Question

A variety of useful metallic alloys can be prepared by dissolving Ni in Cu. The room temperature resistivity of pure copper is$\mathbf{1}\mathbf{.}\mathbf{6}\mathbf{\times }{\mathbf{10}}^{\mathbf{-}\mathbf{8}}\mathbf{\Omega }\mathbf{.}\mathbf{m}$ . As nickel is dissolved in copper up to 50% mass, the resistivity increases in a nearly linear fashion to the value$\mathbf{47}\mathbf{.}\mathbf{0}\mathbf{\times }{\mathbf{10}}^{\mathbf{-}\mathbf{8}}\mathbf{\Omega }\mathbf{.}\mathbf{m}$ . Explain this increase qualitatively.

Short answer

Adding Ni to the pure Cu creates defects that serve as scattering centers for the electrons. As the number of such centers increases, the mobility of electrons decreases, and the resistivity increases.

Step-by-step solution

Alloys

The homogeneous mixture of metals makes alloys. The usage of alloys plays a major role in our daily life. For example, they are used in locks, wall clocks, artificial magnets, utensils, etc. Copper-nickel alloys are non-corrosive, and extensively, they are used in marine appliances.

Conductivity of metals

Metals are good conductors of heat and electricity. The main reason for their electrical conductivity is due to the presence of free .

Explanation

Adding Ni to the pure Cu creates defects that serve as scattering centers for the electrons. As the number of such centers increases, the mobility of electrons decreases, and the resistivity increases.