Q97 / 180 · AIIMS 2019 (25 May) · Physics

Calculate radiation power for sphere whose temperature is $227^{\circ} \mathrm{C}$, radius $2 \mathrm{~m}$ and emissivity 0.8 .

  • Correct answer
    A
    $1425 \mathrm{~W}$
  • B
    $1500 \mathrm{~W}$
  • C
    $1255 \mathrm{~W}$
  • D
    $1575 \mathrm{~W}$

Solution

Given, $T=227^{\circ} \mathrm{C}, r=2 \mathrm{~m}, e=0.8$ Radiation power, $P=\sigma \mathrm{AeT}^4$ $\begin{aligned} & =5.67 \times 10^{-8} \times 4 \pi \times(2)^2 \times 0.8 \times(227+273)^4 \\ & \approx 1425 \mathrm{~W}\end{aligned}$

Hence, the correct answer is option: 'A'.

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