18WuD2x

null frequency • N zone 487
nucleus
Nucleus
Electron
shells
null frequency The frequency at which a frequency-sensitive
circuit, such as a Wien bridge or
twin-tee network, can be balanced.
null meter See BRIDGE DETECTOR.
null method See ZERO METHOD.
null point In a balanced circuit, such as a bridge
or potentiometer, the point of zero output voltage
(or current) or minimum output voltage (or current).
null potentiometer 1. The variable resistor that
constitutes one arm of a four-arm bridge and is
used to balance the bridge. 2. A potentiometric
circuit using the null method to compare one voltage
with another. Also see POTENTIOMETER, 2.
null setting 1. The setting of a bridge circuit or
other null device that balances the circuit. 2. The
electrical zero setting of an electronic voltmeter.
null voltage 1. In a conventional bridge, the output
voltage remaining when the bridge is set for
its best null. 2. For a voltage-sensitive bridge, the
input voltage that will produce zero output voltage.
number The mathematical representation of a
quantity. It is generally used in electronics to denote
coefficients, magnitudes, component values,
frequencies, etc.
number cruncher A computer with great computational
power, but one not necessarily able to
process large amounts of data (such as payroll information).
number system A systematic sequence of numbers
based on a radix and a logical arrangement.
See, for example, BINARY NUMBER SYSTEM and
DECIMAL NUMBER SYSTEM.
numeral A member of a digit set in a number system.
numerical analysis A mathematical approach to
solving problems numerically, including finding
the limits of error in the results.
numerical code A code having a character set restricted
to digits.
numerical control A method of programming
computer-controlled mechanical devices, used in
some early robots. An automated system in which
number sequences fed to a digital computer
cause it to control machines or processes in a
manufacturing operation.
nV Abbreviation of NANOVOLT.
nW Abbreviation of NANOWATT.
nybble A piece of digital information that is larger
than a bit and smaller than a byte. Compare
GULP.
Nylon The trade name for a synthetic fiber-forming
polyamide, useful for electrical insulation.
Nyquist criterion of stability With reference to a
NYQUIST DIAGRAM for a feedback amplifier, the
amplifier is stable if the polar plot of loop amplification
for all frequencies from zero to infinity is a
closed curve that neither passes through nor encloses
the point 1 + j0.
Nyquist diagram A graph of the performance of a
reactive feedback system (such as a degenerative
amplifier) that depicts the variation of amplitude
and phase of the feedback factor with frequency.
The plot is polar and accounts for the real and
imaginary components.
(Imaginary)
jy
Nyquist diagram
Phase
x (Real)
Nyquist noise rule The power dissipated in a resistor
because of thermal noise at a given frequency.
The derivative of frequency, with respect
to power, is equal to the absolute temperature
times the Boltzmann constant.
N zone See N LAYER.