Question

Assertion : The radiation from the sun’s surface varies as the fourth power of its absolute temperature.
Reason : The sun is not a black body.

• A. If both A and R are true, and R is a correct explanation of the A
• B. If both A and R are true, but R is not a correct explanation of the A
• C. If A is true, but R is false
• D. If both A and R are false

Answer 1

Answer: (C)

At as high a temperatrue as $6000K$, the sun acts like a perfect blackbody emitting complete radiation. That’s why the radiation coming from the sun’s surface follows Stefen’s law which states that the energy radiated per unit area per unit time varies as the fourth power of absolute temperature, i.e.
$E=\sigma T^4$