Blackbody radiation calculation problem

AI Thread Summary
The discussion centers on calculating the energy radiated by an average person, treated as an ideal blackbody, using the Stefan-Boltzmann law. The relevant equation is L = AσT^4, where A is the skin area, σ is the Stefan-Boltzmann constant, and T is the temperature in Kelvin. Participants clarify that the body temperature should be used as 306 K for radiation and 293 K for absorbed energy. The energy radiated per second is determined by the difference between energy radiated and energy absorbed. Proper application of the temperatures in Kelvin is emphasized for accurate calculations.
LordCalculus
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Blackbody radiation problem!

Homework Statement


The average person has 1.4 m^2 of skin at a skin temperature of roughly 306 K. Consider the average person to be an ideal radiator standing in a room at a temperature of 293 K.

a.) Calculate the energy per second radiated by the average person in the form of blackbody radiation. Express you answer in watts. (How do I treat the temperature?)

Homework Equations



L=AσT^4

Where A = area; σ = Stefan-Boltzmann constant; T = temperature (in Kelvins).

The Attempt at a Solution



L=(1.4)*(5.670400*10^-8)*(?)^4
 
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The energy per second radiated will just be that equation with body temperature as T (~310 Kelvin); but note that this isn't the same as the total energy lost per second.
 


Energy radiated per unit time will be given by Stefan-Boltzman law -

dQ/dt = eAσT^4 (σ - Stefan's constant)

but here 'T' is to be taken in Kelvin and not degree celsius.

and also this is not the energy lost since energy lost = (Energy radiated)-(Energy absorbed)

put T value in the equation. For heat radiated T=306 and for absorbed T=293
 
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