Who Is The Big Brother?

Classical Mechanics Level 3

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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