Construction of inductor
An inductor is usually constructed as a coil of conducting material, typically opper wire, wrapped around a core either of air or ferrous material.
Core materials with higher permeability than air imprison the magnetic field losely to the inductor, thereby enhancing the inductance. Inductors come in many happens. Most are constructed as enamel coated wire wrapped around a ferrite with wire exposed on the outside, whereas some enclose the wire completely in ferrite and are called shielded'.