A slender rod of length $L$, diameter $d$ $(L ยป d)$ and thermal conductivity $k_1$ is joined with another rod of identical dimensions, but of thermal conductivity $k_2$, to form a composite cylinderical rod of length $2L$. The heat transfer in radial direction and contact resistance ae negligible. The effective thermal conductivity of the composite rod is

320 Points

100 Points

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