. 25
( 42)


motors, and relays. turing integrated circuits, in which there are at
mechanical rectifier A vibrator or commutator least 10, but less than 100, individual gates on
used to change an alternating current into a each chip. Abbreviated MSI.
direct current by selecting and passing only medium-scan television A television (TV) com-
positive or negative half-cycles. Also see munications medium in which the scanning
ELECTROMECHANICAL RECTIFIER. rate is slowed down compared to regular (fast-
mechanical scanner 1. A mechanical device for scan) TV, but is faster than the commonly used
scanning an object or scene and breaking it into slow-scan TV. It provides some conception of
horizontal lines that are converted to signals. 2. A motion, although not as realistic as fast-scan
device that scans the reproducer lamp in a me- TV.
medium tension • meltback transistor

medium tension Medium voltage. A relative term, megohm-farads For a large capacitor, the product
but generally referring to common alternating- of leakage resistance (megohms) and capacitance
current utility voltage (e.g., 117 volts or 234 (farads). Also see MEGOHM-MICROFARADS.
volts). megohmmeter A special ohmmeter for measuring
medium wave Abbreviation, MW. Pertaining to resistances in the megohm range.
wavelengths corresponding to medium frequen- megohm-microfarads For a capacitor, the product
cies (see MEDIUM-FREQUENCY) (i.e., those in of leakage resistance (megohms) and capacitance
the 100- to 1000-meter range). (microfarads). The figure is an expression for the
meg 1. Colloquialism for MEGOHM(s). 2. Colloqui- relative insulation resistance of a capacitor.
alism for MEGABYTE(s). Meissner circuit An oscillator tuned by means of
mega- Abbreviation, M. 1. A prefix meaning mil- LECHER WIRES (parallel-conductor resonant cir-
lion(s), (i.e., 106 or 1,000,000). 2. In digital data cuits). It is used primarily at ultra-high frequen-
applications, a prefix meaning 220 or 1,048,576. cies (UHF).
megabar Abbreviation, Mb. A cgs unit of high pres-
sure. 1 Mb = 106 bars = 1011 pascals. Also see Output
BAR, 1.
megabit A unit of digital data equal to 220
(1,048,576) bits. Also see BIT.
megabyte Abbreviation, M or MB. A unit of digital
data equal to 220 (1,048,576) bytes. Also see BYTE.
megacurie Abbreviation, MCi. A large unit of ra-
dioactivity equal to 3.71 — 106 disintegrations per
second; 1 MCi = 106 curies. Also see CURIE. Drain
megacycle See MEGAHERTZ. tuning
megaelectronvolt Abbreviation, MeV. A large unit
of electrical energy; 1 MeV = 106 eV. Also see
megahertz Abbreviation, MHz. A unit of frequency;
1 MHz = 106 Hz = 1,000,000 Hz.
megampere Abbreviation, MA. A unit of high cur-
rent; 1 MA = 106 A = 1,000,000 A.
megaphone 1. A hand-held microphone/ampli-
+12 V
fier/loudspeaker used to amplify the voice of a
person who must be heard over an appreciable
area. 2. A simple horn for amplifying the voice. Meissner circuit
megarutherford Abbreviation, Mrd. A large unit of
radioactivity equal to 1 trillion (1012) disintegra- Meissner effect In a superconductive material, the
tions per second; 1 Mrd = 106 rd = 1,000,000 rd. abrupt loss of magnetism when the temperature
Also see RUTHERFORD. of the material is reduced to a value below that
megavolt Abbreviation, MV. A unit of extremely required for superconductivity.
high voltage; 1 MV = 106 V = 1,000,000 V. Meissner oscillator See MEISSNER CIRCUIT.
megavolt-ampere Abbreviation, MVA. A unit of ex- meitnerium Symbol, Mt. Also called unnilenium
tremely high reactive power; 1 MVA = 106 VA = (Une). Atomic number, 109. The most common
1,000,000 VA. Also see VOLT-AMPERE. isotope has atomic weight 266. Classified as a
megawatt Abbreviation, MW. A unit of high power; transition metal. It is human-made and not
1 MW = 106 W = 1,000,000 W. Also see WATT. known to occur in nature.
megawatt-hour Abbreviation, MWh. A large unit of mel An expression of apparent or perceived sound
electrical energy or of work; 1 MWh = 106 Wh = pitch. A tone of 1 kHz, at a level of 40 dB, with re-
1,000,000 Wh = 3.6 — 109 joules. Also see WATT- spect to the threshold of hearing, represents 1
HOUR. mel. The perceived pitch depends, to some extent,
megger An instrument containing an internal on the intensity of the sound, as well as on the
high-voltage direct-current power supply, used actual frequency.
for measuring high values of resistance. Compare M electron In certain atoms, one of the electrons
MEGOHMMETER. whose orbits are outside of and nearest to those
meg-mike 1. Colloquialism for MEGOHM-MICRO- of the L electrons.
FARAD(s). 2. Colloquialism for MEGOHM- meltback process The technique of remelting a
FARAD(s). doped semiconductor material and allowing it to
megohm Symbol, M. A unit of high resistance, re- refreeze to form a grown junction.
actance, or impedance; 1 M = 106 ohms = meltback transistor A grown-junction transistor
1,000,000 ohms. produced by the MELTBACK PROCESS.
440 melting point • mercury cell

melting point Abbreviation, mp. The temperature memory protection A hardware device in a multi-
at which a solid starts becoming liquid at a pres- ple programming computer that prevents pro-
sure of one atmosphere. Compare FREEZING grams from being altered by other operating
POINT and MIXTURE MELTING POINT. programs in the installation.
memory 1. The section of a digital computer that memory register In a digital computer, a register
records and holds data until it is necessary. In used in all instruction and data transfers be-
personal computers, the term generally refers to tween the memory and other sections of the ma-
MEMORY, contained in integrated circuits (ICs). memory unit See MEMORY.
Compare STORAGE. 2. See MEMORY DRAIN. mendelevium Symbol, Md. A radioactive element
memory address register In computer storage, a produced artificially. Atomic number, 101.
register in which is stored the address of Atomic weight, 258 (approx.).
operands in other locations. menu In computer operations, a list of commands
memory area A portion of computer memory re- for using various functions of the system.
served for a specific type of data. Also called area. MEP Abbreviation of mean effective pressure.
memory capacity As a function of the number of mercuric iodide Formula, HgI2. A compound
memory locations available, the number of bytes whose crystals are useful at room temperature as
that can be stored. It is usually specified in kilo- detectors in high-resolution gamma-ray spec-
bytes, megabytes, or gigabytes. Also see GIGA- troscopy.
BYTE, KILOBYTE, and MEGABYTE. mercury Symbol, Hg. A metallic element. Atomic
memory cycle 1. The period of execution of a se- number, 80. Atomic weight, 200.59. The only
quence of operations. 2. The complete opera- metal that is liquid at room temperature. It is
tional cycle for inputting data to memory or used extensively in switches, certain high-voltage
retrieving it. rectifiers, high-vacuum pumps, and thermome-
memory dialing In a telephone set, a feature that ters.
allows rapid dialing of stored digits. The simplest mercury arc The arc discharge occurring in mer-
version is the “redial” feature, in which the most cury vapor between solid or liquid (mercury) elec-
recently dialed number is rapidly dialed at the trodes. The discharge emits ultraviolet radiation.
touch of a button. Some sets can store several dif- mercury-arc rectifier A heavy-duty rectifier tube
ferent numbers, usually including area codes, utilizing ionized mercury vapor. The two general
and sometimes country codes as well. types are MERCURY-VAPOR RECTIFIER and
memory drain Also called battery memory. A phe- MERCURY-POOL RECTIFIER.
nomenon occasionally exhibited by nickel“ mercury battery Also called mercuric-oxide bat-
cadmium cells and batteries, in which the useful tery. A set of two or more mercury cells stacked
ampere-hour capacity is reduced even though the one atop the other, electrically connected in se-
unit is not physically damaged. The depth of the ries. The resulting battery has a cylindrical
charge cycle decreases to a fraction of its rated shape. A set of four cells provides approximately
value. The problem can usually be overcome by 5.4 volts under no-load conditions; a battery of
discharging the cell or battery fully, then recharg- seven cells provides 9.5 volts; a battery of nine
ing fully, and repeating the process several times. cells provides 12 volts. See MERCURY CELL.
See also NICKEL“CADMIUM. mercury cadmium telluride Formula HgCdTe.
memory dump In computer operations, to either An alloy used as a semiconductor in certain tran-
print out what is stored in some of or all of the sistors, integrated circuits, and infrared detec-
memory locations or transfer the data from a tors.
bank of memory cells to some external storage mercury cell Also called mercuric-oxide cell. An
medium. electrochemical cell having a button-like shape,
memory effect See MEMORY DRAIN. small enough to fit inside a wristwatch. The
memory guard In a computer, hardware or soft- unit is housed in a steel container and has a
ware that keeps certain memory locations from mercuric-oxide cathode, amalgamated-zinc anode,
being addressed by a program being run. and potassium hydroxide and zinc-oxide elec-
memory location In a computer memory, a place trolyte. The potential difference under no-load
where an information unit (word or character) conditions is 1.35 volts, with a high ratio of
can be stored; the stored information can be re- stored energy per unit mass. The cell has a flat
trieved by appropriate addressing instructions. discharge curve; the voltage remains essentially
memory organization packets In artificial intelli- constant until the charge is almost depleted, and
gence (AI) and expert systems, a method of ar- then the voltage drops rapidly. There has been a
ranging computer memory into general rules or decrease in the use of mercury cells and batteries
statements. The statements are used by software in recent years, because mercury is toxic. Unless
to derive models, forecasts, diagnoses, etc. these cells are discarded in a special way, the
memory power Computer memory efficiency in mercury from them can cause dangerous con-
terms of data processing (cycle) speed. tamination of soil and water.
mercury delay line • meson

mercury delay line A delay line in which delay is globe. Also see TIME ZONE, ZERO MERIDIAN,
obtained by propagating the signal through a and ZONE TIME.
pipe of mercury. mesa A flat-topped, protruding region in a semi-
mercury diffusion pump A vacuum diffusion conductor wafer. The mesa is produced by etch-
pump using mercury vapor. ing the surrounding part of the material. Some
mercury displacement relay A form of switching bipolar transistors are manufactured in this way.
relay in which the electrical contact is made by mesa diffusion A method of manufacturing bipo-
moving mercury. lar transistors. The different semiconductor ma-
mercury-jet switch A multipoint switch using a jet terials are first diffused together. Then part of the
of mercury instead of the conventional wiper arm, resulting wafer is etched away, resulting in a
for high-speed operation and reduced wear. mesa shape.
mercury memory A recirculating memory using a mesa transistor A diffused planar transistor in
mercury delay line. Also see DELAY LINE and which the silicon area around the base has been
DELAY-LINE MEMORY. etched away to reduce collector-to-base capaci-
mercury-pool cathode In certain industrial elec- tance; the base-emitter region remains elevated
tron tubes, such as the ignitron, a cathode elec- like a high plateau (mesa).
trode consisting of a pool of mercury.
mercury-pool rectifier A type of mercury-arc rec-
tifier whose cathode is a pool of mercury. In one
type, the arc is initiated by tilting the tube mo-
mentarily to bring the mercury into contact with Emitter
a third electrode, thus causing a starting current
to flow through the pool. In another type, the ig-
Diffused region
nitron, a starter electrode is in continual contact
with the mercury.
mercury rectifier See MERCURY-POOL RECTI-
mercury relay A relay in which at least one of the
contacts is mercury.
mercury storage See MERCURY MEMORY.
mercury switch A switch consisting essentially of
two or more stiff wire electrodes and a drop of
mercury hermetically sealed in a glass tube. Tilt-
ing the tube causes the mercury to flow toward
mesa transistor
one end, where it immerses the electrodes, pro-
viding a conductive path between them.
mercury-vapor lamp A glow lamp emitting blue- MESFET A form of field-effect transistor combining
green light that causes ionization of mercury va- depletion-mode and enhancement-mode proper-
por by an electric current. ties. A Schottky barrier forms the gate electrode.
mercury-vapor rectifier A tube-type high-voltage mesh 1. A combination of the elements that form a
diode rectifier containing a small amount of mer- closed path in a network. 2. The closed figure
cury that vaporizes and ionizes during tube oper- (such as the delta or star) obtained by connecting
ation. polyphase windings together. 3. A grid, screen, or
mercury-vapor tube 1. See MERCURY-VAPOR similar structure in a vacuum tube.
LAMP. 2. See MERCURY-VAPOR RECTIFIER. mesh equations Equations describing fully the
mercury-wetted reed relay A reed relay in which current and voltage relations in a network of
the reeds are wetted with mercury in a pool by meshes (see MESH, 1).
capillary action. The film of mercury forms a tiny Mesny circuit A push-pull ultra-high-frequency
bridge when the reeds open; when this bridge sep- (UHF) oscillator whose gate or base tank is a pair
arates, a clean, high-speed break occurs without of parallel wires short-circuited by a slider; the
contact bounce. Compare DRY-REED SWITCH. drain or collector tank is a similar pair of wires.
merge 1. In computer operations, to make a single The frequency is varied by moving the sliders
set or file from two or more record sets. 2. In word along the wires.
processing, to create a corrected master record- mesochronous A condition for signals in which
ing from two input media: the original master significant instants pass at identical average
recording and the recording that contains the speeds, such as bits per second.
corrections. meson An unstable nuclear particle first observed
meridian 1. A great circle passing through earth™s in cosmic rays. A meson can be electrically posi-
geographic poles and a given point on the surface tive, negative, or neutral. Its mass lies between
of the earth. 2. A line of longitude on a map or that of the electron and proton.
442 mesotron • meteorograph

mesotron See MESON. metallized capacitor A capacitor in which each
message 1. In communications, a body of infor- face of a dielectric film is metallized to form con-
mation sent from a source (transmitter) to a des- ductive plates.
tination (receiver). 2. Data entered into a metallized-paper capacitor A paper-dielectric ca-
transaction-processing system. pacitor whose plates are metal areas electrode-
message exchange In a digital communications posited on each side of a paper film.
channel, a hardware unit that carries out certain metallized-polycarbonate capacitor A fixed ca-
switching functions that would otherwise have to pacitor in which the dielectric is a polycarbonate
be done by a computer. plastic film, and the plates are metal areas elec-
message switching system A data communica- trodeposited on each face of the film.
tions system having a central computer that re- metallized resistor See METAL-FILM RESISTOR.
ceives messages from remote terminals, stores metal locator An electronic device for locating
them, and transfers them to other terminals as metal deposits, pipes, or wires underground, in
needed. walls, or under floors. It operates via the distur-
metadyne See DC GENERATOR AMPLIFIER. bance that these objects cause to a radio-
metal An elemental material that exhibits several frequency or magnetic field.
familiar properties (such as luster, ductility, mal- metalloid An element that has some of the proper-
leability, good electrical and heat conductivity, ties of a metal. Examples of metalloidal elements
relatively high density, and the ability to emit widely used in electronics are antimony, arsenic,
electrons). Common examples are aluminum, germanium, silicon, and tin.
copper, gold, lead, and silver. Compare METAL- metal master See ORIGINAL MASTER.
LOID and NONMETAL. metal negative See ORIGINAL MASTER.
metal-base transistor A bipolar transistor in metal-oxide resistor A resistor in which the resis-
which the base is a metal film, and the emitter tance material is a film of tin oxide deposited on a
and collector are films of n-type semiconductor substrate.
material. metal-oxide semiconductor field-effect transis-
metal-ceramic construction The building of cer- tor Abbreviation, MOSFET. A field-effect tran-
tain electronic components by bonding ceramic sistor in which the gate electrode is not a pn
parts to metal parts. Also see CERMET. junction (as in the junction field-effect transis-
metal-film resistor A fixed or variable resistor in tor), but a thin metal film insulated from the
which the resistance element is a film of a metal semiconductor channel by a thin oxide film.
alloy deposited on a substrate such as a plastic or Gate-control action is entirely electrostatic. Also
ceramic. called insulated-gate field-effect transistor. Also
metallic binding forces In a crystal, the binding ENHANCEMENT-TYPE MOSFET, and EN-
electrostatic force between cations and electrons. HANCEMENT-TYPE MOSFET.
Also called electron-gas binding forces. metal-oxide varistor A VOLTAGE-DEPENDENT
metallic bonding See BONDING, 1 and METALLIC RESISTOR in which the resistance material is a
BINDING FORCES. metallic oxide, such as zinc oxide.
metallic circuit A circuit, such as a two-wire tele- metal-plate rectifier See METALLIC RECTIFIER.
phone line, in which earth ground is not a part of metal tube A vacuum tube housed in a metal en-
the circuit. Compare GROUND-RETURN CIR- velope for self-shielding and mechanical rugged-
CUIT. ness.
metallic crystal A crystal substance in which pos- metamer A visible-light beam that is identical in
itive ions and free electrons exist; it is, therefore, color (hue), but different in concentration (satu-
a good electrical conductor. ration), with respect to a reference color.
metallic insulator A short-circuited quarter-wave meteor-burst signals Momentary signals, or in-
section of transmission line that acts as an insu- creases in signal strength, resulting from reflec-
lator at the quarter-wavelength frequency. tion of electromagnetic energy from meteor
metallicize To make a circuit fully metallic, as ionization trails. See METEOR SCATTER, 1.
when two wires are used instead of one wire and meteor ionization trail A cloud of ions left in the
a ground connection. (Not to be confused with upper atmosphere as a meteor passes. This cloud
METALLIZE.) tends to reflect radio signals at certain frequen-
metallic rectifier A dry rectifier using a metal disk cies for a short period of time. During a meteor
or plate coated with a material (such as selenium, shower, there could be a sufficient number of
an oxide, or a sulfide). such trails to allow continuous over-the-horizon
metallic tape Recording tape made from metal, communication when other over-the-horizon
rather than from plastic. Noted for its excellent modes are unusable.
audio-reproduction characteristics. meteorograph An instrument for the simultane-
metallize To treat, coat, or plate with a metal. (Not ous measurement of various meteorological phe-
to be confused with METALLICIZE.) nomena such as temperature, humidity, etc.
meteorology • metrology

meteorology The science of the atmosphere, espe- meter-kilogram-second Abbreviation, mks. The
cially the study of weather and climate. (Not to be system of units in which the meter is the stan-
confused with METROLOGY.) dard unit of length, the kilogram is the standard
meteor-scatter propagation The reflection of radio unit of mass, and the second is the standard unit
signals from the ionized trails produced by mete- of time. Compare CENTIMETER-GRAM-SECOND
ors as they pass through the upper atmosphere. and INTERNATIONAL SYSTEM OF UNITS.
This can result in over-the-horizon radio commu- meter multiplier See MULTIPLIER RESISTOR.
nication or reception. A meteor produces a trail meter protector A nonlinear resistor, such as a
that persists for a few tenths of a second up to sev- varistor or semiconductor diode, used to prevent
eral seconds, depending on the size of the meteor, overswing in an electric meter by limiting the cur-
its speed, and the angle at which it enters the at- rent flowing through it.
mosphere. This is not sufficient time for the trans- meter rating The maximum reading on a meter, at
mission of very much information, but during a or below which the accuracy is within a specified
meteor shower, ionization can be almost continu- limit, but above which the error might exceed
ous. Meteor-scatter propagation has been ob- that limit.
served at frequencies considerably above 30 MHz. meter rectifier A light-duty semiconductor diode
meteor-trail reflections Momentary reflection of or bridge circuit, used to change alternating cur-
signals by the ionized trails of meteors passing rent (ac) to direct current (dc) for deflection of a
through a signal path. D™Arsonval-type dc milliammeter or microamme-
meter relay A sensitive relay that is essentially a
Ionized moving-coil meter, whose pointer closes against a
stationary contact mounted at some point along
Meteor the scale.
F layer paths meter resistance Symbol, Rm. The internal resis-
tance of an electric meter. In a simple D™Arsonval
meter, it is the resistance of the movable coil. In
more-complicated meter circuits, it is the resis-
tance of the parallel combination of the coil and
meter scale factor See SCALE FACTOR, 1.
meter sensitivity See VOLTMETER SENSITIVITY.
meter shunt A resistor connected in parallel with
an ammeter, milliammeter, or microammeter to
increase the range of currents that the device can
meter torque See DEFLECTING TORQUE.
meteor-trail reflections
meter-type relay See METER RELAY.
methyl methacrylate resin Also known by the
meter 1. An instrument for measuring and indi- trade name Lucite. A plastic insulating material.
cating the value of a particular quantity. See, for Dielectric constant, 2.8 to 3.3. Dielectric
example, CURRENT METER and VOLTMETER. strength, 20 kV/mm.
2. Abbreviation, m. A unit of linear mea- metre Abbreviation, m. Alternate spelling of meter
sure and of electrical wavelength, equivalent to when used to specify displacement or wave-
1.65076373 — 106 wavelengths (in a vacuum) of the length. See METER, 2.
radiation corresponding to the transition between metric system The decimal system of weights and
the two levels of the krypton-86 atom, and measures based on the meter, kilogram, and sec-
approximately equal to 39.37 inches. 3. To supply ond. Also see CENTIMETER-GRAM-SECOND,
in specific increments or by a governed amount. METER-KILOGRAM-SECOND, and INTERNA-
meter-ampere A unit of transmitted radio signal metric ton Abbreviation, MT. A metric unit of
intensity. Determined by multiplying the antenna weight equal to 1000 kilograms or 1.1023 English
current (in amperes) by the height (in meters) of tons.
the antenna above ground. metric waves British designation for electromag-
meter-candle Abbreviation, mc. A metric unit of il- netic energy having wavelengths ranging from 10
luminance, equivalent to the illumination on a meters down to 1 meter, corresponding to fre-
surface 1 meter from a light source of 1 candle quencies from 30 MHz up to 300 MHz.
power. Compare FOOT-CANDLE and LUX. metrology The science of weights and measures,
meter equivalent The number of meters equal to a including electrical standards and electronic in-
given English measure of length (e.g., the meter struments and measurements. (Not to be con-
equivalent of 3 feet is approximately 0.9144). fused with METEOROLOGY.)
444 metronome • microcomponent

metronome A mechanical or electronic device that Leads
produces audible beats (ticks). It is commonly
used in setting the tempo for music, and for au-
dibly timing certain processes.
MeV Abbreviation of MEGAELECTRONVOLT(s).
mF Abbreviation of MILLIFARAD.
MF 1. Abbreviation of MEDIUM FREQUENCY.
2. Abbreviation of MIDFREQUENCY.
SHIFT KEYING. Thin layer
Mg Symbol for MAGNESIUM. of mica
mg Abbreviation of MILLIGRAM.
MHD power generation See MAGNETOHYDRO-
mica capacitor
mho Obsolete term for the standard unit of electri-
cal conductance. See SIEMENS.
mhp Abbreviation of MILLIHORSEPOWER. uniform base region that is diffused into the
MHz Abbreviation of MEGAHERTZ. wafer before the emitter and collector electrodes
mi Abbreviation of MILE. (Also, m.) are produced by alloying.
MIC Abbreviation of MICROWAVE INTEGRATED microalloy transistor Abbreviation, MAT. A tran-
CIRCUIT. sistor having tiny emitter and collector electrodes
mic Abbreviation of MICROPHONE. that are formed by alloying a thin film of impurity
mica A dielectric mineral of complex silicate compo- material with a collector pit and emitter pit facing
sition, easily separated into numerous thin, trans- each other on opposite surfaces of the semi-
parent sheets. It is widely used as a capacitor conductor wafer. Also see SURFACE-BARRIER
dielectric and high-temperature electrical insula- TRANSISTOR.
tor. Dielectric constant, 2.5 to 7. Dielectric microammeter A usually direct-reading instru-
strength, 50 to 220 kV/mm. Also see MUSCOVITE. ment used to measure current in the microam-
mica capacitor A component that is made by alter- pere range. Also see CURRENT METER.
microampere A small unit of current, equal to 10“6
nately stacking metal sheets and layers of mica,
or by applying silver ink to sheets of mica. The (0.000001) A.
metal sheets are wired together into two meshed microbalance A sensitive electronic weighing de-
sets, forming the two terminals of the capacitor. vice. One type uses one or more servo amplifiers
This type of capacitor is noted for low loss. Voltage for the balancing operation.
microbar A cgs unit of low pressure, equal to 10“6
ratings can be up to several thousand volts if
thick sheets of mica are used. But these capaci- b or 0.1 pascal. Also see BAR, 1 and MILLIBAR.
tors are physically bulky in proportion to their ca- microbarograph A barograph that is sensitive to
pacitance. The main application is in radio small changes in pressure.
receivers and transmitters. Compare CERAMIC microbeam An energy beam (ray) having extremely
PAPER CAPACITOR, PLASTIC-FILM CAPACITOR, microcircuit An extremely small circuit fabricated
TANTALUM CAPACITOR. upon and within a substrate, such as a semicon-
MICR Abbreviation of MAGNETIC INK CHARAC- ductor chip. Also see INTEGRATED CIRCUIT.
micro- 1. A prefix meaning MILLIONTH(S) (i.e., for MICROPROGRAMMING.
10“6). 2. A prefix meaning extremely small (as in microcomponent A tiny component in an elec-
microstructure). Compare MACRO-. tronic circuit. Examples are the resistors, capaci-
microalloy diffused transistor Abbreviation, tors, diodes, and transistors fabricated onto an
MADT. A MICROALLOY TRANSISTOR having a integrated-circuit chip.
microcomputer • micromodule

microcomputer 1. A computer contained within 35-mm size. The film is inserted into a projecting
a single integrated circuit (IC). The simplest device for retrieval of the information.
such devices perform elementary functions and microgalvanometer A highly sensitive GALVA-
are available for a few dollars. More sophisti- NOMETER.
microgauss A magnetic unit equal to 10“6
cated devices control radio receivers and trans-
mitters, television sets, automobiles, aircraft, (0.000001) gauss.
and robots. The most advanced devices can be microgram A metric unit of weight or mass equal
to 10“6 (0.000001) gram.
programmed to provide electrical impulses to
control erratically functioning body organs, microgroove record A phonograph disc with a
move the muscles of paralyzed persons, and very fine groove (200 to 300 per inch), designed
for playback at 331„3 revolutions per minute (rpm).
transcribe speech to writing or vice versa. Com-
microhenry Symbol, µH. A unit of inductance,
pare MICROPROCESSOR. 2. In general, any
equal to 10“6 (0.000001) H.
small computer.
microhm Symbol, µ„¦. A unit of low resistance, re-
microcrystal A crystal that is invisible to the
actance, or impedance, equivalent to 10“6
naked eye.
microcurie A small unit of radioactivity equal to (0.000001) ohm.
3.71 — 104 disintegrations per second or 10“6 microhm-centimeter A unit of low resistivity,
equal to 10“6 (0.000001) ohm-cm. See OHM-
curie. Also see CURIE.
microelectrode 1. An electrode used in MICRO- CENTIMETER and RESISTIVITY.
ELECTROLYSIS. 2. A tiny electrode, especially microhmmeter An instrument for measuring ul-
one of those used in integrated circuits and in tra-low resistance. Such an instrument must
certain biological applications. have a special provision for canceling the effects
microelectrolysis Electrolysis of tiny amounts of of contact and lead resistance.
microinch A unit of linear measure equal to 10-6
material. Also see ELECTROLYSIS, 1.
microelectronic circuit 1. A tiny electronic circuit (0.000001) inch.
other than an INTEGRATED CIRCUIT (i.e., one microinstruction A machine-code instruction
assembled in a small space with small discrete or that controls the operation of a computer directly
integrated components). 2. See MICROCIRCUIT. (i.e., it is a “wired-in” instruction, or one set by
microelectronic device See MICROELECTRONIC DIP switches, independent of programs loaded
CIRCUIT. into the machine).
microelectronics The branch of electronics deal- microknowledge In artificial intelligence (AI), de-
ing with extremely small components and circuits tailed machine knowledge. It includes logic rules,
fabricated on substrates. Also see INTEGRATED computer programs, and data in memory. Com-
microliter A unit of volume, equal to 10“6
microelectrophoresis Electrophoresis of single
particles. (0.000001) liter.
microelectroscope A very sensitive electroscope microlock A special form of phase-locked-loop
used to detect minute quantities of electricity. system, used especially with radar to improve the
microelement A tiny component (capacitor, resis- signal-to-noise ratio.
tor, coil, semiconductor device, or transformer) micromanipulator A machine that permits han-
mounted on a wafer and used in a MICROCIR- dling tiny parts in very small areas. An example of
CUIT. its use is in placing connections close together in
microelement wafer A microwafer on which a mi- microcircuits.
croelement is mounted or deposited. micrometer 1. An instrument for measuring very
microfarad Abbreviation, µF. A unit of capacitance small thicknesses, diameters, etc. 2. Also called
equal to 10-6 (0.000001) F. micron. The SI unit of length, equal to 10“6
(0.000001) meter, or 10“3 (0.001) millimeter.
microfarad meter 1. A dynamometer-type meter
that indicates the value of a capacitor directly in micromho See MICROSIEMENS.
microfarads. Such instruments operate from micromicro- See PICO-.
an alternating-current power line. 2. A direct- micromicrofarad See PICOFARAD.
reading capacitance meter. micromicrohenry See PICOHENRY.
microfiche A method of storing printed informa- micromicron A unit of linear measure equal to
10“12 meter, or 10“6 (0.000001) micrometer.
tion on small film cards. The pages are reduced
and arranged in order from left to right and top to micromillimeter See NANOMETER.
bottom. The card is inserted into a projecting ma- microminiature Pertaining to an extremely small
chine to allow retrieval of the information. The body, component, or circuit; the last adjective in
photographic method is similar to that used in the sequence of those describing size: standard,
MICROFILM. small, midget, miniature, subminiature, and mi-
microfilm A method of storing printed or photo- crominiature.
graphic information. The pages are reduced and micromodule A small, encapsulated circuit, con-
arranged sequentially on a strip of film, usually sisting of smaller components. The components
446 micromodule • microsyn

can be discrete, can consist of integrated circuits, microphonograph A recorder of very low-intensity
or can be a combination of both. The module is sound.
easily removed and replaced by means of a plug- microphonoscope An electronic stethoscope, us-
in socket. ing amplification to enhance the response.
micron See MICROMETER. microphotograph An extremely small photograph,
microphone A transducer that converts sound often of a pattern or mask used in producing
waves, especially speech and music, into electri- transistors and integrated circuits. Not to be con-
cal voltage analogs. fused with photomicrograph, a photograph taken
microphone amplifier A sensitive, low-distortion, through a microscope.
low-noise amplifier used in voice wireless trans- microphotometer A sensitive instrument for mea-
mitters and public address systems. Most ampli- suring small-area light intensity.
fiers of this type have a tailored frequency microphysics The branch of physics concerned
response, passing audio between about 300 Hz with atoms, molecules, and subatomic particles.
nd 3000 Hz, and attenuating audio outside this a micropower Extremely small amounts of power”
range. The range 300 Hz to 3000 Hz is sufficient especially the very low direct-current supply
to convey intelligible voice signals, and also allows power required by some transistors.
for audio-frequency-shift keying (AFSK) and microprocessor The integrated circuit (IC), also
slow-scan television (SSTV) audio input. known as a chip, that coordinates the actions of a

computer and does the calculations. It is located
on the motherboard (sometimes called the logic

+12 V board). These devices get more powerful every
year. Physically, this translates to an increasing
number of digital switching transistors per chip.
The number of digital switches that can be fabri-
cated onto a semiconductor chip of a particular
size is ultimately limited by the structure of mat-
microprogram 1. In computer operations, a rou-
tine of microinstructions that provides a com-

puter a specific function, independent of those
established by programs being run or by the
monitor program. Also see MICROINSTRUCTION.
2. In the direction of a computer, use of a routine
that is stored specifically in the memory, instead
of elsewhere.
microprogramming In the direction of a com-
puter, the use of a routine that is stored specifi-
cally in the memory, instead of elsewhere.
micropulsation Also called micropulse. A pulse of
extremely short duration.
microradiometer A sensitive detector of heat and
infrared radiation, consisting essentially of a
thermopile carried by the moving coil of a gal-
microphone amplifier
microrutherford A unit of radioactivity equal to
one disintegration per second or 10“6 (0.000001)
microphone boom A device used to hang a micro-
rutherford. Also see RUTHERFORD.
phone, with the base out of the way. It is often
microsecond A unit of time measure equal to 10“6
used in radio broadcasting.
(0.000001) second.
microphone hummer See HUMMER.
microsiemens A unit of conductance equal to 10“6
microphone input In an audio amplifier, a jack or
(0.000001) siemens.
other receptacle provided for connection to an ex-
microspectrophotometer An extremely sensitive
ternal microphone. It can also be used with other
spectrophotometer for examining light from tiny
low-level audio apparatus. The jack is connected
to a MICROPHONE AMPLIFIER that provides
microstrip A microwave component that is, in ef-
high gain with minimum internal noise.
fect, a single-wire transmission line operating
microphone oscillator See HUMMER.
above ground.
microphonics Ringing (electrical noises) set up by
microsyn A device that translates rotational posi-
the vibration of a component having loose or mov-
tion into an electrical signal. Similar to a
able elements. For example, ringing noises are
SELSYN. It is used for such purposes as rotator-
generated in some circuit boards when they re-
direction reading.
ceive a physical blow.

microsystems electronics • midrange speaker

microsystems electronics The technology of elec- microwave lens See WAVEGUIDE LENS.
tronic systems using tiny electronic components. microwave mirror A reflector of microwaves.
Also see INTEGRATED CIRCUIT, MICROELEC- microwave oven A device consisting essentially of
TRONIC CIRCUIT, MICROELEMENT, MICRO- a radio-frequency heater using a magnetron
ELEMENT WAFER, and MICROWAFER. oscillator. It produces microwave energy that
microvolt A unit of low voltage, equal to 10“6 causes heating of certain substances via excita-
(0.000001) volt. tion of the molecules.
microvolter An accurate, external attenuator microwave plumbing Collectively, the wave-
(usually for an audio signal generator) providing guides, tees, elbows, and similar fixtures and
stepped and continuously variable output in mi- connections used in microwave setups.
crovolts and millivolts. microwave radio relay The use of microwaves to
microvoltmeter A usually direct-reading instru- relay radio, television, and control signals from
ment used to measure voltages in the microvolt point to point.
range. An input amplifier boosts the test voltage microwave refractometer An instrument using
sufficiently to deflect the indicating meter. microwaves (around 10 GHz) to measure the re-
microvolts per meter A unit of radio-frequency fractive index of the atmosphere.
(RF) field strength. It refers to the RF voltage (in microwave region See MICROWAVE FREQUEN-
microvolts) between an antenna and ground, di- CIES and MICROWAVES.
vided by the height of the antenna (in meters) microwave relay See MICROWAVE RADIO RELAY.
above ground. Compare MILLIVOLTS PER ME- microwave relay system A series of microwave
TER. transmitter-receiver stations for relaying commu-
microvolts per meter per mile A means of ex- nications in several line-of-sight hops.
pressing absolute radio-frequency (RF) field microwaves Radio-frequency electromagnetic en-
strength. Generally, the numerical value is based ergy at wavelengths shorter than about 10 cen-
on the field strength, in MICROVOLTS PER ME- timeters, but longer than the wavelengths of
TER, at a distance of 1 statute mile (5280 feet) infrared energy. See also MICROWAVE FRE-
from the source. QUENCIES.
microwafer A wafer of insulating material, such as microwave spectrum See MICROWAVE FRE-
a ceramic, on which one or more microelements QUENCIES and MICROWAVES.
are mounted and terminals deposited or plated. microwave transistor A transistor whose semi-
microwatt A unit of low power, especially electrical conductor properties and special fabrication en-
power, equal to 10“6 (0.000001) watt. able it to operate at microwave frequencies.
microwattage See MICROPOWER. microwave tube A KLYSTRON, MAGNETRON, or
microwattmeter An instrument for measuring similar tube, used to generate or amplify mi-
power in the microwatt range. Such an instru- crowave radio-frequency signals.
ment obtains its sensitivity from a built-in input midband Abbreviation, MB. The region whose lim-
amplifier. its are immediately above and below a MIDFRE-
microwave See MICROWAVES. QUENCY; the limits are usually specified for a
microwave security system A circuit using mi- particular case.
crowave radio-frequency energy to detect intrud- midband frequency See MIDFREQUENCY.
ers. When an object moves within the field, the midfrequency The center frequency in a specified
intensity of the field changes at one or more band of frequencies.
pickup sensors, triggering an alarm. midget Of reduced size (smaller than small and
microwave acoustics See ACOUSTOELECTRON- larger than miniature).
microwave dish A dish antenna for use at mi- TAL INTERFACE.
crowave frequencies. midpoint voltage The voltage at the terminals of a
microwave early warning Abbreviation, MEW. A cell or battery when it has been discharged
high-power early warning radar system that af- halfway (i.e., when the amount of energy used up
fords large traffic-handling capacity and long is equal to the amount of energy remaining).
range. midrange Pertaining to audio frequencies in the
microwave filter A bandpass filter built into a middle of the human hearing range, where the
waveguide for use at microwave frequencies. ear is the most sensitive. These frequencies lie be-
microwave frequencies The general expression tween the BASS and TREBLE.
for radio frequencies above the ultra-high range, midrange horn A MIDRANGE SPEAKER equipped
that is, 3 GHz or more, but below the frequencies with a flared horn to give the device a unidirec-
of infrared energy. This corresponds to radio tional sound-emission pattern. It is used primar-
wavelengths of 10 centimeters or less. ily in high-power systems and by popular music
microwave integrated circuit Abbreviation, MIC. bands or high-end audio enthusiasts.
An integrated circuit designed for use at mi- midrange speaker A loudspeaker operating most
crowave frequencies. efficiently at frequencies in the middle of the
448 midrange speaker • milliroentgen

audio spectrum. Such a speaker is intermediate milliammeter A usually direct-reading instrument
in performance between a WOOFER and a for measuring current in the milliampere range.
midsection The center section of a multisection fil- milliampere Abbreviation, mA. A unit of current
equal to 10“3 (0.001) ampere.
ter having an odd number of sections; thus, the
second section of a three-section filter. milliampere-hour Abbreviation, mAh. A unit of
low current drain or charging rate, equal to 10-3
migration See ION MIGRATION.
mike 1. See MICROPHONE. 2. See MICROFARAD. (0.001) ampere-hour. Also see AMPERE-HOUR
MIL Abbreviation of military. millibar Abbreviation, mb. A unit of low pressure
mil 1. A small unit of linear measure; 1 mil = 10“3 equal to 10“3 (0.001) bar or = 100 pascals.
(0.001) inch = 0.0254 mm. 2. Thousand, as in n millicurie Abbreviation, mCi. A small unit of ra-
dioactivity equal to 3.71 — 107 disintegrations per
parts per mil.
second, or 10“3 (0.001) curie. Also see CURIE.
mile Abbreviation, m or mi. A large unit of linear
measure, 1 mi = 1.609 km = 5280 feet. millifarad Abbreviation, mF. A seldom-used unit of
capacitance, equal to 10“3 (0.001) farad or 1000
military robot A robot designed and used for the
purpose of executing some task in warfare. The microfarads.
two general types are: human-operated and milligram Abbreviation, mg. A metric unit of
weight equal to 10“3 (0.001) gram.
computer-controlled. An example of a human-
operated military robot is an aircraft that is flown millihenry Abbreviation, mH. A unit of induc-
tance, equal to 10“3 (0.001) henry.
by remote control by a ground-based pilot. The
same robot, or a whole fleet of them, might be millihorsepower Abbreviation, mhp. A unit of
power equal to 10“3 (0.001) horsepower or 0.746
flown by a computer using sophisticated EXPERT
mill A telegraph operator™s typewriter. millilambert Abbreviation, mL. A small unit of
brightness equal to 10“3 (0.001) lambert.
Miller oscillator A crystal oscillator circuit in
which the crystal is connected between the con- milliliter Abbreviation, ml. A metric unit of volume
equal to 10“3 (0.001) liter.
trol electrode and ground. The tuned tank is con-
nected in the output circuit. The internal millimaxwell Abbreviation, mMx. A small unit of
magnetic flux equal to 10“3 (0.001) maxwell or
capacitance of the active device provides feedback
10“11 weber.
coupling. Sometimes called conventional crystal
oscillator. millimeter Abbreviation, mm. A metric unit of lin-
ear measure equal to 10“3 (0.001) meter or
milli- Abbreviation, m. A prefix meaning thou-
0.03937 inch.
sandth(s): 10“3 (0.001).
millimeter equivalent The number of millimeters
equal to a given English measure fraction (e.g.,
the millimeter equivalent of 5„16 inch is 7.937).
millimeter waves Wavelengths between 0.6 and
10 mm (frequencies from 30 to 500 GHz).
millimicro See NANO-.
millimicrofarad See NANOFARAD.
millimicrohenry See NANOHENRY.
millimicron Abbreviation, mm. A unit of wavelength
equal to 10“3 micron or one nanometer (10“9 meter).
millimilliampere See MICROAMPERE.
millimole Abbreviation, mmol. A unit in chemistry
equal to 10“3 (0.001) mole.
milliohm A small unit of resistance, reactance, or
impedance, equal to 10“3 (0.001) ohm.
milliohmmeter An ohmmeter for measuring resis-
tances in the milliohm range.
million electronvolt(s) See MEGAELECTRON-
milliphot A unit of illumination equal to 10“3
(0.001) phot.
millipuffer See PUFFER.
milliradian Abbreviation, mrad. A unit of angular
+12 V measure equal to 10“3 (0.001) radian.
milliroentgen Abbreviation, mr. A small unit of ra-
dioactive dosage; 1 mr = 10“3 (0.001) roentgen =
2.57976 — 10“7 Ci/kg.
Miller oscillator
millirutherford • minor lobe

millirutherford Abbreviation, mrd. A small unit of ameter. It is commonly used with audio equip-
radioactivity equal to 1000 disintegrations per ment.
second; 1 mrd = 10“3 (0.001) rutherford. minifloppy A smaller than standard flexible mag-
millisecond Abbreviation, ms or msec. A small netic disk (floppy).
unit of time equal to 10“3 (0.001) second. minima Points along a curve at which a function
millitorr Abbreviation, mT. An obsolete unit of low reaches a local minimum value. Also see MAXIMA
pressure equal to 10“3 (0.001) torr, or 0.133322 AND MINIMA.
pascal. Also see TORRICELLI.
millivolt Abbreviation, mV. A unit of voltage equal y
to 10“3 (0.001) volt.
millivoltmeter A usually direct-reading instru-
ment for measuring low electric potential. Its
sensitivity is provided by a high-gain amplifier
operated ahead of the indicating meter.
millivolt potentiometer Abbreviation, MVP. A po-
tentiometer-type null instrument for accurately x
measuring small direct-current voltages, such as
those delivered by a thermocouple. Also see PO-
millivolts per meter Abbreviation, mV/m. A unit
of radio-frequency (RF) field strength. It refers to
the RF voltage (in millivolts) developed between Local
an antenna and ground, divided by the height (in minima
meters) of the antenna above ground. Compare
milliwatt Abbreviation, mW. A unit of power equal
to 10“3 (0.001) watt.
milliwattmeter An instrument for measuring minimum Abbreviation, min. The smallest value in
power in milliwatts. Such instruments usually a range or set. Also see MAXIMA AND MINIMA.
obtain their sensitivity from a built-in preampli- minimum detectable signal A signal whose inten-
fier. sity is just higher than the threshold of detection.
Mills cross A radio-telescope antenna, consisting minimum discernible signal Abbreviation, MDS.
of two collinear or phased arrays with a common The lowest input-signal amplitude that will pro-
intersecting lobe. The result is high resolution. duce a discernible output signal in a radio re-
mil-spec security See LEVEL-3 SECURITY. ceiver.
min 1. Abbreviation of MINIMUM. 2. Abbreviation miniscope A very-small-sized, lightweight oscillo-
of MINUTE. scope.
mineral An element or compound that occurs nat- minitrack A system used to track an earth satel-
urally in the earth™s crust. Most minerals are lite, using signals transmitted to the satellite by a
crystalline and many of these have found use in line of ground radio stations.
electronics. Some have been produced artificially. minometer A radioactivity-measuring instrument
mineral oil A natural liquid insulant derived from composed of an ionization chamber and a string
petroleum. Dielectric constant, 2.7 to 8.0. Power galvanometer.
factor, 0.08 to 0.2 percent at 1 kHz. minor beats Secondary or extraneous beats pro-
mineral-oil capacitor An oil capacitor whose pa- duced in a beat-note system, caused by various
per dielectric has been impregnated with mineral sum and difference frequency byproducts of the
oil, which is also the filler. heterodyne process. Compare MAJOR BEATS.
miniature Very small (smaller than midget and minor bend A bend in a rectangular waveguide,
larger than subminiature). made without twisting.
miniature cell An electrochemical cell of very minor cycle See WORD TIME.
small size (e.g., a button cell of the kind used in minor face In a hexagonal quartz crystal, one of
cameras and watches). the three smaller faces. Compare MAJOR FACE.
miniaturization The technology of minimizing the minority carrier The type of charge carrier present
physical size of a circuit or system, while main- in relatively small numbers in a processed semi-
taining its ability to accomplish a given task. conductor material. Electrons are minority carri-
minicalculator A pocket-size electronic calculator. ers in p-type material; holes are minority carriers
minicomputer General term for a computer that is in n-type material. Compare MAJORITY CAR-
more sophisticated than a MICROCOMPUTER, RIER.
but less powerful than a MAINFRAME. minor lobe In a directional antenna system, any
mini connector A jack or plug having two or three lobe other than the main lobe(s). Such a lobe rep-
conductors, and measuring 1„8 (0.125) inch in di- resents reduced sensitivity and/or power gain
450 minor lobe • mixture

relative to the main lobe. Also see MAIN LOBE, misleading precision In electronic calculations
SIDE LOBE. and data recording, greater precision than the in-
minor loop A subordinate path for the circulation struments or conditions justify. Also see SIGNIF-
of information or control signals in an electronic ICANT FIGURES.
system (e.g., minor feedback loop). Compare MA- mismatch The condition resulting from joining two
JOR LOOP. circuits, or connecting a line to a circuit, in which
minute 1. Abbreviation, min. A unit of measure of the impedances are substantially different.
time equal to 60 seconds or 1„60 hour. 2. Also called mismatched impedances Impedances that are
minute of arc. Symbol (˜). A unit of arc measure unequal, and thus do not satisfy the conditions
equal to 1„60 angular degree or 60 seconds. 3. Gen- for maximum power transfer.
eral term meaning “extremely small.” mismatch factor For a load not perfectly matched
MIR Abbreviation of memory-information register. to a driving circuit, the ratio of current flowing in
mirror 1. A device consisting chiefly of a highly the load to the current that would flow in the load
polished or silvered surface that reflects a large if its impedance were perfectly matched to the
part of the radiation (such as light) striking it. output impedance of the driving circuit.
2. Radar-interference material (see CHAFF). 3. To mismatch loss For a load that is mismatched to a
reflect, as by a mirror. source, the ratio P1/P2, where P1 is the power a
mirror galvanometer A galvanometer in which a matched load would absorb from the source, and
mirror is moved by the coil. The mirror either re- P2 is the power actually absorbed by the mis-
flects a spot of light along an external scale, or it matched load.
reflects the scale, which is then read through a mistor A variable-resistance device, used to detect
small telescope. the presence of a magnetic field and to measure
mirror-galvanometer oscillograph See ELEC- magnetic-field strength.
mirror image 1. An image or curve that is exactly mix 1. To produce a beat signal (either the sum or
reversed relative to a straight line or flat plane, the difference frequency) from two input signals.
compared to a reference image or curve. Compare 2. The proportion of powdered iron and other in-
BILATERAL SYMMETRY. 2. For a quarter-wave ert substances in a ferromagnetic transformer
Marconi antenna, the extra quarter-wave element core. Different mixes result in different operating
supplied by the earth. 3. For an antenna at a dis- characteristics.
tance d above a ground plane, an effective an- mixdown A method of combining recorded sound
tenna at an equal distance d below the ground from two or more audio tracks, and recording the
plane. result onto an audio tape or disc. It is used to cre-
ate special audio effects.
mixed-base notation A number system in which
the base (radix) alternates between two digit posi-
tions. Also called mixed radix notation.
mixed calculation A mathematical calculation or
expression in which more than one operation is
mixed modulation Modulation of several kinds co-
Image existing in a system. Thus, a small amount of un-
desired frequency modulation might accompany
amplitude modulation, or vice versa.
mixed number A number having integral (whole)
mirror image, 2 and fractional parts (e.g., 3.14159).
mixer 1. A device, such as a transistor or semicon-
ductor diode, used to mix two input signals and
mirror-reflection echo A false radar echo or set of
deliver an output equal to their difference and/or
echoes, caused by reflection of the radar beam
sum (see MIXING). 2. See AUDIO MIXER. 3. Any
from a plane surface prior to its encountering the
device that combines two or more signals, yield-
target or targets. The beam can also be reflected
ing one output signal whose nature is determined
from one target to another.
by the characteristics of the circuit.
mirror-type meter A meter whose movable coil
mixer noise Electrical noise that occurs in a
carries a small mirror (rather than a pointer) that
reflects a beam of light to produce a spot on a
mixing Combining several signals so that some de-
translucent scale.
sired mixture of the original signals is obtained.
misaligned head In a tape recorder, a record or a
pickup head that is incorrectly oriented, with re-
mixture 1. A combination of two or more signals
spect to the passing tape.
that retain their characteristics”even when they
misfire Failure of a gas tube or mercury-arc tube
interact to produce beat-frequency products. 2. A
to ignite at the correct instant.
mixture • moderator

mntr Abbreviation of MONITOR. (Also, mon.)
Input1 Output
Mo Symbol for MOLYBDENUM.
mobile communications 1. Radio communica-
tions between or among stations on board mov-
ing or stationary land, waterborne, or airborne
vehicles. 2. Radio communications between at
least one fixed station and one or more moving or
stationary land, waterborne, or airborne sta-
Input tions.
2 mobile radio service See MOBILE COMMUNICA-
mobile receiver A radio, television, or other re-
Active ceiver aboard a moving or stationary land, water-
borne, or airborne vehicle.
+ mobile-relay station A fixed station that receives a
signal from a MOBILE STATION and retransmits
it to one or more other mobile stations.
mobile station A station installed and operated
aboard a moving or stationary vehicle. The vehi-
cle might be on land, under water, or in the air.
Input 1 mobile transmitter A radio, television, or other
transmitter aboard a moving or stationary vehi-
cle. The vehicle might be on land, under water, or
in the air.
Input 2 mobility See CARRIER MOBILITY.
mockup See DUMMY, 1.
mod 1. Abbreviation of MODULATOR. 2. Abbrevia-
tion of MODULUS. 3. Abbreviation of MODIFICA-
mixer mode 1. One of the ways a given resonant system
can oscillate. 2. One of the ways that electromag-
diffusion of one substance throughout another, netic energy can be propagated through a device
without a solution or a chemical reaction result- or system. See MODES OF PROPAGATION.
ing. 3. The method via which intelligence is conveyed
mixture melting point Abbreviation, mmp. The in a communications or broadcast signal. See
temperature at which a mixture of solid sub- EMISSION MODE. 4. Resonance of sound waves
stances starts turning into a liquid at 1 atmo- within an acoustic chamber.
sphere of pressure. This melting point depends mode coupling The exchange or interaction of en-
upon the melting points of the substances and ergy between identical modes (see MODE, 1, 2).
their relative concentration in the mixture. Also mode filter A waveguide filter that separates
see MELTING POINT and MIXTURE. waves of different propagation mode, but of the
mks Abbreviation of METER-KILOGRAM-SECOND. same frequency (see MODES OF PROPAGATION).
mL Abbreviation of MILLILAMBERT. model 1. A working or mockup version of a circuit,
ml Abbreviation of MILLILITER. system, or device, illustrative of the final version.
mm Abbreviation of MILLIMETER. 2. A mathematical representation of a process,
mmf Abbreviation of MAGNETOMOTIVE FORCE. device, circuit, or system. Example: the Ruther-
mmol Abbreviation of MILLIMOLE. ford model of the atom.
mmp Abbreviation of MIXTURE MELTING POINT. modeling The creation of an object in three-dimen-
mmv Abbreviation of MONOSTABLE MULTIVI- sional computer graphics.
Mn Symbol for MANGANESE. mode purity In a modulated radio-frequency sig-
mn Symbol for MASS OF NEUTRON AT REST. nal, the condition in which no undesirable types
mnemonic 1. Pertaining to MEMORY or to mem- of modulation exist. For example, a frequency-
ory systems. 2. A memory code or device. modulated signal in which there is zero ampli-
mnemonic code In computer operations, a pro- tude modulation.
gramming code, such as assembly language, moderator A substance, such as graphite or
that, although easily remembered by the pro- heavy water, used to slow neutrons in an atomic
grammer, requires subsequent conversion to ma- reactor. Also see ACCELERATOR, 1 and REAC-
chine language. TOR, 2.
452 modes of propagation • modulation capability

+6 V
modes of propagation The configurations in
which microwave energy can be transmitted
through a WAVEGUIDE.
modes of resonance In a microwave cavity, the
configurations in which resonant oscillation can
exist, depending on the way the cavity is excited. Out
modification 1. Changing the configuration of a
circuit, device, or system, usually to a minor ex-
tent, to tailor its characteristics for a specific pur-
RF in
pose. 2. Changing some aspect of a signal for a
specific purpose (e.g., reducing the emission
bandwidth to allow more signals to fit within a
+6 V
given band of frequencies). 3. In computer opera-
tions, changing program addresses and instruc-
tions by performing logic and arithmetic on them,
as if they were data. Also see PROGRAM MODIFI-
modified alternate mark inversion A signal that
is similar to alternate mark inversion (AMI), but
contains certain differences that are specified by
a rigorous set of standards for the particular sig-
AF in
modifier A data item used to change a computer
program instruction so that it can be used to im-
plement different successive operations. Also see
modulated amplifier
modifier register See INDEX REGISTER.
modify To perform a MODIFICATION to a circuit,
device, system, signal, program address, etc.
moding A fault characterized by oscillation of a modulated-ring pattern See GEAR-WHEEL PAT-
MAGNETRON in undesirable modes. TERN and SPOT-WHEEL PATTERN.
modular technique See BUILDING-BLOCK TECH- modulated stage A transmitter, amplifier, or oscil-
NIQUE. lator in which the signal information is impressed
modulated amplifier A usually high-frequency on the carrier.
amplifier whose output is varied in some way for modulated wave See MODULATED CARRIER.
the purpose of conveying intelligence. Compare modulatee A stage or circuit upon which modula-
MODULATED OSCILLATOR. In the amplitude tion is impressed (e.g., a MODULATED AMPLI-
modulation of an amplifier, there is little or no FIER or a MODULATED OSCILLATOR).
disturbance of the carrier frequency. Also see modulating electrode 1. In an oscilloscope, an
MODULATION. electrode (usually the intensity electrode) to which
modulated beam 1. An electron beam (as in a a signal can be applied to intensity-modulate
cathode-ray tube), whose intensity is varied by a the electron beam. 2. In a cathode-ray tube, the
desired signal. 2. A light beam whose intensity is electrode to which the video signal is applied.
varied for communications or control purposes. modulating signal Intelligence that modulates a
modulated carrier A carrier wave whose ampli- carrier (e.g., binary data in radioteletype, or mu-
tude, frequency, or phase is varied to convey in- sic in broadcasting).
telligence. modulation Combining two signals with the result
modulated continuous wave Abbreviation, mcw. that some aspect of one signal (the carrier) is var-
A high-frequency carrier wave modulated by a ied by and in sympathy with the other (the mod-
continuous, lower-frequency wave, as in MCW ulating signal). Usually, the carrier has a
telegraphy. frequency considerably higher than that of the
modulated CW See MODULATED CONTINUOUS modulating signal.
WAVE. modulation bars A form of television interference
modulated electron beam See MODULATED in which an amplitude-modulated signal causes
BEAM, 1. horizontal bars, alternating light and dark, to ap-
modulated light beam See MODULATED BEAM, pear on the picture screen. The higher the modu-
2. lating frequency, the closer together the bars
modulated oscillator A usually high-frequency appear. In severe cases, the bars completely oblit-
oscillator whose output is varied in some way to erate the picture.
convey intelligence. Compare MODULATED AM- modulation capability The maximum percentage
PLIFIER. Also see MODULATION. of modulation a transmitter will permit before
modulation capability • modulator-demodulator

vice that displays the modulation characteristics
of a signal (e.g., the envelope for amplitude mod-
ulation and single sideband or the frequency-vs.
time function for frequency modulation).
modulation noise See NOISE BEHIND THE SIG-
modulation percentage A measure of the extent
to which a signal is amplitude modulated. It is ex-
multiplied by 100.
modulation ratio For a modulated signal, the quo-
tient Mr/Mi, where Mr is the percentage of radi-
ated-signal modulation, and Mi is the percentage
of current modulation.
modulator A device or circuit for modulating a car-
modulation bars rier.
modulator cell See KERR CELL.
modulator crystal A transparent piezoelectric crys-
tal to which a signal voltage can be applied to mod-
nonlinearity occurs. Also see MODULATION LIN-
ulate a beam of polarized light passing through it.
modulator-demodulator Also called modem. 1. A
modulation characteristic For an amplitude-
device that converts binary data to audio-
modulated wave, the ratio of the instantaneous
frequency-shift-keyed (AFSK) analog signals, and
amplitude of the modulated signal to the instan-
vice-versa. It is commonly used to interface com-
taneous modulating voltage.
puters and terminals with telephone lines and ra-
modulation code In a modulated transmitter, a
dio transceivers. 2. A circuit or device, such as a
system of modulation in which certain signal
variations or pulses represent particular charac-
ters. Examples are ASCII, BAUDOT CODE, and
Data in Data out
modulation coefficient Symbol, m. A figure ex-
pressing the depth (extent) to which a signal is
amplitude-modulated. For a signal in which the
upward modulation is equal to the downward
modulation, m = (Em “ Ec)/Ec, where Ec is the
peak-to-peak voltage of the unmodulated signal,
Amplifier Amplifier
and Em is the peak-to-peak voltage of the modu-
lated signal. For full (100%) modulation, m = 1.
modulation depth See DEPTH OF MODULATION.
modulation distortion 1. In a modulated signal,
envelope distortion introduced by the modulation
process or by the receiver circuit. 2. External
cross modulation (see CROSS MODULATION, 1).
modulation envelope See ENVELOPE, 1.
modulation-envelope distortion Undesirable dis- A/D D/A
tortion in the ENVELOPE of the modulating intel- converter converter
ligence in an amplitude-modulated or single-side-
band signal at the output of a radio transmitter.
modulation factor See MODULATION COEFFI-
modulation frequency Abbreviation, fm. The fre-
quency of a modulating signal.
modulation linearity In a modulated signal, the
degree to which the instantaneous signal ampli-
tude or frequency follows the instantaneous am-
plitude of the modulating signal.
modulation meter See PERCENTAGE-MODULA-
modulation monitor 1. A linear detector with a
pickup coil (or antenna) and headphones for lis-
tening to an amplitude-modulated signal. 2. See
454 modulator-demodulator • molecular conductance

biased diode or diode bridge, that can perform ei- 2. The hollow container used to shape a material,
ther modulation or demodulation. as in 1.
modulator driver An amplifier stage that delivers molded capacitor A capacitor that is molded into
excitation current, voltage, or power to a modula- a protective body of insulating material. Also see
tor stage. MOLD, 1, 2 and MOLDED COMPONENT.
module An assembly containing a complete self- molded ceramic capacitor A ceramic-dielectric
contained circuit (or subcircuit), often miniatur- capacitor enclosed in a molded housing. Also
ized and made for plug-in operation. see MOLD, 1, 2; MOLDED CAPACITOR; and
modulometer Any instrument, such as a percent- MOLDED COMPONENT.
age-modulation meter, used to measure the de- molded coil See MOLDED INDUCTOR.
gree of modulation of a signal. Often, it can also molded component A part (such as a capacitor,
measure other signal characteristics (e.g., carrier coil, or resistor) that is completely enclosed in a
shift, extraneous amplitude modulation, and ex- protective material (such as a plastic) that is
traneous frequency modulation). molded around it. Also see MOLD, 1, 2.
modulo n check In computer operations, a tech- molded electrolytic capacitor A solid-dielectric
nique for verifying the validity of a number used electrolytic capacitor enclosed in a molded hous-
as an operand. The number being so checked is ing. Also see MOLD, 1, 2; MOLDED CAPACI-
divided by another number to provide a remain- TOR; MOLDED COMPONENT; and SOLID-
der (check digit) that goes with the number. After ELECTROLYTIC CAPACITOR.
the number is, for example, transmitted through molded glass capacitor A glassplate-dielectric ca-
some part of a computer system, it is again di- pacitor enclosed in a molded glass housing. Also
vided by the original divisor, and if the remainder see GLASS CAPACITOR; MOLD, 1, 2; MOLDED
is the check digit, the data has retained its in- CAPACITOR; and MOLDED COMPONENT.
tegrity. molded inductor An inductor that is molded into a
modulus 1. Absolute magnitude. Also see ABSO- protective housing of insulating material. Also see
mod. In computer operations, a whole number molded mica capacitor A mica-dielectric capaci-
that indicates the number of states a counter se- tor enclosed in a molded housing. Also see MICA
quences through in each cycle. 3. Abbreviation, CAPACITOR; MOLD, 1, 2; MOLDED CAPACITOR;
mod. A number (constant or coefficient) express- and MOLDED COMPONENT.
ing the degree to which some property is pos- molded mud A molding compound that has infe-
sessed by a material or body (e.g., modulus of rior electrical characteristics. Also see MOLD, 1,
elasticity, shear modulus, and bulk modulus). 4. A 2 and MOLDED COMPONENT.
constant by which a logarithm to one base must molded paper capacitor A paper-dielectric capac-
be multiplied to obtain a logarithm of the same itor enclosed in a molded housing. Also see
number to another base. MOLD, 1, 2; MOLDED CAPACITOR; MOLDED
modulus of elasticity The stress-to-strain ratio in COMPONENT; and PAPER CAPACITOR.
a material under elastic deformation. molded porcelain capacitor A capacitor enclosed
moire In a television or facsimile picture, an effect in a body of molded porcelain. Also see MOLD, 1,
produced by the convergence of straight lines. 2; MOLDED CAPACITOR; MOLDED COMPO-
When the lines are nearly parallel to the scanning NENT; and PORCELAIN.
lines, the converging lines appear irregular. molded resistor A resistor that is molded in a pro-
moisture meter See ELECTRIC HYGROMETER tective housing of insulating material. Also see
mol Abbreviation of MOLE. molded transistor A transistor that is encapsu-
molar conductance See MOLECULAR CONDUC- lated in a protective molding compound, such as
TANCE. epoxy resin. Also see MOLD, 1, 2 and MOLDED
molar polarization Any molecule in an electric COMPONENT.
field undergoes a small displacement of the posi- mole Abbreviation, mol. 1. The amount of sub-
tive and negative electrical centers. This results stance in a system containing as many specified
in an electric dipole. entities (atoms, molecules, ions, subatomic parti-
molar solution A solution, such as an electrolyte, cles, or groups of such particles) as there are
containing 1 mol of solute per liter of solvent. atoms in 12 grams of carbon 12. 2. It is also
Compare NORMAL SOLUTION. called the Avogadro constant. A unit of quantity
in chemistry, equal to approximately 6.022 —
mold 1. To form matter into a desired shape, as by
pouring liquefied material into a container or liq-
uefying the material in the container, then allow- molectronics See MOLECULAR ELECTRONICS.
ing the liquid material to solidify. In hot molding, molecular circuit See MONOLITHIC INTE-
the material is melted in the container and then GRATED CIRCUIT.
cooled to hardness; in cold molding, the material molecular conductance For a solution, such as
is shaped without heat and it solidifies with time. an electrolyte, the product of specific conductivity
molecular conductance • monitor system

and the volume (in liters) of a solution that con- monaural 1. Pertaining to an audio system having
tains 1 gram molecule of the solute. Also see one channel. 2. Pertaining to hearing with one
SOLUTE; SOLUTION, 1; and SOLVENT, 1, 2. ear, as opposed to BINAURAL.
molecular conductivity See MOLECULAR CON- monaural recorder A single-track recorder, as op-
DUCTANCE. posed to a stereophonic recorder.
molecular electronics The technique of process- Monel metal An alloy of nickel (67%), copper
ing a single block of material so that separate ar- (28%), iron, manganese, and other metals (5%).
eas perform the functions of different electronic Its resistivity is approximately 42 microhm-
components. The entire block constitutes a cir- centimeters at 20°C.
cuit (e.g., a MONOLITHIC INTEGRATED CIR- monimatch An amateur version of the reflected-
CUIT). power meter and SWR meter.
molecular magnets According to the molecular
theory of magnetism, the elemental magnets
formed by individual molecules.
molecular theory of magnetism Each molecule in
a piece of magnetic metal is itself a magnet (pos- RF
sessing a north and a south pole). These tiny output
magnets are thought to be normally oriented at
random, but when the material is magnetized by
an external force, they align themselves with each
molecular weight Abbreviation, mol wt. In a
molecule of a substance, the sum of the atomic
weights of the constituent atoms.
molecule The basic particle of a compound; each
molecule usually contains two or more atoms. moniscope A special cathode-ray tube that pro-
For example, the formula AgNO3 represents silver duces a stationary picture for testing television
nitrate, each molecule of which contains one equipment. Its name is a contraction of monitor
atom of silver (Ag), one atom of nitrogen (N), and and scope.
three atoms of oxygen (O). monitor 1. A device that allows the sampling of a
moletronics See MOLECULAR ELECTRONICS. signal or quantity. Examples: line-voltage monitor,
mol wt Abbreviation of MOLECULAR WEIGHT. television monitor, and modulation monitor. 2. A
molybdenum Symbol, Mo. A metallic element. cathode-ray-tube (CRT) computer display.
Atomic number, 42. Atomic weight, 95.94. It is monitor head A separate playback head included
used in the grids and plates of certain vacuum in some tape recorders for listening to the tape as
tubes. it is being recorded.
moment The tendency to produce motion around monitoring The act, process, or technique of ob-
a point, as by torque, or the product of a quantity serving an action while it is in progress or check-
and the distance to a point. The moment of force ing a quantity while it is varying. Examples:
is expressed as the product Fd, where F is force carrier monitoring, modulation monitoring, and
and d is distance. line-voltage monitoring.
momentary-contact switch A switch that main- monitoring amplifier An auxiliary amplifier used
tains contact only while it is held down. Such a in monitoring an audio-frequency system.
device is usually a pushbutton switch, although it monitoring antenna A usually small pickup an-
might be a toggle switch, a slide switch, or a lever tenna used with a signal monitor or monitoring
switch. receiver.
momentary switching Switching of short dura- monitoring key In a telephone system, a device
tion, often characterized by a quick make and used to listen to a two-way conversation.
break immediately following activation of the monitoring receiver A radio or television receiver
switch. Compare DWELL SWITCHING. used specifically to monitor a transmission di-
moment of inertia For a torque motor, the inertia rectly.
of the armature around the axis of rotation. Also monitoring station In a security system, a central
see MOMENT. control location from which personnel can ob-
mon 1. Abbreviation of MONITOR. 2. Abbreviation serve the input from sensors, cameras, and other
of MONAURAL. devices at remote locations throughout the se-
monatomic 1. Pertaining to a molecule with only cured area.
one atom. 2. Pertaining to a molecule with only monitor system A computer program usually
one replaceable atom or radical. stored in the read-only memory (ROM) supplied
monatomic molecule A molecule having a single by the hardware vendor. It controls the imple-
atom (e.g., argon, helium, and neon). Compare mentation of programs written by the user, and
DIATOMIC MOLECULE. the operation of peripherals associated with
456 monitor system • monovalent

program runs and inputting or outputting data to monopole antenna See QUARTER-WAVE MONO-
or from memory. Also called executive program. POLE.
monkey chatter The characteristic sound of a sin- monopulse In radar and electronic-navigation op-
gle-sideband (SSB) signal when the receiver is erations, using one pulse to determine azimuth
mistuned, or when the receiver is set for the and elevation simultaneously.
wrong sideband. monorange speaker A loudspeaker that repro-
monk™s cloth A coarse drapery fabric sometimes duces most of the full audio range. Also called ex-
used to soundproof the walls and ceiling of a ra- tended range speaker. Compare TWEETER and
dio studio or recording booth. WOOFER.
mono See MONAURAL. monostable Having one stable state.
mono- Prefix meaning single. monostable blocking oscillator Abbreviation,
monobrid circuit An integrated circuit in which MBO. A blocking oscillator that behaves some-
either several monolithic IC chips are intercon- what like a one-shot multivibrator. The oscillator
nected to form a larger, single-package circuit, or delivers a single output pulse each time it re-
monolithic IC chips are interwired with thin-film ceives an input (trigger) pulse.
components into a single-package circuit. The monostable multivibrator A multivibrator that
name is a contraction of monolithic hybrid. delivers one output pulse for each input (trigger)
monochromatic 1. Being of one color (hue) in na- pulse. Also called one-shot circuit and single-shot

ture. 2. Being of a single wavelength in nature multivibrator. Compare ASTABLE MULTIVIBRA-
(pertaining to radiation of any kind). 3. Pertaining TOR and BISTABLE MULTIVIBRATOR.

to black-and-white television.
monochromaticity Consisting of one color of visi-
+5 V
ble light. The brightness can vary from black to
monochromatic power density At a given tem-
perature, the energy radiated per square centime-
ter of blackbody surface per second per unit
wavelength range. Also see BLACKBODY and

monochromatic sensitivity Sensitivity to light of Input
one color only.
monochrome television Black-and-white televi-
monoclinic crystal A crystal having three axes of
unequal length; two of them intersect obliquely
and are perpendicular to the third [e.g., the type
of crystal found in one form of sulfur (monoclinic
sulfur)]. Output
monocrystalline material See SINGLE-CRYSTAL
monode A one-element device, such as a filament-
type lamp, thermistor, voltage-dependent resis-
tor, barretter, etc.
monogroove stereo A method of making a stereo-
phonic phonograph disc in which both channels
’5 V
are recorded as a single groove.
monolayer A thin film having a thickness of one
monostable multivibrator
monolithic integrated circuit An integrated cir-
cuit (IC) formed in a single block or wafer of semi- monostatic reflectivity The property whereby, for
conductor material. The name is derived from the certain reflectors (such as a tricorner reflector),
Greek monolithos (“one stone”). Compare HY- all incident rays are reflected in exactly the oppo-
BRID INTEGRATED CIRCUIT and THIN-FILM IN- site direction from which they arrive.
TEGRATED CIRCUIT. monotone A sound or series of sounds having a
monometallic Containing or using only one metal. single, constant pitch (frequency).
monomolecular film See MONOLAYER. monotonicity In a digital-to-analog converter, a
monophonic recorder See SINGLETRACK RE- condition where the output either remains the
CORDER. same or increases for any single increase in the
monophonic system A single-channel sound sys- input code.
tem. Compare STEREO SYSTEM. monovalent See UNIVALENT.

Monte Carlo method • motorboating filter

Monte Carlo method 1. The use of statistical sam- itance might be variable by changing the applied
pling in the approximate solution of an engineer- voltage at the metal gate electrode.
ing problem. 2. In computer operations, the MOSFET Abbreviation of METAL-OXIDE-
construction of mathematical models from ran- SEMICONDUCTOR FIELD-EFFECT TRANSISTOR.
domly selected components taken from represen- MOSROM Abbreviation of metal-oxide-semiconduc-
tative statistical populations. tor read-only memory (see READ-ONLY MEM-
Moog synthesizer An electronic device that can be ORY).
made to simulate virtually any sound, including MOST Abbreviation of metal-oxide-semiconductor
that of musical instruments and the human transistor.
voice, through the use of several audio oscilla- most significant character Abbreviation, MSC. In
tors, whose output can be controlled to produce positional number representation, the leftmost
tones of various harmonic content, duration, at- character in a significant group, such as a word.
tack, and decay periods. most significant digit Abbreviation, MSD. In a
moonbounce Also called earth-moon-earth (EME). number, the leftmost digit that is not zero (zero
Radio communication, usually at very-high fre- being insignificant in this context).
quencies (VHF) or ultra-high frequencies (UHF), mother 1. A term or prefix referring to a compo-
in which the moon is used as a passive reflector. nent that supports (or appears to support) other
This is a popular mode among some amateur ra- similar components (e.g., MOTHERBOARD). 2. A
dio operators. term referring to the source from which samples
or components are derived (e.g., MOTHER CRYS-
TAL). 3. A mold that has been electroformed from
a master phonograph disc.
motherboard In a computer or data-processing
device, the circuit board on which most of the
main circuitry is mounted.
Earth mother crystal A natural quartz crystal from
which is produced the piezoelectric plates and
other components used in electronics.
motion detector A device for sensing the move-
ment or stopping of a body, such as a rotating
shaft. Various sensors are used in different de-
moon bounce
tectors: magnetic, photoelectric, capacitive, etc.
motion frequency The natural frequency (espe-
cially that of oscillation) of a servo.
Motion Picture Experts Group Abbreviation,
MPEG. A data-compression standard used for
morphological electronics See MOLECULAR
animated digital video. It is useful in computer
videoconferencing and telecommuting, and for
Morse 1. See MORSE CODE. 2. Telegraphy (wire or
the development of multimedia presentations.
radio). 3. To signal by means of the Morse code.
motion-picture pickup In television operations, a
Morse code Either of two similar binary codes
camera (and the technique for using it) for pick-
used in radio and wire telegraphy. It uses short
ing up scenes directly from motion-picture film.
pulses (dots or dits) and long pulses (dashes or
motion sensor In security systems, a set of de-
dahs) to represent letters of the alphabet, numer-
vices that produces an output signal whenever
als, and punctuation marks. It usually refers to
anything moves within a certain area. Such
the CONTINENTAL CODE, but occasionally it
equipment might use infrared, ultrasound,
refers to the AMERICAN MORSE CODE.
microwaves, capacitive effects, thermal sensors,
MOS Abbreviation of metal-oxide-semiconductor.
air-current detectors, sound detectors, video
mosaic 1. See PHOTOMOSAIC. 2. The pattern of
cameras, or a combination of these.
tiny photoelectric particles in a television cam-
motor 1. A machine for converting electrical en-
era tube that convert the image into electric
ergy into mechanical energy. 2. The driving
mechanism of a loudspeaker.
mosaic crystal A form of imperfect crystal. The de-
motorboard The basic mechanism of a tape
fects have certain properties, one of which is to
recorder, embodying motor, flywheel, capstan,
cause additional energy levels in semiconductor
rollers, etc., assembled on a board or panel.
materials manufactured from such crystals.
motorboating A repetitive, low-frequency popping


. 25
( 42)