Magnetic Continuity.
The completeness of a magnetic circuit, as when the armature of a
horseshoe magnet is in contact with both poles. It is an attribute of a
paramagnetic substance only and is identical for permanent magnets or
for electro-magnets. An air space intervening between armature and
magnet poles, or a space filled with any diamagnetic substance prevents
continuity, although the lines of force to some extent still find their
way around. The leakage is increased by discontinuity.
Magnetic Control.
Control of a magnetic needle, magnet, iron index or armature, in a
galvanometer, ammeter or voltmeter by a magnetic field; the restitutive
force being derived from a permanent magnet.
Magnetic Couple.
The couple of magnetic force which tends to bring the magnetic needle
into the plane of the magnetic meridian. One force is represented by the
imaginary pull upon the north pole, and the other by the opposite pull
upon the south pole of the needle. The moment of the couple varies from
a maximum when the needle is at right angles to the plane of the
magnetic meridian to zero when it is in such plane.
Magnetic Creeping.
Viscous hysteresis; the slow increase of magnetism in a paramagnetic
body when exposed to induction.
Fig. 222. MAGNETIC CURVES OR FIGURES.
Magnetic Curves.
The pictorial representation of magnetic lines of force. It is generally
produced by scattering filings on a sheet of paper or pane of glass held
over a magnet. The filings arrange themselves in characteristic curves.
Tapping the paper or pane of glass facilitates the arrangement, or
jarring the filings off a smaller magnet, so that they fall polarized
upon the paper, is thought by some to improve the effect. The group of
curves forms what are termed magnetic figures, q. v.