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magnetic field strength • magnetic media 427
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magnetic feedback
magnetic field strength See MAGNETIC INTEN-
SITY.
magnetic-field viewer A device for visually examining
a magnetic field. It consists of a clear plastic
watchcase filled with iron-oxide particles in
liquid suspension. When it is placed within a
magnetic field, the particles align themselves in
the direction of the magnetic lines of flux.
magnetic-film memory A magnetic memory in
which memory cells consist of a thin film (thick
film in some instances) of a magnetic material deposited
on a substrate. Information is written into
and read out of the cell through coils. Also called
thin-film memory.
magnetic flip-flop A bistable multivibrator using
magnetic amplifiers or square-loop cores in place
of transistors.
magnetic flux The intensity of a magnetic field
through a given area. The unit of magnetic flux is
the weber, and the symbol is F. It can loosely be
expressed as the number of lines passing through
a region of a certain area or of a unit area, such
as one square meter. See FLUX.
magnetic flux density See FLUX DENSITY.
magnetic flux linkage The passage of magnetic
lines of flux through separate materials or circuits,
thereby coupling them magnetically.
magnetic focusing See ELECTROMAGNETIC FO-
CUSING.
magnetic force The force exerted by a magnet on a
body of magnetic material, or on another magnet,
within its field.
magnetic friction 1. See HYSTERESIS, 1. 2. The
resistance experienced by a magnetic material
moving in a magnetic field.
magnetic flux
magnetic gap A space separating the materials in
a magnetic circuit. This break is either an air
space or one filled with a comparatively thin piece
of nonmagnetic material (e.g., the gap in a chokecoil
core).
magnetic head See MAGNETIC PICKUP HEAD
and MAGNETIC RECORDING HEAD.
magnetic hysteresis See HYSTERESIS, 1.
magnetic inclination See MAGNETIC DIP.
magnetic induction 1. The magnetization of a
magnetic material, such as iron or steel, when it
is placed in a magnetic field. 2. The induction of
an alternating voltage in a conductor by a nearby
alternating magnetic field. Also see ELECTRO-
MAGNETIC INDUCTION.
magnetic ink Writing or printing ink that is a suspension
of finely divided particles of magnetic
material. Also see MAGNETIC CHARACTER.
magnetic instability 1. The tendency of a magnetic
recording medium to deteriorate with time.
2. Any fluctuation in the intensity of a magnetic
field.
magnetic intensity The free-space strength of a
magnetic field at a particular point. Specifically,
the force (in dynes) that the magnetic field would
exert on a unit magnetic pole placed at that point.
magnetic iron oxide See MAGNETITE.
magnetic leakage The usually undesired extension
of magnetic flux beyond the confines of a
magnetic body, such as the core of a choke.
magnetic lens See ELECTROMAGNETIC LENS.
magnetic line of flux See LINE OF FLUX, 2.
magnetic load An electromagnetic device operating
on the output of an electrical source. Such devices
include actuators, alarms, electromagnets,
magnetic tapes and disks, relays, and loudspeakers.
magnetic loudspeaker See MAGNETIC SPEAKER,
1, 2.
magnetic material 1. A material, such as magnetite,
that exhibits natural magnetism. 2. A material,
such as iron or steel, that is capable of
being magnetized.
magnetic media Any medium that stores data as
tiny magnetic fields; in particular, MAGNETIC
DISK or MAGNETIC TAPE.