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Two different wires having lengths L_1 and L_2 and respective temperature coefficient of linear expansion α _1 and α _2, are joined end-to-end. Then…

JEE Main 2020 — Physics Thermodynamics

2020mcqmedium

Two different wires having lengths L1{L}_{1}L1​ and L2{L}_{2}L2​ and respective temperature coefficient of linear expansion α1{\alpha }_{1}α1​ and α2,{\alpha }_{2},α2​, are joined end-to-end. Then the effective temperature coefficient of linear expansion is :

Official previous-year question

Held on 5 Sept 2020 · Verified 6 Jul 2026.

Options

  1. A

    α1L1+α2L2L1+L2\frac{{\alpha }_{1}{L}_{1}+{\alpha }_{2}{L}_{2}}{{L}_{1}+{L}_{2}}L1​+L2​α1​L1​+α2​L2​​

  2. B

    2α1α22\sqrt{{\alpha }_{1}{\alpha }_{2}}2α1​α2​​

  3. C

    α1+α22\frac{{\alpha }_{1}+{\alpha }_{2}}{2}2α1​+α2​​

  4. D

    4α1α2α1+α2L2L1(L2+L1)24\frac{{\alpha }_{1}{\alpha }_{2}}{{\alpha }_{1}+{\alpha }_{2}}\frac{{L}_{2}{L}_{1}}{{({L}_{2}+{L}_{1})}^{2}}4α1​+α2​α1​α2​​(L2​+L1​)2L2​L1​​

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