Question

Which one of Cu, Fe and Ag offers great resistance to the flow of electric current?

Answer 1

1. Since the energy required to remove electrons from the valence shell is low for metals, they have mobile or free electrons in their lattice. These electrons can conduct electricity. Therefore, metals are good conductors of electricity.
2. The electrical conductivity of the metals depends on the number of free electrons and their mobility in the lattice. The metal which shows resistance to electric current will have a lower number of free electrons. Out of the given elements, iron $\left(\mathrm{Fe}\right)$ has the lowest number of free electrons compared to copper (Cu) and silver (Ag) and therefore, it will show the highest resistance to electric current.
3. Thus, iron (Fe) offers great resistance to the flow of electric current.