A) \[\frac{{{r}_{A}}}{{{r}_{B}}}\]
B) \[\frac{{{r}_{B}}}{{{r}_{A}}}\]
C) \[\frac{{{r}_{A}}}{{{r}_{B}}^{2}}\]
D) \[\frac{{{r}_{B}}^{2}}{{{r}_{A}}^{2}}\]
Correct Answer: B
Solution :
\[\frac{4\pi }{3}{{r}^{3}}\rho c\left( -\frac{dT}{dt} \right)=\sigma 4\pi {{r}^{2}}\left( {{T}^{4}}-T_{0}^{4} \right)\] \[\therefore \] \[\left( -\frac{dT}{dt} \right)=\frac{3\sigma }{\rho rc}\left( {{T}^{4}}-T_{0}^{4} \right)=H\] (say) Ratio of rates of fall of temperature \[\frac{{{H}_{A}}}{{{H}_{B}}}=\frac{{{r}_{B}}}{{{r}_{A}}}\]You need to login to perform this action.
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