18WuD2x

264 equivalent inductance • equivalent wye
action as the inductance distributed throughout
a circuit.
equivalent input offset current For a differential
amplifier, the difference between currents flowing
into the inverting and noninverting inputs when
the output voltage is zero.
equivalent input offset voltage For a differential
amplifier, the input voltage required to reduce the
output voltage to zero.
equivalent input wideband noise voltage For a
differential amplifier, the ratio V o /G v , where V o is
the root-mean-square (rms) output-noise voltage,
and G v is the direct-current (dc) voltage gain.
equivalent length of antenna 1. The electrical
length of an antenna, as measured in degrees or
wavelengths. 2. The free-space length of an antenna.
3. The length d (in feet) of a quarter-wave
resonant antenna at a specific frequency f (in
megahertz), given by the formula d = 234/f. 4.
The length d (in feet) of a half-wave resonant antenna
at a specific frequency f (in megahertz),
given by the formula d = 468/f.
equivalent length of electric dipole The distance,
measured in a straight line, separating the points
that represent the charge centers of an electric
dipole.
equivalent length of feed line The electrical
length of a feed line as measured in degrees or
wavelengths. Generally, this is equal to 1/v times
the line length in free-space wavelengths, where v
is the VELOCITY FACTOR of the line, expressed
as a fraction between 0 and 1.
equivalent length of magnet The distance separating
the poles of a magnet. In a bar magnet,
these poles are not exactly at the ends. The actual
equivalent length is about 83% of the length of
the bar magnet.
Flux
N
S
Flux
Equivalent
length
equivalent length of magnet
equivalent loudness The actual intensity, in decibels,
of a given sound whose apparent loudness
changes with frequency.
equivalent network A network that can replace a
more-complex network for analysis purposes.
equivalent noise input The value of modulated luminous
flux that, when applied to a photoelectric
device, produces a root-mean-square (rms) output
current equal to the device’s rms noise current.
equivalent-noise-sideband input Abbreviation,
ENSI. A specification for receiver noise characteristics.
Numerically, ENSI = 0.3E s (P n /P s ) 1 ⁄ 2, where
E s is the voltage of an unmodulated radiofrequency
(RF) carrier applied to the receiver, P n
is the resulting noise-output power of the receiver
(measured with an rms meter), and P s is the
noise-output power measured with the RF signal
30% amplitude modulated at 400 Hz with a 400-
Hz bandpass filter inserted between the receiver
output terminals and the meter.
equivalent noise temperature For a component
having resistance, the temperature (degrees absolute)
at which a theoretically perfect resistor
having the resistance of the component would
generate the same noise the component generates
at room temperature.
equivalent optics The analogy between certain optical
lenses and prisms and the electrostatic deflection
of an electron beam. Thus, when the
upper deflecting plate in an electrostatic deflection
system is made negative and the lower plate
is positive, the beam is deflected downward, like
horizontal light rays bent by a prism. When both
plates are made equally negative, the beam converges
to a point, as light rays do when they pass
through a double convex lens. When both plates
are made equally positive, the beam spreads out,
as do light rays passing through a double concave
lens.
equivalent permeability The permeability of a
component made of certain materials, compared
with that of a component having the same reluctance,
shape, and size, but made of different materials.
equivalent reactance The value of a single lumped
reactance that would cause the same action as
the reactance distributed throughout a circuit.
equivalent resistance The value of a single lumped
resistance that would cause the same action as
the resistance distributed throughout a circuit.
equivalent series and parallel circuits Series and
parallel circuits in which current, voltage, phase,
and frequency relationships are identical. Any series
circuit can be transformed into an equivalent
parallel circuit.
equivalent series resistance The equivalent resistance
acting in series with circuit components.
equivalent sine wave A sine wave of the same frequency
and effective voltage as a given wave.
equivalent stopping power For a material in the
path of radioactive particles, the thickness of the
material that produces the same energy loss as
that produced by one centimeter of air.
equivalent time The effective duration of some
phenomenon, such as a pulse.
equivalent volt See ELECTRONVOLT.
equivalent wye In a three-phase system, a wyeconnected
circuit that is equivalent to a given
delta-connected circuit from a standpoint of
impedance and phase. Also see DELTA