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A uniform rod AB of length 2L is kept with its ends at temperatures differing by 120 degC. A second bent rod PQ of the same cross-section and length 3L/2 is connected across AB as shown. In steady state, what is the approximate temperature difference between P and Q?

1. 60 degC
2. 75 degC
3. 35 degC
4. 45 degC

Correct answer: 45 degC

Solution

P and Q sit at points along AB whose separation corresponds to a fraction of the 120 degC drop; geometry gives a difference of about 45 degC.

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