18WuD2x

extreme • E zone 273
quantity. 2. The lowest or highest point of the dependent
variable in the range of a function. 3. An
unusual value for a parameter (e.g., temperature
extreme and pressure extreme).
extremely high frequency Abbreviation, EHF. A
frequency near the upper limit of the radio-frequency
spectrum—especially one in the 30- to
300-GHz band.
extremely low frequency 1. Abbreviation, ELF.
Pertaining to a signal or current within the audiofrequency
(AF) range, but not used for audio applications.
2. Electromagnetic emissions from a
cathode-ray tube (CRT), resulting from the currents
in the deflecting coils and/or electron
beam. 3. The 60-Hz electromagnetic field generated
by utility power lines and wiring.
extrinsic base-resistance/collector-capacitance
product Units: seconds, milliseconds, and microseconds.
For a bipolar transistor, the product
R B C C , where R B is the base resistance and C C is
the collector capacitance. This product is a time
constant that determines the high-frequency operating
limit of the transistor.
extrinsic conductance For a material, the conductance
resulting from impurities or such external
factors as environmental conditions.
extrinsic properties For a semiconductor material,
properties resulting from doping (e.g., altered
resistivity or majority/minority carrier differentiation).
Also see EXTRINSIC SEMICONDUCTOR.
extrinsic semiconductor A semiconductor material,
such as germanium or silicon, to which a
controlled amount of a suitable impurity material
has been added to give the semiconductor a desired
resistivity and polarity. Compare INTRINSIC
SEMICONDUCTOR.
extrinsic transconductance Symbol, g m . For a
bipolar transistor, the first derivative of collector
current, with respect to base-emitter voltage. It is
the ratio of a small change in collector current
(dI C ) to the small change in base-emitter voltage
(dV BE ) that produced it, collector voltage being
constant; g m = dI C /dV BE .
extrusion The process of forming a material such
as metal or plastic, by forcing it through dies.
Many pieces of electronic hardware are mass produced
in this manner. Examples are insulating
rods and tubes, metal cans, and metal tubing.
eye-in-hand system In robotics, a scheme that
uses a vision system, servo, and microprocessor
to precisely manipulate an END EFFECTOR, such
as a robot gripper (“hand”). A camera (the “eye”) is
contained in the end effector itself, and is designed
to work at close range (i.e., approximately
one meter down to a fraction of a millimeter).
eyelet connection A connection made by fastening
conductors together with an eyelet or by soldering
leads or pigtails to an eyelet.
eyepiece A small lens system for viewing an oscilloscope
screen through a camera setup.
E Z Symbol for voltage drop across an impedance.
E zone A portion of the earth including most of the
eastern hemisphere. When propagation forecasts
are made, this region is one of three longitude
zones specifie