A) 1/8
B) 3/4
C) 2/3
D) 1/2
Correct Answer: D
Solution :
[d] Let \[{{\operatorname{k}}_{1}}\] and \[{{K}_{2}}\]be the thermal conductivities of larger and smaller sphere. For bigger sphere, \[\frac{{{K}_{1}}4\pi {{\left( 3r \right)}^{2}}\times 100}{t/4}=\frac{\frac{4}{3}\pi {{\left( 3r \right)}^{3}}\rho L}{30\times 60}\] For smaller sphere, \[\frac{{{K}_{2}}4\pi {{r}^{2}}\times 100}{t}=\frac{\frac{4}{3}\pi {{r}^{3}}\rho L}{20\times 60}\therefore \frac{{{K}_{1}}}{{{K}_{2}}}=\frac{1}{2}\]You need to login to perform this action.
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