18WuD2x

near ultraviolet • negative exponent 469
near ultraviolet That part of the ultraviolet spectrum
nearest the visible light wavelengths. These
are the least-penetrating ultraviolet rays. They
are also called soft ultraviolet.
near video on demand In television, a local service
in which various programs/videos are broadcast
at specified times.
near zone See NEAR FIELD, 1.
NEB Abbreviation of noise equivalent bandwidth.
NEC Abbreviation of NATIONAL ELECTRIC CODE.
necessary bandwidth The minimum bandwidth
needed (with a given emission) to transmit information
at a required rate and of a required quality.
In general, as data speed increases (as
measured in bits per second, baud, or words per
minute), the minimum required bandwidth increases.
For slow-speed Morse code signals, it
can be as small as a few Hertz; for fast-scan television,
it is several megahertz.
neck The straight portion of a cathode-ray-tube
(CRT) envelope (i.e., the part between the base
and the flared portion).
NEDA Abbreviation of National Electronic Distributors’
Association.
needle 1. The stylus of a phonograph cartridge.
2. The pointer of an indicating meter. 3. One of
the electrodes in a voltage-measuring spark gap
(see NEEDLE GAP). 4. The slender, pointed metal
tip of a test probe.
needle chatter See NEEDLE TALK.
needle drag In disc recording and reproduction,
friction between the needle (stylus) and disc. Also
called stylus drag.
needle electrode See NEEDLE, 3, 4.
needle gap A spark gap composed of two needles
having an adjustable air gap between their
points. An unknown high voltage is measured in
terms of the gap width necessary for sparking.
needle memory A computer memory in which
the dual-state elements are thin magnetic needles.
needle pointer The pointer of a meter or compass.
needle pressure See VERTICAL STYLUS FORCE.
needle probe See NEEDLE-TIP PROBE.
needle scratch In disc recording and reproduction,
noise resulting from vibration of the needle
(stylus) because of an irregular groove surface.
Also called surface noise.
needle talk Direct radiation of sound by the stylus
of a phonograph pickup. Also called needle chatter.
needle telegraph A telegraph in which the Morse
code characters are converted into magnetic needle
deflections.
needle test point See NEEDLE, 4.
needle-tip probe A test probe that terminates in a
sharp point. Also see NEEDLE, 4.
needle voltmeter See NEEDLE GAP.
neg Abbreviation of NEGATIVE.
negate 1. To insert the NOT operation in front of a
digital expression. 2. To change logic 1 to logic 0
(high to low) or vice versa.
negation The logical NOT operation (see NOT) in
digital systems. Also see NAND CIRCUIT, NOR
CIRCUIT, NOR GATE, NOT CIRCUIT, and NOT-
OR CIRCUIT.
negation element In a computer system, a device
that can give the reverse of a condition, event, or
signal.
negative 1. Possessing NEGATIVE ELECTRIFICA-
TION. 2. In voice communications, a word often
used for “no,” especially when interference is present
or signals are weak. 3. Pertaining to a real
number less than zero. 4. An image whose shadings
are opposite to those in the scene.
negative acceleration A decrease in speed or velocity;
also called deceleration.
negative acknowledgment character In a handshaking
or forward-error-correction (FEC) system,
a response by the receiving station that
indicates a missed bit or bits.
negative angle 1. An angle in the third or fourth
quadrant in a system of rectangular coordinates.
2. An angle measured clockwise from the positive
x-axis in a rectangular coordinate system. Compare
POSITIVE ANGLE.
negative bias A steady, negative direct-current voltage
or current applied continuously to an electrode
of a device, such as a transistor to establish
the operating point. Compare POSITIVE BIAS.
negative bus See NEGATIVE CONDUCTOR.
negative charge An electric charge consisting of a
quantity of NEGATIVE ELECTRIFICATION. Also
see CHARGE, 1; ELECTRIC CHARGE; and UNIT
ELECTROSTATIC CHARGE. Compare POSITIVE
CHARGE.
negative conductor The conductor or wire connected
to the negative terminal of a current,
power, or voltage source. Compare POSITIVE
CONDUCTOR.
negative electricity See NEGATIVE CHARGE and
NEGATIVE ELECTRIFICATION.
negative electrification Electrification characterized
by an excess of electrons. For example, when
a glass rod is rubbed with a silk cloth, the cloth
becomes negatively charged because electrons
are transferred from the glass to the cloth. Similarly,
when a neutral atom acquires an extra electron,
the atom becomes negatively charged
because it has an excess of electrons. Compare
POSITIVE ELECTRIFICATION.
negative electrode 1. An electrode connected to
the negative terminal of a current, power, or voltage
source. 2. The negative output terminal of a
current, power, or voltage source, such as a battery
or generator.
negative error of measurement An error of measurement
in which the difference between a measured
value and the true or most probable value
is negative. Compare POSITIVE ERROR OF MEA-
SUREMENT.
negative exponent In mathematical notation, an
exponent indicating that a number is to be raised