A radiator in a domestic heating system operates at a surface temperat

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A radiator in a domestic heating system operates at a surface temperature of 55 C.
Determine the rate at which it emits radiant heat per unit area if it behaves as a black body ?


741333203.jpg


why we did not square the temperature
I mean ( 273 + 55)^4

please I need your help
 

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  • #2
SteamKing
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A radiator in a domestic heating system operates at a surface temperature of 55 C.
Determine the rate at which it emits radiant heat per unit area if it behaves as a black body ?


741333203.jpg


why we did not square the temperature
I mean ( 273 + 55)^4

please I need your help
Because radiation is proportional to the fourth power of the absolute temperature, not the square.

See the Stefan-Boltzmann Law:

http://en.wikipedia.org/wiki/Stefan–Boltzmann_law
 
  • #3
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my question why in the answer we did not say ( ( 273 + 55)^4 ) not ( 273 + 55) without power 4
 
  • #4
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Maybe same reason they did not put the right order of magnitude for the Stefan-Boltzmann constant (10^(-8) in SI units).
It may be simply some typo(s). The result seem to be OK. So they did take the fourth power to get that number.
 
  • #5
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It must to make temperature with power 4 ?
 
  • #6
3,758
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Yes.
 
  • #7
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ok and this value 5.6697 X 10^-8 for what ?
 
  • #8
3,758
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Stefan_Boltzmann constant. Did you even read about Stefan-Boltzmann law of radiation?
 

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