Question

The resistivity of alloy manganin is
A) Nearly independent of temperature
B) Increase rapidly with increase in temperature
C) Decrease with increase in temperature
D) Increase rapidly with decrease in temperature

Answer 1

The atomic structure of alloys plays an important role in deciding the effect of temperature on the resistivity of alloy. The free electrons are less mobile in alloys. So, they are not affected by the increase in temperature.

Complete step by step solution: -
We know that the conductivity of metals increases with decrease in temperature and the conductivity of semiconductors increases with increase in temperature.

We know that the metal including alloys have free electrons which are charge carriers. Their movement is controlled by some defects. In these defects, one of the defects of usual metal is oscillations of atoms due to the change in temperature. The more temperature results in more oscillations. These increased oscillations result in the collision of electrons with the atoms. In the end, these all result in less mobility. This less mobility turns into more resistivity. In alloys, the atoms are in disorder so alloys have big resistivity. Their additional disorder due to temperature increases becomes insignificant. So, the resistivity of alloys has no temperature dependence.

Hence, the resistivity of alloy manganin is nearly independent of temperature.

Therefore, option A is correct.

Additional Information:- Alloys are the metallic compounds which are the combination of only metals or metals and non-metals. Alloys can be natural and artificial.

Note:- We have to keep in mind that alloys are neither conductors nor insulators. They have a different atomic structure which is not in proper order. If free electrons are more mobile then the resistivity increases and if the free electrons are less mobile then the resistivity decreases.