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384 isothermal process • -ize
isothermal process A physical or chemical process
in which there is no temperature change as
other factors vary. Compare ENDOTHERMIC RE-
ACTION and EXOTHERMIC REACTION.
isotope An atom having the same number of protons
as another atom, thereby composing the
same chemical element, but having a different
number of neutrons. Thus, deuterium is an isotope
of hydrogen. Some isotopes are radioactive
[e.g., carbon 14 (an isotope of the more-common
carbon 12)]. The two extra neutrons in carbon 14
make it less stable than carbon 12.
isotropic antenna A theoretically ideal antenna
that transmits and/or receives electromagnetic
fields equally well, and with 100-percent efficiency,
in all directions in three-dimensional free
space.
isotropic radiator A theoretically ideal radiating
element that transmits electromagnetic fields
equally well, and with 100-percent efficiency, in
all directions in three-dimensional free space.
I sup Symbol for suppressor current.
I(t) Symbol for INDICIAL RESPONSE.
ITD Abbreviation for INITIAL TIME DELAY.
item 1. Component. 2. Any one of a number of
similar or identical components, circuits, or systems.
iteration Repeating a series of arithmetic operations
to arrive at a solution to a problem. Computers
are commonly programmed to do this
thousands, millions, or billions of times. Such a
program must include a statement of acceptable
accuracy so that it knows when to leave the iteration
loop.
iterative impedance In a network consisting of
identical, cascaded sections, the input impedance
of a section to which the output impedance
of the preceding section is made equal.
iterative routine A program or subroutine that
provides a solution to a problem by iteration.
iterative transfer constant Symbol, P. A property
of ITERATIVE IMPEDANCE networks. If I i is the
network input current and I o is the network output
current, then P = log e (I o /I i ).
ITU Abbreviation for International Telecommunication
Union.
ITV 1. Abbreviation of INDUSTRIAL TELEVISION.
2. Abbreviation for INTERACTIVE TELEVISION.
I-type semiconductor See INTRINSIC SEMICON-
DUCTOR.
I X Symbol for current in a reactance.
I Y Symbol for current in an admittance.
I Z Symbol for current in an impedance.
-ize A suffix used, with some liberty, to form
verbs from nouns. In electronics, this commonly
refers to procedures or processes (e.g., to AN-
ODIZE, ELECTROCIZE, PLASTICIZE, or TRAN-
SISTORIZE).