A) 4
B) 16
C) 32
D) 64
Correct Answer: D
Solution :
From Stefans law, \[E=\sigma A{{T}^{4}}=\sigma (4\pi {{R}^{2}}){{T}^{4}}\] or \[\frac{{{E}_{2}}}{{{E}_{1}}}={{\left( \frac{{{T}_{2}}}{{{T}_{1}}} \right)}^{4}}{{\left( \frac{{{R}_{2}}}{{{R}_{1}}} \right)}^{2}}\] \[\therefore \] \[\frac{{{E}_{2}}}{{{E}_{1}}}={{\left( \frac{2T}{T} \right)}^{4}}\times {{\left( \frac{2R}{R} \right)}^{2}}\] \[=16\times 4\] \[=64\] \[\therefore \] \[{{E}_{2}}=64\,{{E}_{1}}\]
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