According to Stefan-Boltzmann Law, the energy radiated per unit area per unit time is directly proportional to the fourth power of the absolute temperature of the black body. $E \propto T^4$ $\frac{E_2}{E_1} = \left(\frac{T_2}{T_1}\right)^4$ Given: $E_1 = 7\text{ cal cm}^{-2}\text{s}^{-1}$ $T_1 = 227^{\circ}\text{C} = 227 + 273 = 500\text{ K}$ $T_2 = 727^{\circ}\text{C} = 727 + 273 = 1000\text{ K}$ Substituting the values: $\frac{E_2}{7} = \left(\frac{1000}{500}\right)^4 = 2^4 = 16$ $E_2 = 16 \times 7 = 112\text{ cal cm}^{-2}\text{s}^{-1}$