18WuD2x

426 magnetic balance • magnetic field intensity
magnet and a magnetic substance. The device
can also be used for measuring the intensity of a
magnetic field, either from a permanent magnet,
an electromagnet, or from the earth.
magnetic bias A steady magnetic force applied to
another magnetic field to set the latter’s quiescent
point (e.g., sensitizing a relay by using a permanent
magnet to lower the relay draw-in point).
magnetic blowout 1. The extinction of an electric
arc by a strong magnetic field. 2. The apparatus
for accomplishing the action described in 1.
magnetic bottle A container envisioned for atomic
fusion reactions, and that would consist of a
magnetic field. Conventional containers cannot
withstand the extremely high temperatures involved
in atomic fusion.
magnetic braking See ELECTROMAGNETIC
BRAKING.
magnetic bridge An instrument comparable to the
WHEATSTONE BRIDGE, used to measure magnetic
permeability.
magnetic bubble memory See BUBBLE MEM-
ORY.
magnetic capacity The maximum magnetization a
given material can receive.
magnetic card A computer storage medium in the
form of a card that can be selectively magnetized
or imprinted with magnetic ink to represent data.
magnetic cartridge A variable-reluctance phonograph
pickup. As the stylus moves in the groove,
the vibrations are translated into electric currents
by a magnet and coil.
magnetic centering Centering the beam in a television
picture tube by means of an electromagnetic
focusing coil, a permanent magnet, or both.
magnetic character A letter, numeral, or other
symbol written or printed in (visible) magnetic ink
for its automatic sensing or reading in computing
and signaling operations.
magnetic circuit The closed path determined by a
line of magnetic flux or by a set of lines of flux.
magnetic clutch A clutch in which the magnetism
of one rotating member causes a second member
to lock in and rotate. There need not be physical
contact between the two.
magnetic coil The winding in an electromagnet or
similar device.
magnetic compass A direction-indicating device
using a horizontally suspended magnetic needle
as the indicator. The needle tends to point in the
direction of the north geomagnetic pole. Compare
GYROCOMPASS.
magnetic component See ELECTROMAGNETIC
COMPONENT.
magnetic conductivity See PERMEABILITY.
magnetic constant The absolute permeability of
free space. It is approximately 1.26 × 10 –6 H/m.
magnetic controller A controller that uses electromagnets
for some of its functions.
magnetic core The iron core of an electromagnet,
choke, transformer, relay, or similar device.
magnetic coupling See INDUCTIVE COUPLING.
magnetic course In navigation, a course referenced
to geomagnetic north, rather than geographic
north.
magnetic crack detector See ELECTROMAG-
NETIC CRACK DETECTOR.
magnetic creeping A gradual increase in the magnetization
of a material under the influence of a
steady magnetizing force.
magnetic cycle 1. For a material in an alternating
magnetic field, the change in magnetic flux as a
function of time. 2. The change in the magneticfield
polarity of the earth. This polarity reverses
every few thousand years.
magnetic damping The production of a damping
effect or drag in a machine or meter by means of
magnetic action on a moving member, in accordance
with LENZ’S LAW.
magnetic declination See DECLINATION.
magnetic deflection See ELECTROMAGNETIC
DEFLECTION.
magnetic density The concentration of magnetic
flux in a region, expressed as the number of lines
per unit area of cross section.
magnetic dip At a particular location on the
earth’s surface, the angle between the terrestrial
magnetic field and a horizontal line.
magnetic dipole 1. A molecule or particle with a
north and south magnetic pole. 2. Any pair of adjacent
north and south magnetic poles.
magnetic direction finder Abbreviation, MDF. A
type of compass operated by an electric signal delivered
by a gyrostabilized magnetic-compass
movement.
magnetic disk A rotating disk coated with a layer
of magnetic material for the recording, storage
and retrieval of information. They are available in
various sizes, configurations, and storage capacities.
Commonly used with personal computers.
Also see DISKETTE and HARD DISK.
magnetic doublet See DOUBLET, 2.
magnetic drive A device in which mechanical
movement is conveyed from one moving part to
another by means of a magnetic clutch.
magnetic drum See DRUM.
magnetic effect of electric current The presence
of a magnetic field around a conductor carrying
electric current.
magnetic equator Also called geomagnetic equator.
An imaginary circle around the earth, along which
a magnetic needle shows no dip. It is near, but
slightly displaced from, the geographic equator,
and is midway between the geomagnetic poles.
magnetic feedback Feedback by means of inductive
coupling between the output and input circuits
of a system. It can be positive or negative.
magnetic field The space around a magnetic pole
or magnetized body in which magnetic energy
acts.
magnetic field intensity See MAGNETIC INTEN-
SITY.