The original post was worded in such a horrid way, probably no one understood what I was asking, I am retyping the questions: Imagine a fixed point in space. that point is between 2 fixed magnets of any strength and orientation as long as some magnetic field is "passing thru" that point. another scenario for E field : imagine a fixed point in space between 2 fixed charges. Some E field passes thru that point too. Now, with different materials placed on that point, I would like to know if all my conclusions below are correct:  EMF, MMF (or dEMF, dMMF)at that point will remain the same no matter what, because EMF MMF are "drivers". "drivers" only relates to the source not the medium  B and D will remain the same, no matter what material is placed on the point. because drivers causes flux. But I am clearly wrong, because flux does require MMF or EMF to divide medium. But how do you get constant flux at a point regardless of material placed on that point?  then H and E will have to be different for different materials ( materials with different mu and epsilon respectively). because if flux densities remain constant, H and E has to change according to material. Or is it other way around? I am asking, because when I studied magnetic circuit, ie. a toroid, I found in horror that, within a toriod, the B is constant thru out the material. but the H's are different when in the core and when in the air gap. The same situations can be found in D and E cases: D will be same across different materials, but E will be reduced in dielectric materials.