Inductance is the circuit parameter to describe an inductor. It is an effect which results from the magnetic field that forms around a current carrying conductor. Inductance is symbolized by the letter L, measured in Henry (H), and it is represented graphically as a coiled wire.

Inductance of a coil is given by-

                                                      L = N²μ₀μ_rA/l

                          Where N = number of turns

                        μ₀ = Absolute permeability of free space

                        μ_r =  Relative permeability of core material

                        A = Area of the cross-section of the coil.

                 L = length of the coil

The inductance of the coil is increased by coiling the conductor such that the magnetic flux enclosed (links) all the coils (turns). Additionally, the magnetic flux linking these turns can be increased the conductor around the material with a high permeability.