A,B and C are the three identical conductors but made from different materials. They are kept in contact as shown. Their thermal conductivities are K, 2K and (K)/(2). The free and of A is at 100^(@)C and the free end of C is at 0^(@)C. During steady state, the temperature of the junction of A and B is nearly

A,B and C are the three identical conductors but made from different m

1.	A,B and C are the three identical conductors but made from different materials. They are kept in contact as shown. Their thermal conductivities are K, 2K and (K)/(2). The free and of A is at 100^(@)C and the free end of C is at 0^(@)C. During steady state, the temperature of the junction of A and B is nearly
Answer» `37^(@)C` `71^(@)C` `29^(@)C` `63^(@)C`. Solution :Let R be the THERMAL conductivity of conductor, then thermal conductivity of conductor `B=(R )/(2)` and thermal conductivity of conductor `C=2R`. `:.` HEAT current, `H=(100^(@)-0^(@))/(R+(R)/(2)+2R)=(200)/(7R)` If T. be the temperature of the junction of A and B, then `H=(100-T.)/(R)` or `(200)/(7R)=(100-T.)/(R)` or `T.=(500)/(7)=71^(@)C`. So, CORRECT choice is (b).

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