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Question 30880
JEE Physics · Hard

Elasticity, Thermal Expansion, Calorimetry and Heat Transfer: Conduction MCQ

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ConductionHardQuestion 30880

Question

In steady state, temperature at midpoint of a composite rod (k₁ = 2k₂) of equal lengths and areas is:
  1. A
    T/3 above cold end
  2. B
    (T_hot + 2T_cold)/3
    Correct
  3. C
    Mid temperature always (T_hot + T_cold)/2
  4. D
    (2T_hot + T_cold)/3

Correct answer

(T_hot + 2T_cold)/3

Explanation

Same Q/t through both. Q = k₁A(T_hot − T_mid)/L = k₂A(T_mid − T_cold)/L. 2(T_hot−T_mid) = T_mid−T_cold → 2T_hot−2T_mid = T_mid−T_cold → T_mid = (2T_hot+T_cold)/3.

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