Understanding Magnetic Fields

[Smith001]

I'm trying to obtain some basic knowledge of magnetic principles.  My question is:  As an iron bar passes in close proximity between two magnets, considering the attraction as the iron bar approaches and departs the magnets, is there energy required other than the motive force required to move the iron bar?  Is the attraction of the iron bar as is passes away from the magnets completely compensated by the attraction of the the iron bar as it approaches the magnets?

Thanks in Advance

[lancaIV]

Probably a help:visit the- mmmgroup.altervista.org-side and read the K.Pullo magnet-motor page,
there is also the possibility to download the -femm.berlios.de- software.

Sincerely
            de Lanca

[magnetoelastic]

Actually it takes MORE energy to pull the iron bar away from the magnet than the magnet imparts to the iron bar in pulling it towards itself.  This is because of magnetic hysteresis.