Permanent Magnets


Joined May 16, 2005
Draw a circle. ;) Flux travels from South to North within a magnet, and from North to South between magnets.

Bonus question for you: Label the N and S poles of the new magnets you will create from soft iron!


Joined Jul 17, 2007
you will have what is called residule magnatizam form in the peacies that would be oposite the polarity they are next too. you can check this with a compass, like the one that lets you know which way is north on the earth. If you break perminate magnet ito peaceses it will go back together forcefully but where they break the polarity will be opposit from where it was, check this with compass also?Be careful with your compass as you can reverse the magnetic polarity of your compass if you get it to close.

Joined Aug 10, 2006
Why is it that most electro_magnetic and magnetostatics theory books try to 'skid away' from permanent magnets and related topics and tend to deal only with electromagnets,
I still really don't know how exactly a magnet is formed? Is there a separate branch / book only about permanent magnets please suggest some


Joined May 4, 2007
Hi Vimal. The entire flux will be contained entirely inside the ring. Ferromagnets will give minimum resistance to flux of permanent magnets. Hence leakage flux will be minimum. Leakage flux will increase as permeability of material comes towards 1 or that of free space.


Joined Dec 23, 2006
I made a request to the Science Channel's "How Its Made" program for Nd-Fe-B magnet manufacture. I think that would be really interesting. I'll post here if I hear anything back from them.
I love that show! I too am interested in that process.:p


Joined Oct 30, 2007
Why is it that most electro_magnetic and magnetostatics theory books try to 'skid away' from permanent magnets and related topics and tend to deal only with electromagnets
The question here has two sides.

The term permanent magnets (hard magnetic materials) is used for materials, that after exposure to high magnetic gains the abillity to produce a magnetic field. This has the destinct advantage that this magnetic field is avalible without any external power source.

The disadvantage of pernament magnets are many: They are difficult to "turn off", they are expencive (though in recent years you can get quite powerfull magnets for reasonable prizes) and lastly, the alloys the magnets are produced from are quite brittle and shatter easily. They also tend to corrode a lot and has to have a protective coating.

Elektromagnets are circuits shaped in a specific fashion (as coild usually), which will produce an electric field when a current is passed through it. The coil can also comprise a magnetic core, which yelds some nice advantages such as better control of the magnetic field and a much smaller required electricpower. They are also easy to turn off and will usually only produce a weak magnetic fielf when off.

The electromagnets has the disadvantage of requireing a constant power source and the needed circuits may be bulky.

The reason why the teacher 'skid away' from permanent magnets is that he is explaining the basics of electromagnetics and will use whatever makes the theory easier. For this reason alone it is often most convinient to use electromagnets, because calculations of electromagnetic circuits with permanent magnets easily become complicated.