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 = N2μ0μrA/l
Where N = number of turns
μ0 = Absolute permeability of free space
μr = 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.