NUCLEUS --The central part of an atom that
MILLI --A prefix meaning one-thousandth.
is mainly made up of protons and neutrons.
MILLIAMMETER --An ammeter that
It is the part of the atom that has the most
measures current in thousandths of an ampere.
mass.
MOTOR --A machine that converts electrical
NULL --A point or position where a variable-
energy to mechanical energy. It is activated by ac
strength signal is at its minimum value (or
or dc voltage, depending on the design.
zero).
MOTOR-GENERATOR --A motor and a
OHM --The unit of electrical resistance. That
generator with a common shaft used to convert
value of electrical resistance through which a
line voltages to other voltages or frequencies.
constant potential difference of 1 volt across the
resistance will maintain a current flow of 1 ampere
MULTICONDUCTOR --More than one con-
through the resistance.
ductor, as in a cable.
OHM'S LAW --The current in an electrical
MULTIMETER --A single meter combining
circuit is directly proportional to the electromotive
force in the circuit. The most common form of
the law is E = IR, where E is the electromotive
force or voltage across the circuit, I is the current
MULTIPHASE --See POLYPHASE.
flowing in the circuit, and R is the resistance of
the circuit.
MUTUAL INDUCTANCE --A circuit property
existing when the relative position of two
OVERLOAD --A load greater than the rated
inductors causes the magnetic lines of force from
load of an electrical device.
one to link with the turns of the other.
PARAMETERS --In electronics, the design or
NAMP --The Naval Aviation Maintenance
operating characteristics of a circuit or device.
Program.
PERMALLOY --An alloy of nickel and iron
NANOMETER --A unit of length equal to
having an abnormally high magnetic permeability.
10 meter. Formerly millimicron.
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PERMEABILITY --A measure of the ease
NEGATIVE CHARGE --The electrical
with which magnetic lines of force can flow
charge carried by a body that has an excess of
through a material as compared to air.
electrons.
PHASE --The angular relationship between
NEGATIVE FEEDBACK --Feedback in
two alternating currents or voltages when the
which the feedback signal is out of phase with the
voltage or current is plotted as a function of time.
input signal.
When the two are in phase, the angle is zero; both
reach their peak simultaneously. When out of
NEGATIVE TEMPERATURE COEFFI-
phase, one will lead or lag the other; that is, at
CIENT --A characteristic of a semiconductor
the instant when one is at its peak. The other
material, such as silver sulfide, in which resistance
phase will not be at peak value and (depending
to electrical current flow decreases as temperature
on the phase angle) may differ in polarity as well
increases.
as magnitude.
NEUTRON --A particle having the weight of
PHASE DIFFERENCE --The time in elec-
a proton but carrying no electric charge. It is
trical degree by which one wave leads or lags
located in the nucleus of an atom.
another.
NOISE --Any undesired disturbance within
PHOTON (hv) --An elementary quantity of
the useful frequency band; also, that part of the
radiant energy (quantium) whose value is equal
modulation of a received signal (or an electrical
to the product of Plank's constant and the
or electronic signal within a circuit) representing
an undesirable effect of transient conditions.
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