cause of magnetic field

Similarly the spin of an electron around the nucleus also produces electric current ...and combining all feeble currents.. produced from 2 different sources,atom of an element(here the word element is for Cu,Fe,Al,O,C) has a fixed value of this current or magnetic dipole moment...because 'i' is related to Magnetic dipole moment as :: μ=i(A) ..where A is the area of the circle.

Although the current produced from an atom is very small..but when it comes to .. say 1gram of a ferromagnetic substance...with 10000000000000000000000 atoms on an average, then the combined value of current is enough to produce a magnetic field of about 2-3 Gauss.

i asked why moving charges(current) produce magnetic field

http://www.physicsforums.com/showthread.php?t=175883

http://www.newton.dep.anl.gov/newton/askasci/1993/physics/PHY103.HTM

"Why" questions on the fundamental levels are generally difficult to answer right now. Why does a moving charge create a magnetic field? Why does a charge creates an electric field in the very first place? I don't think anyone will be able to answer that comprehensively. However, to bring to your notice, one can actually figure out a way to write the magnetic field due to a moving point charge: If the charge q is moving with a (non-relativistic) velocity \vec{v}, then the magnetic induction \vec{B} at a point whose position vector relative to the charge is \vec{r} is given by
\vec{B}=\dfrac{\mu_0}{4\pi} \dfrac{q(\vec{v}\times\vec{r})}{r^3}