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Question: Answered & Verified by Expert
If two rods of lengths L and 2L, having coefficients of linear expansion α and 2α respectively are connected end-to-end, then find the average coefficient of linear expansion of the composite rod.
PhysicsThermal Properties of MatterAP EAMCETAP EAMCET 2021 (19 Aug Shift 1)
Options:
  • A 3α2
  • B 5α2
  • C 5α4
  • D 5α3
Solution:
2171 Upvotes Verified Answer
The correct answer is: 5α3

δL=αTL

δ2L=2αT2L

The rods are connected end to end means in series, therefore, net change in length after the composition of rods, δnet=δL+δ2L=αTL+4αTL=5αTL

δnet=αeffT3L=δL+δ2LαeffT3L=5αTLαeff=5α3

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