For q close to zero, induction in the air-gap is minimal (according to demonstration of the answer to question 2 ) and so is field.

For constant solenation in reels, the field is thus minimal, because, according to Ampère's theorem, the following relation exist:

Therefore, the alignment position of the two armatures corresponds to the point in which the core's material saturation is maximum:

It results:

pentru

This corresponds to a core's permeability: