Question

The power of a black body at temperature $200$K is $544$ watt .Its surface area is $(\sigma =5.67$ x ${10}^{-8}w{m}^{-2}{K}^{-4})$

• A. 6 x 10${}^{-2}{m}^2$
• B. 6 m${}^2$
• C. 6 x 10${}^{-6}{m}^2$
• D. 6 x 10${}^2{m}^2$

Answer 1

The correct option is B 6 m${}^2$

We know that: $E=ϵ\sigma A{T}^4$
$A=\frac{E}{\sigma T^4}=\frac{544}{5.67\times {10}^{-8}\times \left({200}^4\right)}=5.99\approx 6{meter}^2$