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GATE 2017 ME (ME2) – Question 29

Heat Transfer · Boiling and condensation · 1 mark · Multiple choice

A blackbody has emissive power P. When its absolute temperature doubles, its emissive power becomes ______.

  1. 2P
  2. 4P
  3. 8P
  4. 16P

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Correct answer: (D) 16P

Explanation

Stefan–Boltzmann law gives emissive power proportional to absolute temperature to the fourth power. Therefore the ratio is(2T/T)⁴=16 and the new power is **16P, D**. Doubling Celsius temperature would not permit this calculation.