Question

For a black body at temperature \(727^{\circ}C\), its radiating power is 60 watt and temperature of surrounding is \(227^{\circ}C\). If temperature of black body is changed to \(1227^{\circ}C\) then its radiating power will be:

• A. 304 W
• B. 320 W
• C. 240 W
• D. 120 W

Answer 1

The Correct Option is B

$P \propto\left(T^{4}-T_{0}^{4}\right)$
$\frac{P_{2}}{P_{1}}=\frac{(1500)^{4}-(500)^{4}}{(1000)^{4}-(500)^{4}}=\frac{500^{4}\left(3^{4}-1\right)}{500^{4}\left(2^{4}-1\right)} $
$\frac{P_{2}}{60}=\frac{80}{15} $
$\Rightarrow P_{2}=320 \,W$