Another way to increase the value of the inductance is to wind the inductor in layers. The inductor in 9.6 (a) is a poor inductor compared to others, because its turns are widely spaced and there are no layers.
The movement of the flow, indicated by a dashed arrow, is not articulated effectively, because there is only one layer of turns. A higher inductance inductor is shown in 9.6 (b). The turns are small in spacing and are wound in two layers.
The two layers interact intensely with one another through the spliced stream, due to the large number of turns. The spire highlighted with the letter x is close to four other (hatching) turns and this causes an increase in the flow interaction.
An inductor may still have greater inductance if it is laid out in layers, as shown in 9.6 (c). Increasing the number of layers (cross-sectional area) greatly improves the interaction of the concatenated flow.
The y-loop is positioned close to six other turns (hatching). In practice several layers may continue to be superimposed continuously. The important fact to remember, is that the inductance of an inductor increases with the addition of the number of layers. Many inductors made differently may have the same inductance.