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 , 2 ~K and K 2 . The free end 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

Step-by-step solution

Let R be the thermal conductivity of conductor, then thermal conductivity of conductor B= R 2 and thermal conductivity of conductor C=2 R . Heat current, H = 100^ -0^ R + R 2 +2 R = 200 7 R If T ^ be the temperature of the junction of A and B, then H = 100- T ^ R or 200 7 R = 100- T ^ R or T ^ = 500 7 =71^ C