Luca" <--@--.it> wrote:
ok thank to these sites i found an error in the book, but i don't find
the
expression of the pressure. i don't understand why there is "/3".
thank you
luca
Hint: Degrees of freedom?
http://en.wikipedia.org/wiki/Stefan-Boltzmann_law helps you out as well?
thank you very much for your help
No need. I only pointed you to places to find it yourself! I always
figure people like to work the answer out themselves... I don't mean to
be rude, its the way I prefer to work too...
Enjoy thermodynamics - if that is at all possible ;-)
--
This space reserved for Jeff Relf's 5-dimensional metric.
--
Posted via a free Usenet account from http://www.teranews.com
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