What types of materials shield against magnetic forces?

Question

It's for my written report on my science project.

Answer 1

You can't shield against magnetic forces. You can however, reroute magnetic fields but it is tricky to do so. The force that a magnet exerts on a piece of iron is really caused by a non uniform magnetic field. In general, the iron will be pullrd to the point where the magnetic field is greatest. The amount of pul is not a function of the magnetic field strength but rather of how fast the field changes with position.

Iron is drawn to a magnet because of its high magnetic permeability. In simple language, this means that iron and other permeable materials gobble up the magnetic field. This action can reduce the magnetic field near a piece of iron. The other issue is that magnetic fields always make complete loops from a north pole to a south pole.

To shield something from magnetic fields, you must use a permeable material (like iron) that provides a lower resistance path for the field to get from north to south. The best way to do this is to completely enclose the shielded object in a permeable box. Although the explanantion is too involved to go into here, the best shielding is accomplished by using a layered box with complete alternating layers of permeable and non-permeable (air, brass, aluminum, paper) materials.

The selection of the right permeable material and thickness depends on the level of magnetic field being shielded. For high levels, almost any iron material works well with cast iron being very good. For low levels special materials have been developed like mu metal and supermendur that work very well.

Answer 2

Yes, as mentioned above, ferrous metals do a good job, in particular mu metal, though to be accurate, they don't really "shield" but rather provide a low-reluctance path for relatively high field densities, thus "encouraging" flux to not go further.

I should mention that superconductors can actually repel a magnetic field

Answer 3

I know exactly why you need this material..look up "OMNI'S INFINITE ENERGY SOURCE",on utube...its quite simple...if we can negate at least 45% of magnetic push or pull,magnets can be used too create an infinite energy source,the only problem is.."overheating"...if you can find a way too keep cool a power source that is infinite..."youv'e got what you need",other than that,its flawed deeply,The machine would explode causing damage equal too how far the machine went before exploding,which could be anywhere between,one stick of dynamite,and the biggest explosion created by man,but...you would still need materials that could hold up too that amount of power,which we have none of,the only other thing i can think of,is too switch the machine on,and find another way of switching it off.."before it causes damage",I think you'll like this video,"good luck",but remember,there are people who wont allow this sort of tech,until the world stops privatisation...i'm afraid we are stuck with nuclear facility's.

Answer 4

Any Metallic. An earthed aluminium foil will normally do. magnetic fields reduce by the inverse sq. law so a little air gap will also do the job. Unless the magnetic fields are particularly strong.

Answer 5

Nickel Iron and Silicon Iron composites both shield against magnetic fields.

Answer 6

Not aware of any...