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(B) During clear nights,objects on the surface of the Earth radiate heat,causing the temperature to fall. Hence,option $(A)$ is incorrect.According to

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Newton's law of cooling,an approximate form of Stefan's law,is valid only for natural convection

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(B) During clear nights,objects on the surface of the Earth radiate heat,causing the temperature to fall. Hence,option $(A)$ is incorrect.According to Stefan-Boltzmann law,the total energy radiated by a black body per unit time per unit area is $E \propto T^{4}$. Hence,option $(C)$ is incorrect.The energy radiated per second (power) is given by $P = A \sigma \varepsilon T^{4} = 4 \pi r^{2} \sigma \varepsilon T^{4}$.For the two spheres,the ratio of power radiated is:$\frac{P_{1}}{P_{2}} = \left(\frac{r_{1}}{r_{2}}ight)^{2} \left(\frac{T_{1}}{T_{2}}ight)^{4} = \left(\frac{1}{4}ight)^{2} \left(\frac{4000}{2000}ight)^{4} = \frac{1}{16} 	imes (2)^{4} = \frac{16}{16} = 1$.Since $P_{1} = P_{2}$,option $(D)$ is incorrect.Newton's law of cooling is an approximate form of Stefan's law of radiation and is valid for small temperature differences,typically observed in natural convection. Thus,option $(B)$ is correct.

Which of the following statements is true/correct?

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