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Two identical rods are made of different materials whose thermal conductivities are k1 and k2. They are placed end to end between two heat reservoirs at temperatures Q1 and Q2. The temperature of the junction of the rods is(a) θ1 + θ2/2(b) k1θ1 + k2θ2/k2 + k2(c) k1θ2 + k2θ1/k1 + k2(d) |k1θ1 + k2θ2| / |k1 - k2| |
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Answer» Correct Answer is: (b) k1θ1 + k2θ2/k2 + k2 The given situation is like two resistances in series. We define the heat current I = θ1 - θ2/R As the resistances are in series, they carry the same current. Let θ be the temperature of their junction. I = θ1 - θ/R1 = θ - θ2/R2, where R1 = l/k1A and R2 = l/k2A or θ1 - θ/θ - θ2 = R1/R2 = k2/k1. |
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