Q. A body radiates energy $5W$ at a temperature of $127℃$. If the temperature is increased to $927℃$, then it radiates energy at the rate of
A) $410W$
B) $81W$
C) $405W$
D) $200W$
Explanation
(c) Rate of energy $\frac{Q}{t} = P = A\varepsilon\sigma T^{4} \Rightarrow P \propto T^{4}$
$\Rightarrow \frac{P_{2}}{P_{1}} = \left( \frac{T_{2}}{T_{1}} \right)^{4} = \left( \frac{927 + 273}{127 + 273} \right)^{4} \Rightarrow P_{1} = 405\ W$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.