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Question 30866
JEE Physics · Medium

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

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ConductionMediumQuestion 30866

Question

Two slabs (same area, same thickness) of conductivities k₁ and k₂ are in series. Effective conductivity is:
  1. A
    k₁ + k₂
  2. B
    (k₁k₂)/(k₁+k₂)
  3. C
    2k₁k₂/(k₁+k₂)
    Correct
  4. D
    (k₁+k₂)/2

Correct answer

2k₁k₂/(k₁+k₂)

Explanation

Thermal resistance in series: R = R₁ + R₂. For equal thickness L: k_eff = 2k₁k₂/(k₁+k₂) (harmonic mean).

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