Physics
An alloy constantan has resistivity 5 x 10-7 Ω m at 25°C. If the temperature of this alloy is increased to 50°C then its resistivity will be:
- 2.5 x 10-7 Ω m
- 5 x 10-7 Ω m
- 10 x 10-6 Ω m
- 20 x 10-6 Ω m
Calorimetry
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Answer
5 x 10-7 Ω m
Reason — The specific resistance of a substance depends on its temperature but for an alloy of constantan, it remains practically unchanged or constant with change in temperature. So here on increasing the temperature of the alloy, its resistivity does not change much and hence it's final value will be same as initial value i.e., 5 x 10-7 Ω m.
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