# Who Is The Big Brother?

The above shows two spherical planets with different temperatures and sizes. The temperatures of planets A and B are $$9000$$ K and $$3000$$ K, respectively. The radii of planets A and B are $$r$$ and $$3r,$$ respectively. Which of the following statements is correct?

a) The wavelength of the electromagnetic wave that has the largest spectral radiance in the radiation emitted from planet B is three times longer than that from planet A.

b) The radiant energy per unit time and per unit area from planet A is $$81$$ times larger than that from planet B.

c) The total radiant energy per unit time from planet A is $$9$$ times larger than that from planet B.

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