Which of the following statements is true/correct?

  • A
    During clear nights,the temperature rises steadily upward near the ground level.
  • B
    Newton's law of cooling,an approximate form of Stefan's law,is valid only for natural convection.
  • C
    The total energy emitted by a black body per unit time per unit area is proportional to the square of its temperature in the Kelvin scale.
  • D
    Two spheres of the same material have radii $1 \ m$ and $4 \ m$ and temperatures $4000 \ K$ and $2000 \ K$ respectively. The energy radiated per second by the first sphere is greater than that radiated per second by the second sphere.

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