MCQ
Two identical metallic balls, whose temperatures are $200^{\circ} C$ and $400^{\circ} C$ respectively, are placed in an enclosure at $27^{\circ} C$. The ratio of heat-loss of the balls will be
  • A
    $1: 4$
  • B
    $\frac{(473)^4-(300)^4}{(673)^4-(300)^4}$
  • C
    $1: 2$
  • D
    $\frac{(200)^4-(27)^4}{(400)^4-(27)^4}$

Answer

(b) $\frac{(473)^4-(300)^4}{(673)^4-(300)^4}$
Explanation: From Stefan Boltzmann's law,
$
\begin{aligned}
& \frac{E_1}{E_2}=\frac{T_1^4-T_0^4}{T_2^4-T_0^4} \\
& =\frac{(273+200)^4-(273+27)^4}{(273+400)^4-(273+27)^4} \\
& =\frac{(473)^4-(300)^4}{(673)^4-(300)^4}
\end{aligned}
$

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