A magnetic field is a vector field responsible for generating
forces on electrically charged objects and magnets. Magnetic
fields are generated by magnetic dipoles, moving electric
charges, or changing electric fields. Magnetic fields are linked
to electric fields; light, for instance, is a propagating
electric and magnetic wave. Relativistically, a magnetic force
in one inertial frame corresponds to an electric force in
another. When trying to determine the magnetic forces and
fields, the right hand rule often proves useful. Earth's
Magnetic Field The magnetic field of Earth is directional nearly
north-to-south, although slightly askance, meaning that
"magnetic north" is not the same as "true north," and a person
who is orienteering must take into account this change of
declination, although it is truly only marginally relevant,
unless you are close to either pole. This field has been
decaying at a rapid rate of about about 5% per century, which
casts doubt on the theory that the Earth is billions of years o