CBSE Class 10 Answered

Dear student,

For pure metals, this coefficient is a positive number, meaning that resistance increases with increasing temperature. For the elements carbon, silicon, and germanium, this coefficient is a negative number, meaning that resistance decreases with increasing temperature. For some metal alloys, the temperature coefficient of resistance is very close to zero , meaning that the resistance hardly changes at all with variations in temperature.

Manganin ------- Alloy ------------ +/- 0.000015          
Constantan ----- Alloy --------------- -0.000074   

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