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Two conductors have equal resistance at 0 deg C but different temperature coefficients of resistance, alpha1 and alpha2. What are, approximately, the effective temperature coefficients of their series and parallel combinations, respectively?

1. (alpha1 + alpha2)/2 and (alpha1 + alpha2)/2
2. (alpha1 + alpha2)/2 and alpha1 + alpha2
3. alpha1 + alpha2 and (alpha1 + alpha2)/2
4. alpha1 + alpha2 and alpha1*alpha2/(alpha1 + alpha2)

Correct answer: (alpha1 + alpha2)/2 and (alpha1 + alpha2)/2

Solution

With equal R0, both the series and parallel combinations have effective coefficient (alpha1 + alpha2)/2.

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