18WuD2x

medium tension • meltback transistor 439
medium tension Medium voltage. A relative term,
but generally referring to common alternatingcurrent
utility voltage (e.g., 117 volts or 234
volts).
medium wave Abbreviation, MW. Pertaining to
wavelengths corresponding to medium frequencies
(see MEDIUM-FREQUENCY) (i.e., those in
the 100- to 1000-meter range).
meg 1. Colloquialism for MEGOHM(s). 2. Colloquialism
for MEGABYTE(s).
mega- Abbreviation, M. 1. A prefix meaning million(s),
(i.e., 10 6 or 1,000,000). 2. In digital data
applications, a prefix meaning 2 20 or 1,048,576.
megabar Abbreviation, Mb. A cgs unit of high pressure.
1 Mb = 10 6 bars = 10 11 pascals. Also see
BAR, 1.
megabit A unit of digital data equal to 2 20
(1,048,576) bits. Also see BIT.
megabyte Abbreviation, M or MB. A unit of digital
data equal to 2 20 (1,048,576) bytes. Also see BYTE.
megacurie Abbreviation, MCi. A large unit of radioactivity
equal to 3.71 × 10 6 disintegrations per
second; 1 MCi = 10 6 curies. Also see CURIE.
megacycle See MEGAHERTZ.
megaelectronvolt Abbreviation, MeV. A large unit
of electrical energy; 1 MeV = 10 6 eV. Also see
ELECTRONVOLT.
megahertz Abbreviation, MHz. A unit of frequency;
1 MHz = 10 6 Hz = 1,000,000 Hz.
megampere Abbreviation, MA. A unit of high current;
1 MA = 10 6 A = 1,000,000 A.
megaphone 1. A hand-held microphone/amplifier/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.
megarutherford Abbreviation, Mrd. A large unit of
radioactivity equal to 1 trillion (10 12 ) disintegrations
per second; 1 Mrd = 10 6 rd = 1,000,000 rd.
Also see RUTHERFORD.
megavolt Abbreviation, MV. A unit of extremely
high voltage; 1 MV = 10 6 V = 1,000,000 V.
megavolt-ampere Abbreviation, MVA. A unit of extremely
high reactive power; 1 MVA = 10 6 VA =
1,000,000 VA. Also see VOLT-AMPERE.
megawatt Abbreviation, MW. A unit of high power;
1 MW = 10 6 W = 1,000,000 W. Also see WATT.
megawatt-hour Abbreviation, MWh. A large unit of
electrical energy or of work; 1 MWh = 10 6 Wh =
1,000,000 Wh = 3.6 × 10 9 joules. Also see WATT-
HOUR.
megger An instrument containing an internal
high-voltage direct-current power supply, used
for measuring high values of resistance. Compare
MEGOHMMETER.
meg-mike 1. Colloquialism for MEGOHM-MICRO-
FARAD(s). 2. Colloquialism for MEGOHM-
FARAD(s).
megohm Symbol, M. A unit of high resistance, reactance,
or impedance; 1 M = 10 6 ohms =
1,000,000 ohms.
megohm-farads For a large capacitor, the product
of leakage resistance (megohms) and capacitance
(farads). Also see MEGOHM-MICROFARADS.
megohmmeter A special ohmmeter for measuring
resistances in the megohm range.
megohm-microfarads For a capacitor, the product
of leakage resistance (megohms) and capacitance
(microfarads). The figure is an expression for the
relative insulation resistance of a capacitor.
Meissner circuit An oscillator tuned by means of
LECHER WIRES (parallel-conductor resonant circuits).
It is used primarily at ultra-high frequencies
(UHF).
Gate
tuning
Meissner circuit
Drain
tuning
Output
+12 V
Meissner effect In a superconductive material, the
abrupt loss of magnetism when the temperature
of the material is reduced to a value below that
required for superconductivity.
Meissner oscillator See MEISSNER CIRCUIT.
meitnerium Symbol, Mt. Also called unnilenium
(Une). Atomic number, 109. The most common
isotope has atomic weight 266. Classified as a
transition metal. It is human-made and not
known to occur in nature.
mel An expression of apparent or perceived sound
pitch. A tone of 1 kHz, at a level of 40 dB, with respect
to the threshold of hearing, represents 1
mel. The perceived pitch depends, to some extent,
on the intensity of the sound, as well as on the
actual frequency.
M electron In certain atoms, one of the electrons
whose orbits are outside of and nearest to those
of the L electrons.
meltback process The technique of remelting a
doped semiconductor material and allowing it to
refreeze to form a grown junction.
meltback transistor A grown-junction transistor
produced by the MELTBACK PROCESS.