Question

The heat radiated per unit area in 1 hour by a furnace whose temperature is 3000 K is $\left(\sigma=5.7\times10^{-8}\,W\,m^{-2}\,K^{-4}\right)$

• A. $1.7 x 10^{10}\, J$
• B. $1.1 x 10^{12}\, J$
• C. $2.8 x 10^{8}\, J$
• D. $4.6 x 10^{6}\, J$

Answer 1

Answer: (A)

According to Stefan’s law
$E=\sigma T^{4}$
Heat radiated per unit area in 1 hour $\left(3600s\right)$ is
$= 5.7\times 10^{-8}\times \left(300\right)^{4} \times 3600= 1.7 \times 10^{10} J$