A meter-scale is made of copper and iron rods as shown in the figure. If the length of copper rod is $λ$ meter and the coefficients of linear expansion of copper and iron are $α_{1}$ and $α_{2}$ respectively, then the equivalent coefficient of linear expansion of the combined material of the meterscale is

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Source Q18 diagram

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Answer:

D

Solution:

The two rods expand in series.
$Δ L = λ α_{1} Δ T + (1 - λ) α_{2} Δ T$
$α_{e q} = λ α_{1} + (1 - λ) α_{2}$

TestHub · Accepted Answer

The two rods expand in series. Δ L = λ α 1 ​ Δ T + ( 1 − λ ) α 2 ​ Δ T α e q ​ = λ α 1 ​ + ( 1 − λ ) α 2 ​

Physics - Heat & Thermo Question with Solution | TestHub

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