# Magnetic field re-routing

Can a magnetic field be directed in a particular direction, that is re-route it, such that the magnetic field comes out in only one direction?

• Google mu metal. – Jon Custer Jul 15 '15 at 16:53
• Pretty sure they do something similar in disk electromagnets. – CoilKid Jul 15 '15 at 19:29

Not entirely, but a disk electromagnet works by routing a magnetic field though a ferromagnetic core. It's not a 100% efficient process and you do have a portion that is not directed through the core. The escaped portion is known as flux leakage, and is usually a fairly small percentage of the total field.

From Wikipedia:

The green lines represent magnetic field lines. The closer the lines are to eachother the higher the field density. You can see that most of them pass out the way the designers intended, through the ferromagnetic object, and back into the core C. The white arrows represent the direction of current flow in the coil, and the green arrows represent the polarity of the magnetic field. The lines marked $Bl$ are the flux leakage.

However, I know of no such method or device able to direct magnetic fields with 100% efficiency. There are certain superconductors and metamaterials that show promise, but nothing I know of as yet.

There is a hypothetical elementary particle in particle physics known as a "Magnetic Monopole" (imagine a bar magnet that only has a north pole, or a south pole.) However, as yet, there has been no conclusive experimental evidence that magnetic monopoles exist.

May be of interest:

Georgia State University's science website on Electricity and Magnetism.

Google Scholar search on controlling magnetic fields

Can magnetic fields be redirected and focused at one point? (Physics.stackexchange)

Mu metal

• I agree, except for the topographical map analogy. You have to extrapolate quite a bit to get to your sentence. Nice answer. – WalyKu Jul 17 '15 at 7:23
• @Kurtovic If you had to extrapolate, better just to edit it out. :) – CoilKid Jul 17 '15 at 17:39