Magnetic Field of Force.
The field of force established by a magnet pole. The attractions and
repulsions exercised by such a field follow the course of the electro-
magnetic lines of force. (See also Field of Force.) Thus the tendency of
a polarized needle attracted or repelled is to follow, always keeping
tangential to curved lines, the direction of the lines of force, however
sweeping they may be. The direction of magnetic lines of force is
assumed to be the direction in which a positive pole is repelled or a
negative one attracted; in other words, from the north pole of a magnet
to its south pole in the outer circuit. The direction of lines of force
at any point, and the intensity or strength of the field at that point,
express the conditions there. The intensity may bc expressed in terms of
that which a unit pole at unit distance would produce. This intensity as
unitary it has been proposed to term a Gauss. (See Weber.)
The direction of the lines of force in a magnetic field are shown by the
time-honored experiment of sprinkling filings of iron upon a sheet of
paper held over a magnet pole or poles. They arrange themselves, if the
paper is tapped, in more or less curved lines tending to reach from one
pole of the magnet to the other. Many figures may be produced by
different conditions. Two near poles of like name produce lines of force
which repel each other. (See Magnetic Curves.)
A magnetic and an electro-magnetic field are identical in all essential
respects; the magnetic field may be regarded as a special form of the
electro-magnetic field, but only special as regards its production and
its defined north and south polar regions.
Synonyms--Magnetic Spin (not much used).
Magnetic Field, Uniform.
A field of identical strength in all parts, such as the earth's magnetic
field. If artificially produced, which can only be approximately done,
it implies large cross-section of magnet pole in proportion to the
length of the magnetic needle affected by it, which is used in
determining its uniformity.
Magnetic Figures.
The figures produced by iron filings upon paper or glass held near
magnetic poles. By these figures the direction of lines of force is
approximately given, and a species of map of the field is shown. (See
Magnetic Field of Force--Magnetic Curves.)
Magnetic Filament.
The successive rows of polarized molecules assumed to exist in
magnetized iron. Each molecule represents an infinitely small magnet,
and its north pole points to the south pole of the next molecule. Such a
string or row is a theoretical conception based on the idea that the
molecules in a magnet are all swung in to parallelism in the magnetizing
process. A magnetic filament may be termed the longitudinal element of a
magnet. (See Magnetism, Hughes' Theory of.)
[Transcriber's note: This description parallels the modern
notion of electron spin as the basis of magnetism in materials.]
Magnetic Fluids.
A two-fluid theory of magnetism has been evolved, analogous to the
two-fluid theory of electricity. It assumes north fluid or "red
magnetism" and a south fluid or "blue magnetism." Each magnetism is
supposed to predominate at its own pole and to attract its opposite.
Before magnetization the fluids are supposed to neutralize each other
about each molecule; magnetization is assumed to separate them,
accumulating quantities of them at the poles.
Magnetic Flux.
Magnetic induction; the number of lines of force that pass through a
magnetic circuit.
Synonym--Magnetic Flow.