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Blackbody radiation problem

by LordCalculus
Tags: blackbody, radiation
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LordCalculus
#1
Oct4-10, 02:11 PM
P: 13
1. The problem statement, all variables and given/known data
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?)


2. Relevant equations

L=AσT^4

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

3. The attempt at a solution

L=(1.4)*(5.670400*10^-8)*(????)^4
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zhermes
#2
Oct4-10, 08:54 PM
P: 1,261
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.
gau_physics
#3
Oct23-10, 08:20 AM
P: 12
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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