Some factors that affect the inductance of a coil include:
1. The inductance is proportional to the square of the number of turns;
2. The inductance increases directly as the permeability of the core material increases;
3. The inductance increases directly as the cross-sectional area increases; and
4. The inductance decreases as its length increases.
7. The permeability of a core material is an indication of the ability of the material to establish a magnetic field.