what is the origin of magnetic forces?

Answer 1

Think of it as atomic convergances. In individual atoms, a minute magnetic field is created by the orbits of the electrons. As more atoms line up in relatively the same direction, the many minute fields combine to create a larger one.

When a steel bar is magnetized, (either temporarily by electric current or permenantly through other means), the electrons of the atoms spin around the nucleii in similar directions. Basically, all the electrons spin clockwise, in a plane perpendicular to the magnetic field. Obviously, this is not an absolute condition, but it is relative, which creates the field's strength.

The iron core at the center of the Earth has been aligning it's field for a very long time and on a huge scale. That is why it is so strong and relatively stable, although it is theorized that it has (and will again) entirely reverse it's polarity.

Answer 2

Strictly it is a relativistic effect on moving charge. A magnetic force is actually and electrostatic force between moving charges because the observed charge between moving frames is different.

It is a good example of relativity being important at very low speeds. The drift velocity of electrons in a conductor is a few cm per second, and the relativistic correction due to this is sufficient to give rise to the quite measurable magnetic effect.

Answer 3

Here is a "right-brain" answer. Magnetism seems to be one of the fundamental forces even older than the human mind so origin cannot be assumed.

Answer 4

Moving electric charge.

Answer 5

It is a result of electromagnetic interaction between electrical currents.