Two different rods $A$ and $B$ are kept as shown in figure. The ratio of thermal conductivities of $A$ and $B$ is
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$i_{1}=i_{2}$
$\frac{\mathrm{K}_{1} \mathrm{A}(30)}{30}=\frac{\mathrm{K}_{2} \mathrm{A}(35)}{70}$
$\frac{\mathrm{K}_{1}}{\mathrm{K}_{2}}=\frac{1}{2}$
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