A) 1800
B) 900
C) 3600
D) 850
Correct Answer: A
Solution :
Power, \[P=A\varepsilon \sigma {{T}^{4}}\] \[P=\pi {{r}^{2}}\varepsilon \sigma {{T}^{4}}\] \[[\because \,\,A=\pi {{r}^{2}}]\] \[P\propto {{r}^{2}}{{T}^{4}}\] \[\frac{{{P}_{1}}}{{{P}_{2}}}={{\left( \frac{{{r}_{1}}}{{{r}_{2}}} \right)}^{2}}{{\left( \frac{{{T}_{1}}}{{{T}_{2}}} \right)}^{4}}={{\left( \frac{r}{r/2} \right)}^{2}}{{\left( \frac{T}{2T} \right)}^{4}}=\frac{1}{4}\] \[{{P}_{2}}=4\times {{p}_{1}}=4\times 450=1800\,\,W\]
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