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A solid cylinder of radius R made of material of thermal conductivity K_(1) is surrounded by a cylindrical shell of inner radius R and outer radius 2R made of a material of thermal conductivity K_(2). The two ends of the combined system are maintained at two different temperatures . Then there is no loss of heat across the sylinderical surface and the system is in steady state. The effective thermal conductivity of the system is : |
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Answer» `K_(1)+K_(2)` `:.Q_("TOTAL")=Q_(1)+Q_(2)` `rArr(K(4R^(2))d theta)/(dx)=(K_(1)R^(2)d theta)/(dx)` `rArr4K=K_(1)+3K_(2)` `rArrK=(K_(1)+3K_(2))/(4)` So, correct choice is (d). |
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