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Question: Answered & Verified by Expert
Calculate radiation power for sphere whose temperature is $227^{\circ} \mathrm{C}$, radius $2 \mathrm{~m}$ and emissivity 0.8 .
PhysicsThermal Properties of MatterAIIMSAIIMS 2019 (25 May)
Options:
  • A $1425 \mathrm{~W}$
  • B $1500 \mathrm{~W}$
  • C $1255 \mathrm{~W}$
  • D $1575 \mathrm{~W}$
Solution:
1318 Upvotes Verified Answer
The correct answer is: $1425 \mathrm{~W}$
Given, $T=227^{\circ} \mathrm{C}, r=2 \mathrm{~m}, e=0.8$
Radiation power, $P=\sigma \mathrm{AeT}^4$
$\begin{aligned} & =5.67 \times 10^{-8} \times 4 \pi \times(2)^2 \times 0.8 \times(227+273)^4 \\ & \approx 1425 \mathrm{~W}\end{aligned}$

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