- #1
shyta
- 56
- 0
Hi guys, I need help on my concept on the steffan's law.
I understand that for a grey body sphere confined within a blackbody spherical shell, the general forumla for the net power radiated from inner sphere should be
Prad = kAe(T4-Tsurr4)
where k=stefan boltzman's constant
However recently, I was given a question which made me really confused.
For the case where 2 plates are separated by a gap and the left plate has a higher temp, T1 and emissivity, e1 = 1, as compared to the right plate having T2 and emissivity e2. Then the net rate of power transferred from the left to the right is?
Prad by left plate = kAe1T14
Prad by right plate = kAe2T24
which all of it is absorbed by the left plate since emissivity is 1
then fraction absorbed by right plate is e2
and fraction reflected by right plate is 1-e2(all absorbed by the left plate)
Pnet flow from left to right = kA (e1T14e2 - e2T24)
But how??
I understand that for a grey body sphere confined within a blackbody spherical shell, the general forumla for the net power radiated from inner sphere should be
Prad = kAe(T4-Tsurr4)
where k=stefan boltzman's constant
However recently, I was given a question which made me really confused.
For the case where 2 plates are separated by a gap and the left plate has a higher temp, T1 and emissivity, e1 = 1, as compared to the right plate having T2 and emissivity e2. Then the net rate of power transferred from the left to the right is?
Prad by left plate = kAe1T14
Prad by right plate = kAe2T24
which all of it is absorbed by the left plate since emissivity is 1
then fraction absorbed by right plate is e2
and fraction reflected by right plate is 1-e2(all absorbed by the left plate)
Pnet flow from left to right = kA (e1T14e2 - e2T24)
But how??