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A thin copper wire of length L lengthens by 1% when its temperature is raised from T1 to T2. If a thin copper plate of dimensions 2L x L is heated through the same temperature change T1 to T2, what is the percentage change in its area?

1. 1%
2. 2%
3. 3%
4. 4%

Correct answer: 2%

Solution

Fractional area change = 2*alpha*delta_T = 2 times the linear fractional change, so 2 x 1% = 2%.

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