Question

shown below is the composite rod of metal A and B their thermal coefficient of linear expansion are Alpha 1 and Alpha to their length are L1 in L2 respectively if on heating the length of entire composite rod does not changes then which of the following relation is true​

Answer 1

(3) $\alpha_1.L_1+\alpha_2.L_2=0$

Explanation:

According to given if the length of the composite rod does not changes with increase in temperature then they both behave oppositely equal with the change in temperature.

For the thermal expansion of materials we have the mathematical expression:

$\Delta l=l.\alpha.\Delta T$

where:

$\Delta l=$ change in length

$l=$ initial length

$\alpha=$ coefficient of linear expansion

$\Delta T=$ change in temperature

Now here, as the case is, we have no change in length which means that one substance is expanding while the other is contracting by the same amount with increase in temperature.

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TOPIC: thermal expansion

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