Question

The resistivity of alloy manganin is

• A. Nearly independent of temperature
• B. Increases rapidly with increase in temperature
• C. Decreases with increase in temperature
• D. Increases rapidly with decrease in temperature

Answer 1

Answer: (A)

Nearly independent of temperature

Answer 2

Metals, including alloys, have free electrons as charge carriers. Their movement controls by defects. One of defects of usual metal is oscillations of atoms due to temperature. More temperature - more oscillations - more collisions of electrons with atoms - less mobility - more resistivity. In alloys, like constantan, atoms are in disorder so alloys have big resistivity. Their additional disorder due to temperature increase is insignificant. That is why alloys have no temperature dependence of resistivity. The same picture is with metal glasses.