a magnetic field

[46rossi]

what materials will a magnetic field not pass through.

[theprof]

HyMu80 alloy is another. We've got specialised equipment in my laboratories shielded by it.

[beso]

The answers above are not correct. Magnetic fields pass through all materials. Indeed rather than not passing through mu-metal magnetic fields pass through mu-metal better than any other material.

Magnetic shielding is achieved by using a highly magnetically permiable material like mu-metal to divert the field around the area to be shielded.

There are basicly two types of material when it comes to magnetism. Paramagnetic where the magnetic domains in the material align with an external field. And diamagnetic where the domains align in the opposite direction to the external field. Most materials are diamagnetic.

Ferromagnetic materials are extreme cases of paramagnetism.

[theprof]

You're splitting hairs beso.

Both tonyted and I read the question in terms of screening and we provided answers accordingly. In that context, both answers are correct.

[beso]

theprof:
If the question had said "material that can be used to screen" I would agree. But it said "not pass through".

Screening is a matter of the geometry not the specific material. Using the same geometry any ferromagnetic material can screen. It just takes less mumetal to do it.

The difference is important. I was not splitting hairs at all.