Magnetic Permeability and Shielding

Question

I have two separate understandings of magnetically permeable materials and how they interact with an external magnetic field, and they don't seem to align. Can anyone point out how to connect the two understandings? Particularly in the context of stationary magnetic shielding.

If we imagine a soft iron block fixed to a permanent magnet and measure the flux density magnitude nearby at point A.

1 - Materials with high magnetic permeability such as the iron provide a 'path of least resistance' which the magnetic field 'prefers' Therefore more of the field lines are diverted through the iron and away from point A. Point A is magnetically shielded from the permanent magnet.

2 - The internal magnetic dipoles of materials with high magnetic permeability, in the presence of an external magnetic field, will align more on average. This means the iron block produces its own magnetic field on top of the field produced by the magnet. To me, using this logic, the magnet is made stronger due to the presence of the iron block and the flux density at point A is made larger.

My guess is that the true answer is a combination of both and that the behavior in the first explanation is more dominant than the second? Thanks in advance for any input.

Answer 1

Both understandings can be correct. It depends on the location of point A and the direction of the flux. The iron will "pull" some flux from surrounding areas that are normal to the flux direction (i.e. "off to the side") and will add flux along the original axis of the field. A loose (non-technical) analogy might be something like a venturi.