Question

The radiant energy emitted by a perfect blackbody at $400$K per unit area per second is :

($\sigma =$ 5.7 x 10${}^{-8}$ Wm${}^{-2}$K${}^{-4}$)

• A. 5700 J
• B. 1459 J
• C. 256 J
• D. 1000 J

Answer 1

The correct option is B 1459 J

We know that emissive power is given as: $E=\sigma \epsilon A{T}^4$

$E=5.7\times {10}^{-8}\times {400}^4=1459.2J$