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The temperature of a body is increased from $-73^{\circ} \mathrm{C}$ to $327^{\circ} \mathrm{C}$. Then the ratio of emissive power is
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Verified Answer
The correct answer is:
$81$
Radiation from a body $=R$
$R=e \sigma T^4 \times$ time $\times$ area, where $e=$ emissive
power
$\therefore e T^4=$ constant or $e=\left(\frac{\text { constant }}{T^4}\right)$
or $\frac{e_1}{e_2}=\left(\frac{T_2}{T_1}\right)^4$ or $\frac{e_1}{e_2}=\left(\frac{273+327}{273-73}\right)^4$
$=\left(\frac{600}{200}\right)^4=\frac{(3)^4}{1}=\frac{81}{1}$
or $\frac{e_1}{e_2}=\frac{81}{1}$
$R=e \sigma T^4 \times$ time $\times$ area, where $e=$ emissive
power
$\therefore e T^4=$ constant or $e=\left(\frac{\text { constant }}{T^4}\right)$
or $\frac{e_1}{e_2}=\left(\frac{T_2}{T_1}\right)^4$ or $\frac{e_1}{e_2}=\left(\frac{273+327}{273-73}\right)^4$
$=\left(\frac{600}{200}\right)^4=\frac{(3)^4}{1}=\frac{81}{1}$
or $\frac{e_1}{e_2}=\frac{81}{1}$
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