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NEET2019PhysicsThermal Properties of MatterActual

One rod of length 2 m and thermal conductivity 50 unit is attached to another rod of length 1 m and thermal conductivity 100 unit. Temperature of free ends are 70^ C and 50^ C respectively. Then temperature of junction point will be

Options

  1. A60^ C
  2. B54^ C
  3. C64^ C
  4. D68^ C

Correct answer

B. 54^ C

Step-by-step solution

Let be the junction temperature, then given situation is shown in the following figure. The rate of heat current due to conduction in both rod will be same, i.e, H ₁= H ₂ aligned K ₁ A ₁ l ₁ & = K ₂ ~A ₂ l ₂ ~K ₁ ₁ l ₁ & = K ₂ ₂ l ₂ 50 (70- ) 2 & =100 ( -50) 1 5 & =270 =54^ C aligned

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