Air switch cannot store energy

How much energy is stored in a small air gap?

The small air-gap might be (say) 1mm long and, have an effective volume of 0.02 milli cubic metres. That's a volume ratio of 100:1 (not surprisingly) but, the core might have a relative permeability that is 1000 times that of air hence, 10 times more energy is stored in the air gap. Nice explanation ! :D

Why is air gap a must in a flyback transformer?

And when the switch opens this energy is transferred (partially or fully) to the secondary. Without air gap no energy is stored. So an air gap is a must in a flyback transformer. If we are going to wrap all the windings of transformer to the airgap what happens?

Why do we have more energy in the air gap?

What I know is that the reluctance across the air gap is higher than the reluctance across the core. So if the flux density is constant into the air gap or into the core, we have indeed more energy contained into the air gap because H H is higher.

What is the magnetic voltage drop across the air gap?

Therefore the magnetic voltage drop across the air gap will be 398000/73609 = 5.4 times large in the air gap compared to the core magnetic voltage drop. Or we can use the fact that the flux (the magnetic current) is the same in the caore is is inr the air gap we will have:

How does magnetic fringing affect air gap density?

With small air-gaps, it's pretty reasonable to assume that the flux density in the gap is the same as the flux density in the core. However, as the gap gets bigger, magnetic fringing reduces the flux density in the gap because field lines become more spread out.