I have a magnetic circuit with the same configuration as in the image, the primary coil has 203 turns and the secondary has 406 turns, how do I get a higher eletromotive force when there is an air gap across the magnetic circuit? If the reluctance is increased and the permeability is reduced shouldn't the emf also be less than without the air gap?
Notice that the primary magnetic field has two places go. The middle iron, and then the iron under the secondary.
Any magnetic field in the middle iron is not coupling to the secondary.
With no air gap (low reluctance), lots more of the magnetic field gets shunted through the middle iron. Resulting in even less magnetic field coupled to the secondary.