Everyone has seen the effect of a magnet and iron filings. They align from one pole of the magnet around to the opposite pole. They become magnets themselves during this process due to their ferromagnetic properties.
This phenomenon is what we have based our understanding of magnetism on for almost 200 years. Maxwell's equations
are derived from this bipolar example. Also, the Biot-Savart
law specifies a magnetic field as a steady distributed current by utilizing the same experiment.
These patterns of iron filings are a representation of the magnets' current, or its "B-field"
In the early 1960's, Dr. Richard Feynman
lectured on the existence of magnetic vector fields. By the mid 1970's, an independent researcher by
the name of Howard Johnson successfully mapped a magnets' vector fields
by using a hall-effect device coupled with a personal computer.
His discovery has led researchers into a new direction in the study of magnetism that he called "Spintronics"
. A variety of new devices have emerged from this electron spin
theory and the calculations of a magnets' A-field.
There is much we can gain from our continued study of magnetism, a most powerful and primal force of nature.
I thought some viewers might enjoy a different look at magnetic lines
of force; take a look at the image gallery and compare that with what
you imagine magnetic force fields look like.