What substance blocks a magnetic force best?

That'd be Mu Metal, a dense, relatively soft alloy of approximately 80% nickel, 15% iron, 4% Molybdenum, and trace amounts of manganese, silicon and carbon. Pretty common in electronics applications.

JM: A cheaper opton is transformer steel properly configured or a Helmholtz coil.

Cheers

Joe Meert

A transformer steel lattice cage is cheaper, but he asked what was best ... the coercive effect of Mu Metal is significantly greater.

JM: Of course it is. I was simply giving other options.

Cheers

Joe Meert

Thanks guys. Yes, cheaper is deffinitely better, as well as, ease of purchasing. I am just wanting to do do some experiments with the kids.

Can you tell me what a transformer steel lattice cage is? Is this something I can go to the local electronic parts store to purchase? Thanks

Most of the newer transformers are difficult to disassemble, because they use epoxy to prevent buzzing of the laminations. Long ago most of them were shaped like a letter E, so I suppose they can be woven somewhat like basket weaving. On older color TV sets several square feet of mu metal can be removed easily after you remove the picture tube. Handle the picture tube carefully as it can throw glass shards like a hangranade if it implodes. If the mu metal is really 80% nickel, it may be useful for cold fusion experiments. Neil

That bears repeating. I'd add the capacitors deserve a bit of respect, too.

Buffalo, an electromagnetic lattice cage is more or less a sandwich of numerous thinner plates of suitable steel cocooned in bare copper wire. The effect is sorta akin to a magnetic bottle ... it can be configured "open" to focus or channel a magnetic field, or it can be configured "closed" to contain or exlude a magnetic field. The principle is simple and basic, with a venerable history in electronics and electromechanics, but its also kinda part of the principal on which particle accellerators are built.

I'm looking for a material that is available in sheet form, that is not effected itself by a magnetic force (like aluminum), but is effecient at blocking a magnetic force to the oppisite side (and is easily obtainable). I found a website that has MU metal available in sheets like foil. Does it attract to a magnet?

It should be notably disinclined to do so, and should lessen, in proportion to its own density the effect of a magnet upon normaly magneto-responsive materials .

Indeed it is but the best would be a superconductor material.
They completely exclude magnetic fields.

Good point, Heliotrope ... he did say he was looking for the best.

Thanks for all the inputs. Maybe I should rephrase the original question though. Is there an "easy to find product" that is not attracted to magnets, but acts as a shield for a magnetic force? For instance, I know materials like aluminum and nickle are not attracted to magnets, but they also do not seem to block a magnetic force very well either. I can put magnets on opposite sides of the sheets and they still attract to one another. Is it the density of the material that gives it a "shielding" effect? If so, I am thinking lead would be a good choice.

At my university in the chem. dept. they use superconducting materials to 'super-shield' the NMR magnets, I would have thought if any else cheaper worked - that would be used instead.

Gotta apologize, Buffalo ... I think we all got off to havin' too much fun with this. For what you're looking to accomplish, a bit of Mu Metal foil should suffice, but its gonna be a little pricey. Believe it or not, one of the few places you can obtain small samples of the stuff, at $18.95/linear foot, 3' minimum order, is MicroSoft.

I JUST LOVE THIS WEB SITE! Thanks to all. I just ordered the Mu Metal from the link provided (I hope this was the best deal available - even though shipping IS an additional $20.00). When I get it, we will do our experiments and have some fun. Thanks.

Glad you enjoy it here ... we enjoy havin' folks who enjoy bein' here :cool:

Damn .... hadn't considered the shipping/handling ... prolly shoulda. Sorry. And I dunno of anywhere else you can get small quantities of the stuff, whatever the price, but if you really wanna save some money on it, I know where you can get a helluva deal on 16 gauge industrial stamping-grade 20,000# coils of it, and with 6 or more, you get free dock-to-dock rail shipping.


Oh, along with being dense,that foil is gonna be sorta stiff and have razor-sharp edges ... heavy work gloves would be a good idea.

Do you suppose the mu metal supresses dynamic magnetic fields, but is near worthless for static magnetic fields? Perhaps the high price is almost entirely due to meeting military specs?. At those prices, I suspect the color TV sets use a cheap substitute for mu metal. Part of the problem is we don't manufacture TVs in the USA. Neil