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MHT CET202124 Sep 2021Morning ShiftPhysicsThermal Properties of MatterActual

A cylindrical rod has temperature ' T ₁ ' and ' T ₂ ' at its ends. The rate of flow of heat is ' Q ₁ ' cal s ⁻¹ . If length and radius of the rod are doubled keeping temperature constant, then the rate of flow of heat ' Q₂ ' will be

Options

  1. AQ ₂= Q ₁ 2
  2. BQ ₂= Q ₁ 4
  3. CQ ₂=4 Q ₁
  4. DQ ₂=2 Q ₁

Correct answer

D. Q ₂=2 Q ₁

Step-by-step solution

aligned & Q ₁= kA ( T ₁- T ₂ ) L ₁ = k r ₁^2 ( ~T ₁- T ₂ ) L ₁ & Q ₂= k r ₂^2 ( ~T ₁- T ₂ ) L ₂ & Q ₂ Q ₁ = r ₂^2 r ₁^2 L ₁ ~L ₂ =(2)^2 1 2 =2 & Q ₂=2 Q ₁ aligned

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