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MOS capacitor A capacitor using metal-oxide-
or puffing noise sometimes observed in malfunc-
semiconductor (MOS) technology. It is used in
tioning audio circuits. It was so named because
MOS integrated circuits. A silicon substrate
of its resemblance to the sound of a motorboat.
forms one electrode (generally p-type material).
motorboating filter In an audio amplifier
An oxide layer forms the dielectric. An electrode
circuit, a simple filter installed to prevent
forms the other plate of the capacitor. The capac-
458 motorboating filter • M scan

MOTORBOATING caused by unwanted positive mouth The radiating end of a horn (antenna, loud-
feedback. Also see DECOUPLING FILTER. speaker, etc.).
motor capacitor See MOTOR-RUN CAPACITOR MOV Abbreviation of METAL-OXIDE VARISTOR.
motor constant The ability, expressed numeri- movable-coil modulator See ELECTROMECHANI-
cally, of a torque motor to convert electric input CAL MODULATOR.
power into torque. movable contact The traveling contact in a relay
motor converter An electromechanical device for or switch. Compare FIXED CONTACT.
converting alternating current to direct current. movable-iron meter See IRON-VANE METER.
motor-driven relay An electromechanical relay movies on demand In television, a system that
whose contacts are opened and closed by a rotat- makes it possible for subscribers to choose the
ing motor. programs they want to see, and also to choose the
motor effect Magnetic force between adjacent cur- viewing times for the programs.
rent-carrying conductors. moving-coil galvanometer A galvanometer whose
motor-generator A combination of motor and gen- movable element is a coil of fine wire suspended
erator in a single machine assembly. A common or pivoted between the poles of a magnet.
arrangement is a low-voltage motor turning a moving-coil microphone See DYNAMIC MICRO-
high-voltage generator. The machine shafts can PHONE.
be coupled, or the motor can turn the generator moving-coil motor The driving mechanism of a
through a belt, chain, or gear train. moving-coil DYNAMIC SPEAKER.
motor meter A meter in which the movable ele- moving-coil pickup See DYNAMIC PICKUP.
ment is essentially a continuously rotating motor. moving-coil speaker See DYNAMIC SPEAKER.
See, for example, KILOWATT-HOUR METER. moving-conductor microphone See VELOCITY
motor-run capacitor A power-factor-boosting ca- MICROPHONE.
pacitor connected (together with its auxiliary moving-diaphragm meter A headphone used as a
winding) in parallel with the main winding in an sensitive indicator in alternating-current bridge
induction motor. Also see CAPACITOR MOTOR. measurements.
motor-speed control A method of controlling the moving element In an electromechanical device,
speed of a motor by varying the magnitude the portion that moves physically under variable
and/or phase of its current. Electronic devices operating conditions.
usually use diode, diac, or triac circuits. moving-film camera An oscilloscope camera in
motor-start capacitor A capacitor that, with an which the film is drawn past the lens continu-
auxiliary winding, is switched into a motor circuit ously at a constant speed, rather than being ad-
during the starting period, and is automatically vanced frame by frame, as in a motion-picture
disconnected (with the winding) after the motor camera.
reaches normal running speed. Also see CAPACI- moving-iron meter See IRON-VANE METER.
TOR MOTOR. moving-vane meter See IRON-VANE METER.
motor starter See STARTING BOX. mp Abbreviation of MELTING POINT.
mould See MOLD. mp Symbol for MASS OF PROTON AT REST.
mount 1. A mechanical device with which a com- MPEG Abbreviation for MOTION PICTURE EX-
ponent is attached to a circuit board or chassis. PERTS GROUP.
2. The attachment of a circuit board to a MPG Abbreviation of microwave pulse generator.
chassis. 3. The hardware with which an an- mph Abbreviation of miles per hour. Also, mi/h.
tenna is attached to a mast. 4. The hardware MPO Abbreviation of maximum power output.
with which a microphone is attached to a boom mps 1. Abbreviation of meters per second. Also,
or other support. 5. In general, any attaching m/s. 2. Abbreviation of miles per second. Also,
hardware. mi/s.
Mountain standard time Abbreviation, MST. Lo- MPT Abbreviation of MAXIMUM POWER TRANS-
cal mean time at the 105th meridian west of FER.
Greenwich. Also see GREENWICH MEAN TIME, MPX Abbreviation of MULTIPLEX.
mounting flange The portion of a speaker frame, MRIA Abbreviation of Magnetic Recording Industry
usually made of metal, that is equipped with Association.
holes for attachment to a cabinet or panel. mrm Abbreviation of milliroentgens per minute.
mouse A pointing device commonly used with per- MS Abbreviation of MASS SPECTROMETER.
m2/s Abbreviation of meters squared per second.
sonal computers. It is about the size of a candy
bar. The computer operator moves the display The unit of kinematic viscosity.
pointer or cursor by sliding the mouse on a flat M scan In radar operations, a modified A-scan dis-
surface. Functions and commands are executed play in which a pedestal signal is moved along the
by pressing a button (clicking) on the device. base line to a point where it coincides with the
M scan • multiband receiver

base line of the reflected signal to determine the multiband amplifier A radio-frequency power am-
distance to the target. plifier capable of operation on more than one fre-
msec Abbreviation of MILLISECOND. Also, ms. quency band. The bands are often (but not
msg Abbreviation of MESSAGE. always) harmonically related. Compare WIDE-
TION. multiband antenna A single antenna, such as one
MST Abbreviation of MOUNTAIN STANDARD used in amateur radio and television reception,
TIME. operated in several frequency bands or channels.
MT Abbreviation of METRIC TON. The bands are often (but not always) harmoni-
MTR Abbreviation of MAGNETIC TAPE RE- cally related.
mtr Alternate abbreviation of METER.
M-type backward-wave oscillator A broadband, Radiating elements
voltage-tuned oscillator in which the electrons in-
teract with a backward traveling radio-frequency
mu Symbol, µ. 1. Abbreviation of the prefix MI-
CRO-. 2. Expression for AMPLIFICATION Coaxial
feed line
FACTOR. 3. Expression for PERMEABILITY.
4. Expression for MICRON. 5. Expression for ELEC-
7. Expression for MAGNETIC MOMENT. 8. Ex-
µ 1. Symbol for MU.
µA Abbreviation of MICROAMPERE. Radio
µB Symbol for BOHR MAGNETON.
µb Abbreviation of MICROBAR.
µCi Abbreviation of MICROCURIE.
µF Abbreviation of MICROFARAD.
Radiating element
µg Abbreviation of MICROGRAM.
µH Abbreviation of MICROHENRY.
µin Abbreviation of MICROINCH.
µl Abbreviation of MICROLITER.
µmm Abbreviation of micromillimeter (see NANO-
µn Symbol for NUCLEAR MAGNETON. feed line
µP Abbreviation of MICROPROCESSOR. Trans- Radio
µrd Abbreviation of MICRORUTHERFORD. match
µS Abbreviation of MICROSIEMENS.
µs Abbreviation of MICROSECOND. (Also, µsec.)
µV Abbreviation of MICROVOLT.
µV/m Abbreviation of MICROVOLTS PER METER.
µW Abbreviation of MICROWATT. multiband antenna
mu factor See MU, 2. multiband device A device (such as a tuner, re-
mu law In communications, a companding stan- ceiver, transmitter, or test instrument) that oper-
dard generally used in the United States and ates in several selectable frequency bands.
Canada. multiband oscilloscope See WIDEBAND OSCIL-
Muller tube A tube that conducts by means of ion- LOSCOPE.
ization of an internal gas. It is used for radiation multiband receiver A communications receiver
detection. capable of operation on more than one frequency
multiaddress In a computer, a multiple memory band. Such a receiver might, but does not neces-
location. sarily, provide continuous coverage over a wide
460 multiband receiver • multipath transmission

range of frequencies. Compare WIDEBAND RE- multimedia 1. In computing, the use of video,
CEIVER. voice, music, electromechanical control, and/or
multicasting The use of two frequency-modulation data transfer at the same time. Useful in educa-
(FM) broadcast stations, or one FM station and tion, entertainment, business, and gaming appli-
one television station, to broadcast separately the cations. 2. The use of voice, images, data, and/or
two channels of a stereo program. The program is video in a communications system or network,
picked up simultaneously with two receivers. and, in particular, in wireless applications. An ex-
multicavity magnetron A magnetron whose an- ample is videoconferencing between a corporate
ode block has two or more cavities. office and the user of a handheld computer
multicellular horn A loudspeaker in front of which equipped with a wireless modem.
are placed rectangular cells through which the multimedia computer A personal computer de-
sound passes. signed especially for multimedia use. It includes
multichannel Pertaining to a radio-communica- a sound board, speakers, a microphone, and a
tion system that operates on more than one CD-ROM (compact-disk read-only memory) drive.
channel at the same time. The individual chan- It often has a large-screen, high-resolution moni-
nels might contain identical information, or they tor (17 inches or greater diagonal measure).
might contain different signals. multimeter A meter that allows measurement of
multichannel analyzer A test instrument, such as different quantities (e.g., current, voltage, and re-
a spectrum analyzer, that splits an input into sistance); the functions are usually made avail-
several channels for testing. able through a selector switch.
multichannel television sound Abbreviation, multimode operation 1. In radio communication,
MTS. In television broadcasting, audio transmit- the use of two or more transmitters simultane-
ted on more than one channel to provide stereo ously, operating in different modes [e.g., one us-
sound to subscribers. ing single-sideband (SSB) and another using
multichip circuit A MICROCIRCUIT composed of frequency modulation (FM)]. 2. The transmission
interconnected active and passive chip-type com- of visible light or infrared energy through an opti-
ponents. cal fiber in more than one mode at the same time.
multichip integrated circuit An INTEGRATED 3. The operation of any device in more than one of
CIRCUIT composed of circuit elements on sepa- its modes simultaneously.
rate, interconnected chips. multipactor A microwave switching tube capable
multicontact switch A switch having more than of operating at high power levels. Characterized
two contacting positions. by high operating speed.
multicoupler An impedance-matching device used multipath cancellation A phenomenon sometimes
to couple several receivers to a single antenna. observed in radio-wave propagation. Separate sig-
multielement antenna A directive antenna having nal components arrive at the receiver in equal am-
more than one element. Such antennas include plitude, but opposite phase. Also see MULTIPATH
phased arrays and parasitic arrays. Common ex- FADING and MULTIPATH RECEPTION.
amples are the LOG-PERIODIC ANTENNA, the multipath delay In MULTIPATH RECEPTION, the
QUAD ANTENNA, and the YAGI ANTENNA. lag between signal components arriving over dif-
multiemitter transistor 1. A bipolar transistor ferent paths.
having more than one emitter. 2. A bipolar power multipath effect At a receiver, the difference in ar-
transistor having several emitters connected in rival time of multipath signals. Also see MULTI-
parallel in the transistor structure. PATH DELAY.
multiframe A set of frames in a signal that are ad- multipath fading In radio communication, varia-
jacent to each other in time (consecutive) and po- tions in the received signal that result from phas-
sitioned according to an alignment signal. ing various components of the transmitted signal
multigun CRT A cathode-ray tube (CRT) having that are propagated over different paths. At low,
more than one electron gun. medium, and high frequencies, this effect is usu-
multihop propagation Propagation of a radio wave ally the result of ionospheric fluctuation. At very-
by several successive reflections between the high and ultra-high frequencies, it could occur as
ionosphere and the surface of the earth. a result of changes in the state of the intervening
multilayer circuit A circuit consisting of several atmosphere or, occasionally, reflection from ob-
sections printed or deposited on separate layers, jects, such as aircraft.
which are subsequently stacked in a sandwich- multipath reception Reception of a signal over
like manner. more than one path. This often results in fading
multilayer coil A coil in which the turns of wire (see MULTIPATH FADING) and other undesirable
are wound in several complete layers, one on top effects, such as ghosting in television reception.
of the other. Compare SINGLE-LAYER COIL. multipath transmission 1. Transmission of a sig-
multilevel password protection See HIERARCHI- nal over two or more paths. Also see MULTIPATH
multiphase system • multiplex stereo

Ionized layer multiple speakers A group of more than two loud-
speakers, usually operated from a single ampli-
fier system.
multiple-stacked broadside array A stacked ar-
ray in which a number of collinear elements are
stacked above and below each other. Also see
Transmitter Receiver
multiple station Descriptive of a communications
network in which more than one terminal is used.
multiple-unit steerable antenna A shortwave an-
multipath reception
tenna system intended to prevent or minimize the
effects of fading in received signals. It consists
principally of a number of rhombic antennas
multiphase system See POLYPHASE SYSTEM.
feeding the receiver. The system utilizes the vari-
multiple access system A timesharing data pro-
ous waves arriving at different angles. An electric
cessing system that can be used by a number of
steering system causes the antennas to be se-
people at remote locations, usually through pe-
lected automatically in the best combination and
ripherals other than conventional terminals (e.g.,
with their outputs in the proper phase. Also see
cash registers linked to a computer system for in-
ventory control).
multiple winding See DRUM WINDING.
multiple-address code In computer operations, an
multiplex Pertaining to a communications or
instruction code that requires the user to specify
broadcasting system in which multiplexing is
the address of more than one operand per in-
used. See MULTIPLEXING, 1, 2, 3.
multiplex adapter A special circuit (or auxiliary
multiple address instruction A computer pro-
unit) used in frequency-modulated radio re-
gram instruction specifying the address of more
ceivers for stereophonic reception from a station
than one operand.
transmitting a multiplex broadcast. Also see
multiple break 1. Interruption of a circuit at sev-
eral points. 2. Contact bounce.
multiplex code The transmission of multiple sig-
multiple-chip circuit See HYBRID INTEGRATED
nals over a single medium, using a code (such as
Morse, Baudot, or ASCII). See MULTIPLEXING, 2,
multiple connector In a flowchart, a symbol
showing the merging of several flowlines.
multiplex data terminal A computer terminal act-
multiple ionization Successive ionization, as
ing as a modem by virtue of its accepting and
when an ion repeatedly collides with electrons.
transferring signals between its input/output de-
vices and a data channel.
multiple-length number In computer operations,
multiplexer A device that allows two or more sig-
a number occupying more than one register.
nals to be transmitted simultaneously on a single
multiple-loop feedback system A feedback sys-
carrier wave, communications channel, or data
tem using more than one feedback loop. An
channel. See MULTIPLEXING, 2, 3.
example is a tunable audio amplifier (see
multiplexing 1. A process in which a compara-
PARALLEL-TEE AMPLIFIER) in which a negative-
tively low-frequency carrier is modulated, then
feedback path provides tuning, while a positive-
mixed with a signal that has a higher frequency.
feedback path sharpens selectivity.
multiple modulation See COMPOUND MODULA-
neous transmission of numerous relatively
multiple precision arithmetic An arithmetic pro-
low-frequency signals on a single carrier having a
cess using several words (bit groups) for an
higher frequency. Also called frequency-division
operand to ensure accuracy.
multiplexing. 3. The transmission of numerous
multiple programming 1. Computer operation in
signals on a single channel by breaking each sig-
which several programs in memory share periph-
nal into timed fragments (intervals) and transmit-
erals and processor time. 2. Programming a
ting the fragments in a rotating sequence. Also
computer so that several logic or arithmetic
called time-division multiplexing. 4. In certain dig-
operations can be carried out at the same time.
ital light-emitting-diode (LED) displays, the light-
multiple-purpose meter See MULTIMETER.
ing of various parts of the display in a rapidly
multiple-purpose tester A multimeter sometimes
rotating sequence.
combined with some other instrument, such as a
multiplex stereo The use of multiplexing to broad-
test oscillator.
cast both channels of a stereophonic program on
multiple reel file In a data-processing system, a
a single carrier wave. See MULTIPLEXING, 1, 2.
magnetic tape data file of more than one reel.
462 multiplex telegraphy • multiprogramming

Tuned to
f mf
Subcarrier RF
oscillator amplifier

Reactance- Power
Modulator modulated amplifier
+12 V

AF amp. AF amp.

multiplier amplifier

table in Appendix B. Also see, for example,
Subsidiary Main GIGA-, KILO-, MEGA-, MICRO-, MILLI-, NANO-,
input input and PICO-.
multiplier probe 1. A resistor-type test probe for a
multiplexing, 1. voltmeter, which increases the range of the meter
and, therefore, acts as a voltmeter multiplier. 2. A
voltage-multiplier type of test probe for a voltmeter,
multiplex telegraphy 1. A system of wire telegra- which multiplies the test voltage before it is applied
phy in which two or more messages are sent si- to the instrument (e.g., voltage-doubler probe).
multaneously in one or both directions. 2. A multiplier register In a computer, a register that
system of radiotelegraphy in which two or more retains a number during a multiplication opera-
messages can be sent simultaneously on the tion.
same carrier wave. multiplier resistor A resistor connected in series
multiplex telephony 1. A system of wire tele- with a current meter (usually a milliammeter or
phony in which two or more messages can be microammeter) to make it a voltmeter. Also called
sent simultaneously in one or both directions VOLTMETER MULTIPLER.
over the same line. 2. A system of radiotelephony multiplier tube See PHOTOMULTIPLIER TUBE.
in which two or more messages can be sent si- multipoint circuit A transmission circuit or sys-
multaneously on the same carrier wave. tem, in which information can be entered or re-
multiplication 1. The arithmetic process whereby trieved at two or more locations.
a certain factor is added to itself the number of multipoint distribution service In radio broad-
times indicated by another factor (the multiplier). casting, the transmission of programs via mi-
2. A method of increasing a quantity, magnitude, crowave links from a central facility to various
or rate by some desired factor. See, for example, local stations.
FREQUENCY MULTIPLIER and VOLTAGE MUL- multipolar Pertaining to the presence of more than
TIPLIER. two magnetic poles.
multiplier 1. See FREQUENCY MULTIPLIER. multipolar machine A motor or generator having
2. See VOLTAGE MULTIPLIER. 3. A circuit or a number of poles in its armature and field.
device for performing arithmetic multiplication. multiposition relay A relay having more than two
4. See VOLTMETER MULTIPLIER. positions of closure. See, for example, SELECTOR
multiplier amplifier A frequency-multiplying am- RELAY.
plifier (such as a doubler, tripler, or quadrupler), multiposition switch A switch having more than
whose output circuit is tuned to an integral mul- two contacting positions. See, for example, SE-
tiple of the input frequency. Compare STRAIGHT- LECTOR SWITCH and STEPPING SWITCH.
THROUGH AMPLIFIER. multiprocessing 1. In a computer system, the
multiplier phototube See PHOTOMULTIPLIER running of more than one program at once.
TUBE. 2. The use of more than one microprocessor
multiplier prefix A prefix that, when affixed to the simultaneously in a single computer. Also called
name of a quantity (e.g., Hertz and byte) indicates parallel processing. 3. See TIME SHARING.
the amount, usually a power of 10 or a power of multiprogramming Also called multitasking. In a
2, by which that quantity is to be multiplied. Also computer system, a technique that allows two or
called prefix and prefix multiplier. See PREFIXES more programs to be executed at the same time.
multipurpose meter • Musical Instrument Digital Interface

multipurpose meter An electric meter that per-
forms several functions, usually available
through a function selector. Examples: VOLTAM-
multirange instrument An instrument provided
with several separate ranges, usually selectable
by range switching (e.g., five-range voltmeter,
two-scale ammeter, and four-band oscillator).
multisection filter A filter having two or more se-
lective sections connected in cascade.
multisegment magnetron See MULTICAVITY
multiskip propagation See MULTIHOP PROPAGA-
multistage device A device having several stages
operating in cascade or otherwise coordinated
with each other (e.g., a five-stage amplifier).
multistage feedback Feedback (positive or nega-
tive) between several stages in a system, as op-
posed to feedback between the output and input
of a single stage.
multistage oscillation Oscillation resulting from
positive feedback between or among two or more
stages of an amplifier chain, as opposed to oscil-
lation occurring between the output and input of
a single amplifier stage.
multistage X-ray tube An X-ray tube providing multiwire antenna An antenna having more than
electron acceleration by means of successive one wire in the radiating section. In early flat-top
ring-shaped anodes”each biased to a higher antennas, such wires were usually connected to-
voltage than the preceding one. gether at one end.
multiswitch A switch having a number of poles multiwire doublet antenna A doublet antenna
and contacts. having more than one wire in its radiator. A com-
multitester An instrument, such as a multimeter mon form is the folded dipole, in effect two closely
or a combined signal generator and oscilloscope, spaced dipole radiators connected together at
that performs a number of different test func- both ends, one being center-fed.
tions. Mumetal A high-permeability alloy of iron and
multitrack recording 1. A recording on two or nickel, valued especially for use as a magnetic
more tracks (e.g., multitrack disk and multitrack shield for cathode-ray tubes.
tape). 2. Making a recording on a tape or disc Munsell color system A system for specifying col-
with two or more tracks. ors in terms of hue, saturation, and brilliance,
multiturn loop antenna A small loop antenna according to charts. Also see COLOR MATCHING.
(whose diameter measures less than approxi- Muntz metal See YELLOW METAL.
mately 10 degrees of phase in free space) that has MUPO Abbreviation of MAXIMUM UNDISTORTED
two or more turns of wire or tubing. The loop has POWER OUTPUT.
significant inductance. A capacitor, connected in Murray-loop bridge A specialized form of Wheat-
parallel or in series with the loop, can produce a stone bridge in which two of the resistance arms
narrowband frequency response. are supplied by a two-wire line (such as a tele-
multiturn potentiometer A potentiometer whose phone line). By means of resistance measure-
shaft must be rotated through several complete ments made with the bridge, the distance from an
revolutions to cover the full resistance range. office or station to a ground fault on the line can
multivalent Having a valence greater than 2. Com- be determined.
pare UNIVALENT. MUSA Abbreviation of multiple-unit steerable an-
multivibrator A circuit usually containing two tran- tenna.
sistors in a resistance-capacitance (RC) coupled muscovite Formula, KH2Al2(SiO4)3. A high-grade
amplifier, whose output is capacitance-coupled to variety of mica having low dielectric loss.
the input. The two stages switch each other alter- Musical Instrument Digital Interface Acronym,
nately in and out of conduction at a frequency de- MIDI. A computer language used in electronic
termined by the R and C values. Also see ASTABLE music. It “tells” the computer when to play a note,
MULTIVIBRATOR, BISTABLE MULTIVIBRATOR, how long to play it, and how loud to play it. It also
and MONOSTA-BLE MULTIVIBRATOR. sets the tempo of the music, based on how long a
464 Musical Instrument Digital Interface • Mylar

quarter-note lasts. It controls the operation of a stages to accomplish muting. In some cases, the
music synthesizer, and allows two or more syn- audio-frequency circuit is disabled.
thesizers to communicate. mutual antenna coupling Electromagnetic cou-
musical quality See TIMBRE. pling between or among antennas when they are
musical scale A series of tones between a given placed too close together. Usually, it is an unde-
tone and its second harmonic, scaled in intervals sirable phenomenon.
of 1„8 octave. The most common example can be mutual capacitance Inherent capacitance be-
found on a piano. Variations exist (e.g., 13-note tween two conductors.
scale, six-note scale, and five-note scale). mutual-capacitance attenuator An attenuator
music chip An integrated circuit for producing that, in its simplest form, is essentially a
various musical effects (such as tones, percus- shielded, two-plate variable capacitor.
sion, etc.). mutual conductance See TRANSCONDUCTANCE.
music power For a power amplifier, the short-term mutual impedance An impedance shared by two
output power obtained in the reproduction of mu- or more branches of a circuit.
sic waveforms, in contrast to root-mean-square mutual inductance Symbol, M. Unit, henry. The
(rms) or effective power output. property shared by neighboring inductors or in-
music synthesizer A set of oscillators, usually op- ductive devices that enables induction to occur. A
erated with a computer, used to create or playing mutual inductance of 1 henry is present when a
electronic music. Also see MOOG SYNTHESIZER current change of 1 ampere per second in one in-
and MUSIC INSTRUMENT DIGITAL INTERFACE. ductor induces 1 volt across another inductor.
music under Pertaining to low-volume, continu- Also see INDUCTANCE.
ous, background music, often added to presen- mutual-inductance attenuator An attenuator
tations, radio and television advertisements, consisting essentially of two coupled coils (input
educational programs, etc. and output), whose spacing can be gradually
muting 1. Disabling a receiver or amplifier under changed.
no-signal or weak-signal conditions. 2. Softening mutual-inductance bridge See CAREY-FOSTER
or muffling a sound. MUTUAL-INDUCTANCE BRIDGE.
mutual induction The action whereby the mag-
netic field produced by alternating current in one
Amplifier conductor produces a voltage in another isolated
stage conductor.
mutual interference 1. See ADJACENT-
interference between or among radio-frequency
communications circuits.
mutually exclusive events Two or more events (or
data points) so that the occurrence of one pre-
vents the occurrence of the other(s). That is, two
events cannot take place simultaneously.
MV 1. Abbreviation of MEGAVOLT. 2. Abbreviation
mV Abbreviation of MILLIVOLT.
MV Abbreviation of MEDIUM VOLTAGE.
MVA Abbreviation of MEGAVOLT-AMPERE.
mV/m Abbreviation of millivolts per meter.
MW Symbol for MEGAWATT.
mW Symbol for MILLIWATT.
mw Abbreviation of MEDIUM WAVE.
muting circuit 1. An interference-preventing de- MWH Abbreviation of MEGAWATT-HOUR.
vice that automatically shuts off a radio receiver mW RTL Abbreviation of milliwatt resistor-transis-
during the operation of a transmitter, and vice tor logic or low-power resistor-transistor logic.
versa. 2. A squelch circuit. 3. In a stereo receiver, Mx Abbreviation of MAXWELL.
an electronic element that cuts off all audio when Mycalex Trade name for an insulating material
no signal is present or when the receiver is being consisting of mica bonded with glass. Dielectric
constant, 6 to 8. Resistivity, 1013 ohm-cm.
tuned between carriers.
muting switch A switch or relay that cuts off a re- Mylar A DuPont registered trademark. A tough,
ceiver during periods of transmission, or when re- plastic insulating material commonly used as a
ception is not desired. Generally, a cutoff voltage magnetic tape base. Dielectric constant, 2.8 to
is applied to one of the intermediate-frequency 3.7. Dielectric strength, 7000 V/mil.
Mylar capacitor • myriametric waves

Mylar capacitor A capacitor in which the dielectric myogram See ELECTROMYOGRAM.
film is Mylar. myograph See ELECTROMYOGRAPH.
Mylar tape Magnetic recording tape using a Mylar myography See ELECTROMYOGRAPHY.
film as the substrate. myriameter Abbreviation, mym. A metric unit of
linear measure equal to 10 kilometers (104 me-
mym Abbreviation of MYRIAMETER.
myoelectricity 1. Bioelectric pulses of 10- to ters).
1000-mV amplitude produced by muscular activ- myriametric waves British designation for elec-
ity and detectable by electrodes attached to the tromagnetic energy having wavelengths from
skin. Also see ELECTROMYOGRAM, ELEC- 100 kilometers down to 10 kilometers, corre-
TROMYOGRAPH, and ELECTROMYOGRAPHY. 2. sponding to frequencies from 3 kHz up to
The study of phenomena, as defined in 1. 30 kHz.
N 1. Symbol for NUMBER. 2. Symbol for NITRO- A
GEN. 3. Abbreviation for NEWTON. 4. Abbrevia- C
tion of NUMBER (also, No.). 5. Symbol for the set

of natural (counting) numbers (0, 1, 2, 3, . . . ).
n 1. Abbreviation of prefix NANO-. 2. Symbol for
NUMBER. 3. Symbol for a term (e.g., a multiplier) A B C
having an assigned value. 4. Symbol for part of
0 0 1
an expression or operator (as in 2n, n - 1, n2, etc.).
0 1 1
5. Symbol for INDEX OF REFRACTION. 6. Sym-
bol for amount of substance (unit, mole). 1 0 1
NA 1. Abbreviation of not available (as on a specifi-
1 1 0
cations sheet). 2. Abbreviation of not applicable.
Na Symbol for SODIUM.
NAND circuit
nA Abbreviation of NANOAMPERE.
NAB curve In audio-frequency operations, the nanofarad Abbreviation, nF. A unit of capacitance;
1 nF equals 10“9 farad.
standard magnetic tape playback equalization
curve developed by the National Association of nanohenry Abbreviation, nH. A unit of low induc-
tance; 1 nH equals 10“9 henry.
Broadcasters (NAB).
NAE Abbreviation of National Academy of Engineer- nanometer Abbreviation, nm. A unit of short wave-
length or displacement; 1 nm equals 10“9 meter.
NAND circuit Also called NOT-AND circuit. A binary nanosecond Abbreviation, ns. A time interval of
10“9 second.
digital circuit whose output is high (logic 1) if any
of the input signals are low (logic 0); the output is nanotechnology The design and construction of
low only when all the inputs are high. The perfor- superminiature electronic and electromechanical
mance of the NAND circuit is the inverse of that of devices. For example, microscopic, computer-
the AND circuit. controlled robots might someday be used as pro-
NAND gate A gate that performs the function of a grammable antibodies to fight infectious diseases,
NAND circuit. or to build integrated circuits, atom by atom.
nano- Abbreviation, n. A prefix meaning bil- nanovolt Abbreviation, nV. A unit of low voltage;
lionth(s) (i.e., 10“9). 1 nV equals 10“9 volt.
nanoampere Abbreviation, nA. A unit of current; nanovoltmeter A sensitive voltmeter for measur-
1 nA equals 10“9 ampere. ing potential in the nanovolt range.

Copyright © 2001 by The McGraw-Hill Companies, Inc.
Click here for Terms of ®
nanowatt • natural frequency

nanowatt Abbreviation, nW. A unit of low power; the maximum instantaneous frequency deviation
1 nW equals 10“9 watt. is no greater than the highest modulating fre-
nanowattmeter A meter for measuring power in quency.
the nanowatt range. narrowband interference Signal interference
NAP Abbreviation of nuclear auxiliary power. whose bandwidth is narrow, compared with that
napier See NEPER. of the circuit affected.
Napierian base Symbol, e. An irrational number, narrowband voice modulation Abbreviation,
equal to approximately 2.718282, and used as NBVM. A scheme via which an analog voice signal
the NAPIERIAN LOGARITHM base. is compressed into a band of frequencies nar-
Napierian logarithm Abbreviation, ln or loge. A rower than that normally required for effective
logarithm to the base e (see NAPIERIAN BASE). communication.
Also called NATURAL LOGARITHM. Compare narrow bandwidth Pertaining to a radio-frequency
COMMON LOGARITHM. emission whose bandwidth is comparatively nar-
NAPU Abbreviation of nuclear auxiliary power unit. row (e.g., a small fraction of the available spec-
narrative A computer program statement that, trum space in the frequency band being used).
rather then being an instruction, merely de- narrow-sector recorder A directional radio re-
scribes the purpose of what follows (usually the ceiver for locating sources of atmospheric noise.
steps in a routine or a block of instructions) as a NARTB Abbreviation of National Association of Ra-
debugging or program modification aid. In a pro- dio and Television Broadcasters.
gram written in BASIC, such a statement is pre- NAS Abbreviation of National Academy of Sciences.
ceded by the abbreviation REM, for remark. Also National Association of Broadcasters Abbrevia-
called COMMENT. tion, NAB. A countrywide organization of radio
narrowband 1. A frequency band in which the dif- and television broadcasters.
ference between upper and lower limits is small National Bureau of Standards Abbreviation, NBS.
compared with bandwidths typical of the service An agency in the U.S. that maintains values for
specified. 2. Pertaining to a radio-frequency emis- physical constants in the Standard International
sion whose bandwidth is limited or restricted. 3. (SI) System of Units. It also maintains radio
Pertaining to a circuit or device that operates over broadcast stations that transmit standard time
a comparatively small range of frequencies. 4. In and frequency signals.
a digital network, a channel having a bandwidth National Electrical Manufacturers Association
of 64 kbps or less. Abbreviation, NEMA. A countrywide organization
narrowband amplifier An amplifier whose pass- of manufacturers of electrical and electronic
band is restricted to a fraction of the frequency equipment and supplies.
spread common to the amplifier™s application. National Electric Code Abbreviation, NEC. Safety
narrowband FM See NARROWBAND FREQUENCY regulations and procedures issued by the Na-
MODULATION. tional Fire Protection Association for the installa-
narrowband frequency modulation Abbreviation, tion of electrical wiring and equipment in the
NBFM or NFM. Frequency modulation in which United States. Although the code is advisory from
the Association™s standpoint, it is enforced to var-
+12 V ious degrees by local authorities.
National Television Standards Committee Ab-
breviation, NTSC. A U.S. organization of television
companies and other interested organizations. It
developed the original black-and-white and color
television standards that were approved by the
Federal Communications Commission.
natural-decay curve See EXPONENTIAL DE-
Output natural antenna frequency The fundamental res-
onant frequency of an electromagnetic antenna.
natural disintegration 1. The decay of a radioac-
tive substance as a result of the continuous emis-
sion of particles and rays. 2. Also called half life.
The time required for half of a quantity of a ra-
dioactive substance to decay into a different iso-
tope or element.
natural electricity 1. Atmospheric electricity.
2. The electricity in living organisms, that is, BIO-
natural frequency See NATURAL RESONANT
narrowband amplifier FREQUENCY.
468 natural-growth curve • near infrared

natural-growth curve See EXPONENTIAL IN- Nb Symbol for NIOBIUM.
CREASE. nb Abbreviation of NARROWBAND.
natural interference Interference from atmo- NBFM Abbreviation of NARROWBAND FRE-
spheric and celestial sources, as opposed to hu- QUENCY MODULATION. Also abbreviated NFM.
man-made interference. NBS Abbreviation for NATIONAL BUREAU OF
natural language A spoken or written human lan- STANDARDS.
guage (such as French or Japanese), as opposed NBTDR Abbreviation of narrowband time-domain
to a computer language (such as machine lan- reflectometry.
guage, C++, or LISP). Translation between natu- nbw Abbreviation of NOISE BANDWIDTH.
ral language and machine language is important NC 1. Abbreviation of NORMALLY CLOSED. 2. On
in optical character recognition, speech recogni- drawings, abbreviation of no connection. 3. Ab-
tion, and speech synthesis. breviation of NUMERICAL CONTROL.
natural logarithm See NAPIERIAN LOGARITHM. N/C Abbreviation of NUMERICAL CONTROL.
natural magnet A material, such as magnetite nc Abbreviation of no connection.
(lodestone), found in nature and exhibiting per- n-channel junction field-effect transistor Abbre-
manent magnetism. viation, NFET. A junction field-effect transistor in
natural magnetism Magnetism found in some which the gate junction is formed on a bar or die
natural materials (see NATURAL MAGNET) and in of n-type semiconductor material.
the earth itself.
natural number 1. Any nonnegative whole num- Gate
ber, that is, a member of the set N = (0, 1, 2, 3, . . .).
natural period The time required for one complete
wave cycle to occur in a device at its NATURAL
n Drain
natural radiation Noise in the form of radiation
emitted by natural radioactive substances, cosmic
rays, etc. Also called BACKGROUND RADIATION.
n-channel junction field-effect transistor
natural resonance Resonance resulting from the
unique physical constants of a body, circuit, or
system. Also see NATURAL RESONANT FRE- n-channel MOSFET A metal-oxide-semiconductor
QUENCY. (MOS) field-effect transistor in which the channel
natural resonant frequency 1. The frequency at is n-type material.
which a circuit or device responds with maximum NCMT Abbreviation of NUMERICALLY CONTROL-
amplitude to applied signals. 2. The frequency at LED MACHINE TOOL.
which a circuit or device generates maximum en- NCS Abbreviation of net control station(s).
ergy. 3. The frequency at which an object vibrates N curve A negative-resistance voltage-current
at maximum amplitude. curve having a shape roughly resembling an up-
natural wavelength The wavelength correspond- percase letter N. Compare S CURVE.
a circuit, device, or object. N display A radar display in which the target is
nautical mile A nautical unit of linear measure represented by a pair of vertical blips, whose am-
equal to 1.852 kilometers (1.1508 statute miles). plitude indicates target direction and whose posi-
nav 1. Abbreviation of navigation. 2. Abbreviation tion along the horizontal base line (as determined
of navigational. by lining up a pedestal signal with the blips) is
Navaglobe A radionavigation system used at very- read from the pedestal-adjustment calibration.
low or low frequencies over long distances. n-doped zinc-oxide ceramic A nonlinear-
NAVAIDS Abbreviation of NAVIGATIONAL AIDS. resistance material used in the manufacture of
navar A radar system in which a ground radar some voltage-dependent resistors.
scans the immediate vicinity of an airport, ob- NDR Abbreviation of NONDESTRUCTIVE READ.
serves the flight activity, and transmits such ob- NDT Abbreviation of NONDESTRUCTIVE TEST.
servations to aircraft in flight. The name is a Ne Symbol for NEON.
contraction of the term navigation and ranging. near-end crosstalk Crosstalk originating at, or
navigation aid An electronic device or system, near, the telephone subscriber line in which the
such as radar or radio direction finding, that as- interference is noticed.
sists in the navigation of vehicles on land, at sea, near field 1. The radiation field within a radius of
or in the air. 1 wavelength from a transmitting antenna. 2. The
navigation beacon A beam that provides aircraft sound field near a loudspeaker or other repro-
and ships with navigational aid. ducer.
NAWAS Abbreviation of National Attack Warning near infrared Pertaining to electromagnetic radia-
System. tion of 3 to 30 micrometers in wavelength.
near ultraviolet • negative exponent

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

to a negative power. Raising a number x to a neg- positive lead (the usual position). One advantage
ative power “n means taking the reciprocal of the of this arrangement is the lower insulation re-
number raised to the power n. That is, x “n = 1/xn; quirement of the choke.
for example, 10“2 = 1/102 = 1/100 = 0.01. negative light modulation In television image
negative feedback Feedback that is out of phase transmission, the condition in which transmitted
with the input signal. Also called INVERSE FEED- power is increased by a decrease in the initial in-
negative line See NEGATIVE CONDUCTOR.
negative logic 1. Binary logic in which a high neg-
+Vcc ative state represents logic 1, and a low negative
state represents logic 0. 2. Binary logic in which
+ a low positive state represents logic 1, and a high
positive state represents logic 0. Compare POSI-
negative measurement error See NEGATIVE ER-
negative modulation Amplitude-modulated televi-
sion transmission in which the transmitted
power decreases as image brightness increases.
negative modulation factor For an amplitude-
modulated wave having unequal positive and
negative feedback
negative modulation peaks, a ratio expressing the
maximum negative deviation from the average for
the envelope. Compare POSITIVE MODULATION
negative-feedback amplifier An amplifier in
which negative feedback is used to improve per-
negative number A real number less than zero
formance or modify response.
(i.e., one to which the minus sign is assigned).
negative function A trigonometric function having
negative peak The maximum negative instanta-
the negative sign. In a rectangular coordinate
neous current or voltage in an alternating-
system, the sine function is negative in the third
current waveform.
and fourth quadrants, the cosine in the second
negative-peak voltmeter An electronic meter for
and third, and the tangent in the second and
measuring the NEGATIVE PEAK voltage of an al-
fourth. Compare POSITIVE FUNCTION.
ternating-current waveform.
negative gain A misnomer for FRACTIONAL GAIN,
negative phase-sequence relay A relay that re-
arising because fractional gain can be expressed
sponds to the negative phase sequence in a
in negative decibels.
polyphase circuit. Compare POSITIVE PHASE-
negative ghost In a television picture, a ghost with
negative (see NEGATIVE, 4) shading.
negative picture modulation See NEGATIVE
negative ground In a direct-current power system,
the connection of the negative pole to common
negative picture phase In a television signal, the
picture-signal voltage swing from zero to nega-
negative image 1. A picture in which the blacks,
tive, in response to an increase in brightness.
whites, and shades in between are the reverse of
those in the scene (see NEGATIVE, 4). 2. An ab-
negative plate The negative member of a battery
normal image that has the reverse shading de-
cell; electron flow is from the plate through the
scribed in 1.
external circuit.
negative impedance An impedance that displays
negative pole See NEGATIVE ELECTRODE, 1, 2.
the same behavior as that of NEGATIVE RESIS-
negative positive zero Abbreviation, NP0. Pertain-
ing to temperature-compensating capacitors hav-
negative ion An atom with an excess of electrons
ing a temperature coefficient of capacitance that
and, consequently, a net negative charge. Also
changes sign within a specified temperature range.
called ANION. Compare POSITIVE ION.
negative potential 1. The potential measured at a
negative-ion generator A device for generating
negative electrode, with respect to the positive
negative ions and circulating them into the sur-
electrode or to ground. 2. Potential less than that
rounding air. This is believed by some people to
of the earth as a reference.
be beneficial to health.
negative resistance 1. A decrease in voltage across
negative lead See NEGATIVE CONDUCTOR.
a device as the current through it increases, and
negative-lead filtering Power-supply filtering in
an increase in voltage as the current decreases.
which the choke coils and capacitors are in the
2. A decrease in current through a device as the
negative direct-current lead, rather than in the
negative resistance • nemo

voltage across it increases, and an increase in negative space charge The cloud of electrons
current as the voltage decreases. This is opposite to (negative particles) in the region surrounding an
the behavior of an ohmic (positive) resistance. Also emitter, such as the hot cathode of a vacuum
NEGATIVE RESISTOR, and S CURVE. negative temperature coefficient Abbreviation,
NTC. A number expressing the amount by which
a quantity (such as the rating of a component) de-
creases when the temperature is raised. The coef-
ficient is stated as a percentage, or as a certain
number of parts per million (ppm) per degree
Negative temperature rise. Compare POSITIVE TEMPERA-
negative terminal See NEGATIVE ELECTRODE,
+ 2.
Voltage negative torque In an electric motor, a torque that
acts against the operating torque.
negative transmission In a television or facsimile
system, the condition in which brighter light cor-
responds to lower transmitted power, and dimmer
light corresponds to higher transmitted power.
negative valence The valence of a negative ion.
negative resistance
Also see VALENCE.
negator A logical NOT element [i.e., one that out-
puts the complement of an input bit (1 for 0 and
negative-resistance amplifier A simple circuit in
which a negative-resistance device, such as a
negatron The term that specifically differentiates
TUNNEL DIODE, cancels the positive resistance
the familiar ELECTRON from a POSITRON (posi-
of the circuit, causing amplification or oscillation.
tive electron).
negative-resistance device See NEGATIVE RE-
NEI Abbreviation of noise equivalent input.
neighborhood node A local site at which a fiberop-
negative-resistance diode 1. See TUNNEL DIODE.
tic television (video) signal is converted to a cable
2. A reverse-biased germanium diode (and occa-
sionally a silicon diode) that exhibits NEGATIVE
NEL Abbreviation of National Electronics Laboratory.
RESISTANCE. 3. A special diode tube that, when
NELA Abbreviation of National Electric Light Associ-
operated at ultrahigh frequencies, exhibits nega-
tive resistance because of transit-time effects.
N electron In certain atoms, an electron whose or-
negative-resistance magnetron A split-anode
bit is outside of, and nearest to, those of the M
magnetron operated at a combination of anode
voltage and magnetic field strength correspond-
NEMA Abbreviation of National Electrical Manufac-
ing to cutoff; it exhibits negative resistance to
turers™ Association.
voltage applied symmetrically between the anode
nematic crystal A normally transparent liquid
halves. The frequency of oscillation is determined
crystal that becomes opaque when an electric
by an external tank circuit.
field is applied to it, and becomes transparent
negative-resistance oscillator An oscillator that
again when the field is removed. The crystal ma-
consists of a negative-resistance device con-
terial is cut in the form of a letter or numeral and
nected across a tuned circuit. The arrangement
provided with a reflecting backplate for display
oscillates because the negative resistance cancels
readouts in calculators, watches, and various
the positive resistance (losses) of the tuned cir-
electronic devices.
cuit. See, for example, NEGATIVE-RESISTANCE
nematic-crystal display A device in which an elec-
trically controlled film of nematic-crystal material
is used to transmit and interrupt light from a
negative-resistance region In certain devices, a
lamp or from a reflecting mirror, in this way dis-
portion of the voltage-versus-current curve hav-
playing characters in whose shape the film has
ing negative slope (i.e., the current decreases as
been formed.
the voltage increases, or vice versa). Also see N
nematic liquid In a liquid-crystal display (LCD), a
normally clear liquid that becomes opaque in the
negative-resistance repeater A repeater that pro-
presence of an electric field.
duces gain by means of NEGATIVE RESISTANCE
nemo A radio or television program that is picked
up from a location outside the studio. Also called
negative resistor Any device exhibiting NEGATIVE
field pickup or remote.
472 neodymium • neper

neodymium Symbol, Nd. A metallic element of the Frequency
rare-earth group. Atomic number, 60. Atomic
weight, 144.24.
neodymium-YAG laser A laser that uses neo-
dymium and yttrium-aluminum-garnet (YAG)
crystal. It is used in medical applications, such as
surgery and various other jobs where high preci-
sion is required. Generally, it is a low-to-medium-
power laser. Neon Output
neomatachograph An instrument used in psy- bulb
+150 V
chology to measure complex reaction time. Com-
neomatachometer An instrument used in psy-
chology to measure simple reaction time. Com-
neon Symbol, Ne. An inert-gas element. Atomic
neon-bulb oscillator
number, 10. Atomic weight, 20.179. Neon, pre-
sent in trace amounts in the earth™s atmosphere,
is used in some glow tubes, readout devices, and
indicator lamps. neon-bulb sawtooth generator A relatively simple
neon bulb A (usually small) neon-filled gas diode. relaxation oscillator using a neon bulb, capacitor,
It has a characteristic pink glow and is ignited by and resistor. The output is a sawtooth wave,
a firing voltage for the particular unit. Also called whose frequency is determined principally by the
neon glow lamp and neon tube. capacitance and resistance values.
neon-bulb flip-flop A flip-flop circuit (bistable mul- neon-bulb scale-of-two circuit A scale-of-two cir-
tivibrator) using two neon bulbs as the bistable cuit (frequency halver) using neon bulbs as the
components. bistable elements.
neon-bulb gate A gate circuit containing a neon neon-bulb storage A storage (memory) device com-
bulb biased below the firing point. A trigger voltage posed of neon bulbs. A fired bulb (representing a
added to the bias voltage raises the applied voltage bit of stored information) remains fired until
and fires the bulb, producing an output pulse. turned off by an erase signal.
neon-bulb logic Logic circuits composed of neon- neon-bulb stroboscope A stroboscope in which a
bulb gates. neon bulb supplies the light flashes. The circuit is
neon-bulb memory See NEON-BULB STORAGE. essentially that of the neon-bulb oscillator, the
neon-bulb multivibrator A multivibrator using flash rate being continuously variable by an ad-
two neon bulbs as the switching components. justable frequency control.
neon-bulb oscillator A simple relaxation oscillator neon-bulb voltage regulator A simple circuit uti-
consisting essentially of a neon bulb, capacitor, lizing the constant voltage drop across a fired
resistor, and direct-current supply. The frequency neon bulb as a regulated voltage. The usual cir-
of the sawtooth-wave output depends principally cuit configuration is a neon bulb and current-
on the capacitance and resistance values. The limiting resistor in series with a power supply.
maximum operating frequency is limited to about neon-bulb volume indicator A neon-bulb over-
5 kHz by the deionization time of the gas. voltage indicator used in some tape recorders to
neon-bulb overmodulation indicator The appli- show when the volume exceeds a predetermined
cation of a neon-bulb overvoltage indicator level”especially when the volume is high enough
as a monitor for amplitude-modulated radio- to cause an unacceptable amount of distortion.
frequency signals. The bulb flashes each time the neon glow lamp See NEON BULB.
modulation percentage exceeds a predetermined neon lamp See NEON BULB.
value. Also called neon-bulb modulation alarm. neon pilot lamp A neon bulb used as a pilot lamp
neon-bulb overvoltage indicator A relatively sim- operated from the power-line circuit of an elec-
ple circuit in which a neon bulb flashes each time tronic equipment. Also called neon pilot light.
a voltage monitored by the circuit exceeds a pre- neon tube See NEON BULB.
determined value. The flash shows that the por- NEP Abbreviation of NOISE EQUIVALENT POWER.
tion of the voltage presented to the bulb has NEPD Abbreviation of noise equivalent power den-
exceeded the firing potential. sity.
neon-bulb peak indicator See NEON-BULB neper Abbreviation, Np. A Napierian-logarithmic
OVERVOLTAGE INDICATOR. unit expressing a ratio of power levels; Np = loge
(P1/P2)1/2, where P1 and P2 are the power values
neon-bulb ring counter A ring counter composed
of neon-bulb flip-flops. The maximum counting being compared and e is the Napierian logarithm
speed is limited by the deionization time of the neon base, equal to approximately 2.71828. The neper
bulbs to approximately 300 events per second. is related to the decibel (dB), a similar unit based
neper • network analog

on common logarithms, in the following manner: nested loops See NESTING.
1 Np = 8.686 dB; 1 dB = 0.1151 Np. nesting In digital computers and data processing,
neptunium Symbol, Np. A radioactive metallic ele- the inclusion of one or more loops or subroutines
ment produced artificially. Atomic number, 93. inside a larger loop or subroutine. Nested loops,
Atomic weight, 237.05. for example, can be used to assign values to
Nernst effect The appearance of a voltage between double-subscripted variables.
the opposite edges of a metal strip that is con- NET Abbreviation of noise equivalent temperature.
ducting heat longitudinally when the strip is net 1. An effective, useful, or resultant quantity
placed in a magnetic field perpendicular to the (e.g., NET CAPACITANCE). 2. Colloquialism for
plane of the strip. communications network. See NETWORK, 2.
net authentification A password or other special
identification used in a radio network.
net capacitance The resultant capacitance in a
circuit in which capacitances act in combination
with each other.
net component The total value of two or more pas-
sive components of the same sort. See, for exam-
net current The current flowing in a circuit in
which currents aid or oppose each other.
net gain For an amplifier, the amount of gain re-
maining after all losses in the device have been
90° net impedance The impedance of a circuit in
which impedances act in combination with each
net inductance The inductance of a circuit in which
inductances act in combination with each other.
Heated net loss For an amplifier or other system, the alge-
braic sum of gains and losses between two points
in the system.
net power The resultant power observed when
power signals aid or oppose each other in a single
B field
circuit or system.
net radiometer A device for measuring the differ-
ence in intensity between radiation entering the
earth™s surface and radiation leaving it. This is
generally visible light or infrared radiation from
the sun.
Nernst effect net reactance Symbol, Xt. The combined inductive
reactance (XL ) and capacitive reactance (XC) in a
Nernst-Ettinghausen effect In a piezoelectric crys- circuit or device.
tal, the tendency for a temperature gradient to ex- net resistance The resistance of a circuit in which
ist as a result of applied electromagnetic fields. resistances act in combination with each other.
Nernst lamp An incandescent lamp in which the net voltage The resultant voltage at a point where
filament material is a mixture of magnesia and voltages aid or oppose each other.
certain rare oxides (such as yttria). A surround- network 1. A circuit arrangement of electronic
ing current-carrying coil heats the filament, low- components, sometimes redundant in its design
ering its resistance and causing it to glow, after [e.g., resistance-capacitance (RC) network]. 2. A
which it continues to operate on a low current. group of interconnected computers, communica-
nerve center The most essential part of a control tions stations, or other facilities, often organized
system or communication network. for simultaneous operation and data transfer.
nerve current In an animal organism, the small 3. To conduct research or gather information
electrical current that flows along nerve fibers. using a group of interconnected computers,
nervous breakdown The upset of a function in a dig- communications stations, or other facilities.
ital computer (which becomes disabled as a result). network analog A circuit or circuits representing
NESC Abbreviation of National Electrical Safety variables and used to express and solve a mathe-
Code. matical relationship between the variables.
474 network analysis • neutral wire

network analysis The rigorous examination of a neuroelectricity Low-voltage electricity in the ner-
network to determine its properties and perfor- vous system of a human being or animal.
mance. Compare NETWORK SYNTHESIS. neuron A nerve cell in a living organism.
network analyzer An analog or digital circuit for neurosurgery assistance robot An electrome-
simulating and analyzing a network (see NET- chanical device, controlled by a human operator
WORK, 1) by means of measurements and calcu- and assisted by computers, that helps to perform
lations from the model so obtained. simple neurosurgical operations requiring ex-
network assurance The construction and opera- treme precision and steadiness. One procedure
tion of a network in such a manner that failures for which a robot has been used is the drilling of
can be quickly and easily located and corrected. holes in the skull prior to brain surgery.
network calculator An analog or digital device for neutral 1. Having no electric charge; thus, an
determining the component values and perfor- atom is normally neutral because its internal
mance of a given network (see NETWORK, 1). positive charges neutralize its internal negative
network constant The value of a passive compo- charges. 2. Devoid of voltage (e.g., a neutral line).
nent (capacitance, inductance, resistance, etc.) 3. Pertaining to a chemical, especially a solution,
used in a network (see NETWORK, 1). that is neither acidic nor alkaline.
network filter A transducer that passes or rejects neutral bus See NEUTRAL WIRE.
signals, depending on their frequency. neutral circuit 1. A deenergized circuit (i.e., a
network interface unit Abbreviation, NIU. A de- “dead” one). 2. In a teletypewriter system, a cir-
vice, provided to each subscriber, that connects cuit in which current flows in one direction.
telephones, television sets, and personal comput- neutral conductor See NEUTRAL WIRE.
ers to an electrical or fiberoptic cable. Envisioned neutral ground A ground connection to a neutral
as an integral component of the multimedia IN- wire or to the neutral point of a circuit.
FORMATION SUPERHIGHWAY. neutralization The process of balancing out posi-
network provisioning The control of a network by tive feedback in an amplifier to prevent self-
means of computer software, rather than via oscillation. Also see NEUTRALIZING CAPACITOR
manual rearrangement of system devices. and NEUTRALIZING COIL.
network relay 1. A relay that provides protection neutralization indicator A neon bulb or radio-
of the circuits in a network (see NETWORK, 1); a frequency meter used during neutralization of an
circuit breaker. 2. In a communications network amplifier. When the amplifier is properly neutral-
(see NETWORK, 2), the reception and retransmis- ized, the bulb or meter will show zero signal with
sion of a message by a human operator. no input to the amplifier, indicating that the cir-
network synthesis The design and fabrication of a cuit is not oscillating.
network (see NETWORK, 1) by rigorous engineer- neutralize To eliminate positive feedback in a ra-
ing methods to achieve a prescribed performance. dio-frequency amplifier.
network theorems See COMPENSATION THEO- neutralized amplifier An amplifier in which neu-
REM, MAXIMUM POWER TRANSFER THEOREM, tralization has been performed to prevent self-os-
REM, SUPERPOSITION THEOREM, and neutralizing capacitor In a capacitively neutral-
THEVENIN™S THEOREM. ized circuit, a small capacitor that serves as a
network topology The analysis of networks (see coupler of signal energy from the output back
NETWORK, 1) with signal-flow diagrams. Compo- to the input in reverse phase, to cancel self-
nents of the diagram represent signal paths, open oscillation of the circuit.
loops, closed loops, and node points. neutralizing circuit Any component or set of com-
network transfer function A function describing ponents that is used to neutralize a radio-
the overall processing of energy by a network (see frequency amplifier.
NETWORK, 1); it is equal to Vo/Vi, where Vi is the neutralizing coil In an inductively neutralized cir-
input voltage and Vo is the output voltage of the cuit, a small coupling coil that picks up signal en-
network. ergy from the output and applies it in reverse
Neuman™s law A property of mutual inductances. phase to the input, to cancel circuit self-oscillation.
For a given orientation and environment for two neutralizing tool A nonconducting screwdriver-
inductors, the value of the mutual inductance like device for adjusting a neutralizing capacitor
does not change, regardless of the magnitude, or coil. It is usually made of fiber or plastic.
frequency, or phase of the currents in the coils. neutralizing voltage The feedback voltage that can-
That is, mutual inductance is subject only to the cels self-oscillation in the process of neutralization.
physical environment surrounding the coils. neutralizing wand See NEUTRALIZING TOOL.
neuristor A two-terminal semiconductor device neutral line See NEUTRAL WIRE.
that simulates the behavior of a neuron (nerve neutral relay See UNPOLARIZED RELAY.
cell) and allows machines to duplicate some of neutral wire In a polyphase power-transmission
the neurological phenomena observed in the hu- system, the line (wire) that does not carry current
man body. until the system is unbalanced.
neutrodon • nickel“iron

neutrodon See NEUTRODYNE. nibble In computer operations, a four-bit word.
neutrodyne A radio-frequency amplifier that is NICAD Acronym for NICKEL“CADMIUM.
neutralized by feeding energy through a small ca- NiCd Chemical symbol for NICKEL“CADMIUM.
pacitor from a tap on the secondary coil of the Nichrome A nickel-chromium alloy used in the
collector or drain output transformer back to the form of a wire or strip for resistors and heater el-
base or gate. ements.
neutron An uncharged atomic particle having a nickel Symbol, Ni. A metallic element. Atomic
mass approximately equal to that of the proton. number, 28. Atomic weight, 58.69. Nickel is fa-
The neutron is present in the nucleus of every miliar as an alloying metal in some resistance
atom, except that of hydrogen. wires and as the material used in some electron-
neutron age 16.7% of the mean square displace- tube elements.
ment of a neutron as it moves through a specified nickel“cadmium Acronym, NICAD. Chemical
energy range. symbol, NiCd. A mixture used in certain
neutron rest mass See MASS OF NEUTRON AT rechargeable electrochemical cells and batteries.
REST. In recent years, these cells and batteries have
new candle See CANDELA. been largely replaced by nickel“metal-hydride
newton (Sir Isaac Newton.) Symbol N. The SI unit (NiMH) and lithium-based units. These batteries
of force. A force of 1 newton imparts an acceler- must be disposed of in a special way because of
ation of 1 meter per second per second to a the toxic cadmium they contain. Compare
mass of 1 kilogram. The newton is equal to 105 NICKEL“METAL-HYDRIDE.
dynes. nickel“cadmium battery 1. A battery of nickel“
Newton™s laws of motion Three natural laws dis- cadmium cells. 2. Loosely, a nickel“cadmium
covered in 1686 by Sir Isaac Newton. First law: A cell. See also NICKEL“CADMIUM.
body at rest or in motion tends to remain in that nickel-cadmium cell A small, rechargeable, electro-
state, unless it is acted upon by some force. Sec- chemical cell. The anode is cadmium, the cathode
ond law: A body tends to accelerate or decelerate is nickel hydroxide, and the electrolyte is potas-
when it is acted upon by a force, the acceleration sium hydroxide. See also NICKEL“CADMIUM.
or deceleration being directly proportional to the
force and inversely proportional to the mass of ’
the body. Third law: For every action or acting anode
force, there is an equal and opposite reaction or
reacting force.
nexus An interconnection point in a system.
NF Abbreviation of NOISE FIGURE.
nF Abbreviation of NANOFARAD. Potassium
NFET Abbreviation of N-CHANNEL JUNCTION hydroxide
MODULATION. Also abbreviated NBFM.
NFM reception Reception of a signal having NAR-
dard discriminators and ratio detectors can be
used. Slope detection can be achieved with an
amplitude-modulation (AM) receiver by tuning
slightly to one side of the center frequency of the
FM signal.
NFM transmission Transmission of a signal via
nickel-cadmium cell
simple method consists of frequency modulating
the master oscillator of the transmitter at the
modulation frequency. Phase modulation can nickel hydroxide Chemical symbol, NiOH. A com-
also be used. pound used in certain rechargeable electrochemi-
NFPA Abbreviation of National Fire Protection Asso- cal power supplies. Examples are nickel“cadmium
ciation (see NATIONAL ELECTRIC CODE). (NiCd or NICAD) and nickel“metal-hydride (NiMH)
NFQ Abbreviation of night frequency. batteries, used in older notebook computers.
NG 1. Abbreviation of NEGATIVE GLOW. 2. Abbre- nickel“iron Chemical symbol, NiFe. A mixture used
viation of no good, used for marking inoperative for a specialized rechargeable electrochemical cell
or malfunctioning components. in which the active positive plate material consists
nH Abbreviation of NANOHENRY. of nickel hydroxide. The active negative plate mate-
nhp Abbreviation of NOMINAL HORSEPOWER. rial is powdered iron oxide mixed with cadmium,
Ni Symbol for NICKEL. and the electrolyte is potassium hydroxide.
476 nickel-iron battery • noctovision

nickel-iron battery See EDISON BATTERY. nitrocellulose See CELLULOSE NITRATE.
nickel-metal“hydride Chemical symbol, NiMH. A nitrogen Symbol, N. A gaseous element. Atomic
mixture used in certain rechargeable electrochem- number, 7. Atomic weight, 14.007. Nitrogen is
ical cells and batteries. This type of cell or battery the most-abundant component (about 78%) of
is less likely than nickel“cadmium units to develop the Earth™s atmosphere.
battery memory or memory drain, in which the NIU Abbreviation of NETWORK INTERFACE UNIT.
ampere-hour capacity is reduced because of repeated Nixonite A trade name for cellulose acetate, a
partial discharging. In addition, the chemicals in plastic.
NiMH cells and batteries are less toxic than those Nixonoid A trade name for cellulose nitrate, a
in NICADs. Compare NICKEL“CADMIUM. plastic.
nickel“metal-hydride battery 1. A small, NJCC Abbreviation of National Joint Computer Con-
rechargeable, nickel-based electrochemical bat- ference.
tery, similar to the nickel“cadmium (NICAD) type. n layer A semiconductor layer doped to provide
2. Loosely, a nickel“metal-hydride cell. See current carriers that are predominantly elec-
nickel“metal-hydride cell A small, rechargeable, n-level logic 1. A multilevel form of logic, with n
nickel-based electrochemical cell, similar to the different possible states. 2. In a computer, the
nickel“cadmium type. See also NICKEL“METAL- connection of up to n logic gates.

HYDRIDE. NLR 1. Abbreviation of nonlinear resistance. 2. Ab-
nickel-oxide diode A diode fabricated from nickel- breviation of NONLINEAR RESISTOR.

oxide semiconductor material. NLS Abbreviation of NO-LOAD SPEED.
N/m2 Abbreviation of newtons per meter squared
nickel silver An alloy of copper, nickel, and zinc,
sometimes used for making resistance wire. Also (pascals).
Nm2/kg Newton meters squared per kilogram, the
Nicol prism An optical component for producing or SI unit of the gravitational constant.
analyzing plane-polarized light. It consists of two NMAA Abbreviation of National Machine Accoun-
prisms of Iceland spar cemented together. Light tants Association.
entering the device strikes the interface, where NMOS A metal-oxide semiconductor device made
the ordinary ray is totally reflected and the ex- on a p-type substrate whose active carriers, elec-

traordinary ray passes through, both rays being trons, migrate between n-type source and drain
plane-polarized perpendicular to each other. contacts.
NIDA Abbreviation of numerically integrating differ- NMR 1. Abbreviation of NUCLEAR MAGNETIC
ential analyzer. RESONANCE. 2. Abbreviation of NORMAL-
TOR. n-n junction In a semiconductor device, especially
NiFe Chemical symbol for NICKEL“IRON. an integrated circuit, the junction between two
night effect A phenomenon sometimes observed n-type regions having somewhat different proper-
at frequencies below approximately 500 kHz. Di- ties (sometimes designated n1 and n2).
rection-finding signals received between sunset NO Abbreviation of NORMALLY OPEN.
and the following sunrise appear to come from a No Symbol for NOBELIUM.
transmitter that moves slowly back and forth. No. Abbreviation of NUMBER.
night-effect errors In radio direction-finding, in- no-address instruction In digital computer opera-
accurate or uncertain readings resulting from the tions, an instruction requiring no reference to
NIGHT EFFECT. storage or memory for its execution.
night range The distance over which signals from nobelium Symbol, No. A radioactive element pro-
a given transmitter are consistently received after duced artificially. Atomic number, 102. Atomic
sunset. weight, approximately 259 (varies with isotope).
ni junction In a semiconductor device, the junction Nobili™s rings See ELECTRIC RINGS.
between an n-type layer and an intrinsic layer. noble Chemically inert or inactive. For example,
nil 1. Colloquialism for negligible. 2. British ex- noble metals oxidize less rapidly than base met-
pression for zero. Also, nought. 3. Colloquialism als.
for nothing. noble gas An inert rare gas (such as argon, helium,
NiMH Chemical symbol for NICKEL“METAL- krypton, neon, or xenon). It is used in electronic
HYDRIDE. glow devices.
niobium Symbol, Nb. A metallic element chemi- noble metal A comparatively nonreactive metal
cally resembling tantalum. Atomic number, 41. (such as gold, silver, or platinum).
Atomic weight, 92.91. noctovision A television transmission system us-
NIPO Abbreviation of negative input/positive output. ing infrared rays instead of visible light to scan
NIR Abbreviation of NEAR INFRARED. the object. This makes it possible to televise im-
nit In digital-computer operations, a unit of data ages in complete visual darkness (hence, the pre-
equal to 1.44 bits. fix nocto-, meaning “night”).

no-charge machine fault time • noise current

no-charge machine fault time Unproductive com- noise-balancing system A bridge circuit inserted
puter time resulting from errors or a malfunction. between a receiver and antenna for balancing out
nodal point See NODE. interferential signals resulting from nearby
node 1. The terminal point at which two or more power-line leaks or similar causes.
branches of a circuit meet, or a point that is noise bandwidth Abbreviation, NBW. A figure ob-
common to two circuits. 2. In a standing-wave tained by dividing the area under the power-
system, a zero point or minimum point, e.g., output-vs.-frequency curve of a device by the
current node. Compare LOOP, 1. 3. A database power amplitude at the noise frequency of interest.
management system expression defining the noise behind the signal Noise caused by, but ex-
location of information about a record, user, clusive of, a signal.
field, etc. 4. A point at which a satellite crosses noise blanker A device that cuts off one of the inter-
the equator. See also ASCENDING NODE, DE- mediate-frequency stages of a radio receiver during
SCENDING NODE. a noise pulse. The noise blanker is effective against
high-amplitude impulses of short duration.
noise-canceling antenna A specialized receiving
antenna system that uses two elements, one in-
tended for receiving primarily the desired sig-
nal(s) and the other intended for receiving
primarily local human-made noise. The outputs
from the two elements are combined so that the
noise impulses appear out of phase, but of equal
Node Node amplitude. Because one element is located in a
favorable position for reception of desired sig-
nals while the other element is not, the desired
signals do not cancel at the receiver input. As a
result, the signal-to-noise ratio is greatly
node, 2
improved, compared with the use of the signal
antenna alone.
nodules 1. Oxide particles that protrude above the
surface of magnetic tape. 2. In a planar pattern


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