Naked Science Forum

General Science => General Science => Topic started by: neilep on 22/09/2008 23:04:44

Title: What Shields Magnets ?
Post by: neilep on 22/09/2008 23:04:44

Dear Magentologists,

Here are some magnets !

 [ Invalid Attachment ]

I bet, as ' magnetologists ' this sexy duo has got your juices flowing eh ?

As a sheepy I of course have just as much charisma and am even more attractive but I am of course not a magnet !!

I was wondering (like ewe do)....is there something , very thin, that I could cover the magnets with that would completely shield magnetic stuff from them ?....Is there some kind of anti-magnetic cloth ?..foil ?...sheet ?

If so, would it be capable of shielding against the strongest magnets ?...


ewe see, it's like this !..I just do not know !!....honestly..I don't !!

Please enlighten me.....I need to know !...and those who donl;t know also want to know too !!

Hugs


neil
Attractive Animal
xxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxx

Title: What Shields Magnets ?
Post by: Pumblechook on 22/09/2008 23:09:48

Mu-metal.   It does come in foil form but how effective it is I do not know..  Thicker the better I would have thought.

Title: What Shields Magnets ?
Post by: neilep on 22/09/2008 23:42:08

Quote from: Pumblechook on 22/09/2008 23:09:48

Mu-metal.   It does come in foil form but how effective it is I do not know..  Thicker the better I would have thought.

Wow !!..thanks Pumblechook

Mu-metal sounds like a curious thing !...what's it all about ?

Title: What Shields Magnets ?
Post by: lyner on 22/09/2008 23:48:39

One way to look at 'magnetic screening' is to treat it rather like an electrical Earth. You need to provide a path for the field lines to follow which is not through the region you want to protect (in the same way that an Earth conducts Electric Current away from /past  the parts it is protecting.
A material like mu metal has a very high permeability and will, effectively, 'grab' the field lines and divert them through itself. If you put something in a mu metal case then the fields inside the case are isolated from the fields outside it.

You can't chop magnetic field lines, you can only divert them.
A well designed magnetic circuit - like a good transformer or a strong magnet - contains most of the field and has as little leakage as possible. Magnetic leakage is a sign of poor efficiency.