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Question: Answered & Verified by Expert
A rod of length l with thermally insulated lateral surface consists of material whose heat conductivity coefficient varies with temperature as Kx=αT (here α is a positive constant). The ends of the rod are kept at temperature T1 and T2 (T1>T2).



Find the heat current per unit cross-sectional area in the rod
PhysicsThermal Properties of MatterJEE Main
Options:
  • A αllnT1+T2T1
  • B αllnT1T2
  • C αlln2T1T1+T2
  • D αllnT1+T2T2
Solution:
2659 Upvotes Verified Answer
The correct answer is: αllnT1T2


dQdt=-KATx+dx-TxdxI0=-αTAdTdx
    0lI0Aα  dx=-T1T2dTT
    I0lAα=lnT1T2
    I0A=αllnT1T2

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