18WuD2x

444 metronome • microcomponent
metronome A mechanical or electronic device that
produces audible beats (ticks). It is commonly
used in setting the tempo for music, and for audibly
timing certain processes.
MeV Abbreviation of MEGAELECTRONVOLT(s).
MEW Abbreviation of MICROWAVE EARLY WARN-
ING.
mF Abbreviation of MILLIFARAD.
MF 1. Abbreviation of MEDIUM FREQUENCY.
2. Abbreviation of MIDFREQUENCY.
MFD Abbreviation of MAGNETOFLUID DYNAMICS
(see MAGNETOHYDRODYNAMICS).
MFSK Abbreviation of MULTIPLE FREQUENCY-
SHIFT KEYING.
Mg Symbol for MAGNESIUM.
mg Abbreviation of MILLIGRAM.
MGD Abbreviation of MAGNETOGASDYNAMICS
(see MAGNETOHYDRODYNAMICS).
MHD Abbreviation of MAGNETOHYDRODYNAM-
ICS.
MHD generator See MAGNETOHYDRODYNAMIC
GENERATOR.
MHD gyroscope See MAGNETOHYDRODYNAMIC
GYROSCOPE.
MHD power generation See MAGNETOHYDRO-
DYNAMIC GENERATOR.
mho Obsolete term for the standard unit of electrical
conductance. See SIEMENS.
mhp Abbreviation of MILLIHORSEPOWER.
MHz Abbreviation of MEGAHERTZ.
mi Abbreviation of MILE. (Also, m.)
MIC Abbreviation of MICROWAVE INTEGRATED
CIRCUIT.
mic Abbreviation of MICROPHONE.
mica A dielectric mineral of complex silicate composition,
easily separated into numerous thin, transparent
sheets. It is widely used as a capacitor
dielectric and high-temperature electrical insulator.
Dielectric constant, 2.5 to 7. Dielectric
strength, 50 to 220 kV/mm. Also see MUSCOVITE.
mica capacitor A component that is made by alternately
stacking metal sheets and layers of mica,
or by applying silver ink to sheets of mica. The
metal sheets are wired together into two meshed
sets, forming the two terminals of the capacitor.
This type of capacitor is noted for low loss. Voltage
ratings can be up to several thousand volts if
thick sheets of mica are used. But these capacitors
are physically bulky in proportion to their capacitance.
The main application is in radio
receivers and transmitters. Compare CERAMIC
CAPACITOR, ELECTROLYTIC CAPACITOR,
PAPER CAPACITOR, PLASTIC-FILM CAPACITOR,
TANTALUM CAPACITOR.
MICR Abbreviation of MAGNETIC INK CHARAC-
TER RECOGNITION.
micro- 1. A prefix meaning MILLIONTH(S) (i.e.,
10 –6 ). 2. A prefix meaning extremely small (as in
microstructure). Compare MACRO-.
microalloy diffused transistor Abbreviation,
MADT. A MICROALLOY TRANSISTOR having a
Coating
Leads
Metal
electrodes
mica capacitor
Thin layer
of mica
uniform base region that is diffused into the
wafer before the emitter and collector electrodes
are produced by alloying.
microalloy transistor Abbreviation, MAT. A transistor
having tiny emitter and collector electrodes
that are formed by alloying a thin film of impurity
material with a collector pit and emitter pit facing
each other on opposite surfaces of the semiconductor
wafer. Also see SURFACE-BARRIER
TRANSISTOR.
microammeter A usually direct-reading instrument
used to measure current in the microampere
range. Also see CURRENT METER.
microampere A small unit of current, equal to 10 –6
(0.000001) A.
microbalance A sensitive electronic weighing device.
One type uses one or more servo amplifiers
for the balancing operation.
microbar A cgs unit of low pressure, equal to 10 –6
b or 0.1 pascal. Also see BAR, 1 and MILLIBAR.
microbarograph A barograph that is sensitive to
small changes in pressure.
microbeam An energy beam (ray) having extremely
small cross section.
microcircuit An extremely small circuit fabricated
upon and within a substrate, such as a semiconductor
chip. Also see INTEGRATED CIRCUIT.
microcode 1. See MICROINSTRUCTION. 2. A code
for MICROPROGRAMMING.
microcomponent A tiny component in an electronic
circuit. Examples are the resistors, capacitors,
diodes, and transistors fabricated onto an
integrated-circuit chip.