Two identical rods of copper and iron are coa | vedclass

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(A) For rods of identical cross-section and surface area,the length $l$ up to which wax melts is proportional to the square root of the thermal conduc

Vedclass · Accepted Answer

$0.23$

Vedclass · Answer

(A) For rods of identical cross-section and surface area,the length $l$ up to which wax melts is proportional to the square root of the thermal conductivity $K$,i.e.,$l \propto \sqrt{K}$ or $K \propto l^2$.Given:Thermal conductivity of copper $(K_1)$ = $0.92$Length for copper $(l_1)$ = $8.4 \ cm$Length for iron $(l_2)$ = $4.2 \ cm$Using the relation $\frac{K_1}{K_2} = \frac{l_1^2}{l_2^2}$:$K_2 = K_1 	imes \left( \frac{l_2}{l_1} ight)^2$$K_2 = 0.92 	imes \left( \frac{4.2}{8.4} ight)^2$$K_2 = 0.92 	imes \left( \frac{1}{2} ight)^2$$K_2 = 0.92 	imes \frac{1}{4} = 0.23$Therefore,the thermal conductivity of iron is $0.23$.

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