18WuD2x

536 pitch of winding • plasma diode
pitch of winding In a coil, the distance from the
center of one turn to the center of the adjacent
turn in a single layer of winding.
PIV Abbreviation of PEAK INVERSE VOLTAGE.
pivot The sometimes jeweled, stationary member
of the bearing in an analog meter movement.
pi-wound choke A choke coil consisting of several
series-connected sections, mounted on a single
core and separated to reduce internal capacitance.
pix Abbreviation of PICTURE.
pixel Contraction of picture element. The smallest
bit of data in a video image. Also called pel. The
smaller the size of the pixels in an image, the
greater the resolution for a given image area.
pixel aspect ratio In a video image, the ratio of
PIXEL height to pixel width.
pix tube See PICTURE TUBE.
PL Abbreviation for PRIVATE LINE.
place effect An apparent change in the perceived
pitch of a sound, caused by variations in the way
the waves interact inside the human ear.
planar diffusion In the production of a semiconductor
device, the diffusion of all the elements
into one face of a wafer. Consequently, connections
to the elements all lie in one plane. Also see
EPITAXIAL PLANAR TRANSISTOR and PLANAR
TRANSISTOR.
planar diode A semiconductor diode, having a pn
junction that lies entirely within a single plane.
planar epitaxial passivated diode A junction
diode that, like the planar epitaxial transistor,
has been manufactured by planar diffusion, then
passivated to protect the junction. Also see EPI-
TAXIAL GROWTH, EPITAXY, PASSIVATION, and
PLANAR DIFFUSION.
PL/1 A computer programming language that is a
hybrid of scientific and commercial types (like AL-
GOL and COBOL), the combined features being
powerful problem-solving and mass-datahandling
abilities.
planar epitaxial passivated transistor A planar
epitaxial transistor that has been passivated to
protect the exposed junctions. Also see EPITAX-
IAL PLANAR TRANSISTOR, PLANAR TRANSIS-
TOR, EPITAXIAL TRANSISTOR, PASSIVATION,
and PLANAR TRANSISTOR.
planar transistor A transistor in which the emitter,
base, and collector elements terminate on the
same face (plane) of the silicon wafer. A thin film
of silicon dioxide is grown on top of the wafer to
insulate the exposed junctions after the leads
have been attached (i.e., the transistor is passivated).
Planck constant Symbol, h. Unit, joule-second.
The constant of proportionality in the fundamental
law of the quantum theory, stating that
radiant energy is composed of quanta proportional
to the frequency of the radiation; h = q/f =
6.62608 × 10 –34 J•s, where q is the value of the
quantum and f is the frequency in Hz.
Collector
Base
Emitter
n
p
n
planar transistor
Oxide
film
plane of polarization The plane containing the direction
of propagation and the electric field vector
of a plane-polarized wave (see POLARIZATION, 3
and POLARIZED LIGHT).
plane-polarized light See POLARIZATION, 3 and
POLARIZED LIGHT.
plane-reflector antenna A directive antenna in
which the reflector is a sheet of metal or a metal
screen. In a corner-reflector antenna, the reflector
is a folded sheet, or two sheets joined along
one edge.
planetary electron See ORBITAL ELECTRON.
planimeter A mechanical instrument for measuring
the area of a closed figure. The outline of the
figure is traced with the pointer of the device, and
the area is read from a pair of dials. In this application,
the planimeter does the work of integral
calculus.
PLANNER A high-level computer programming
language sometimes used in artificial intelligence.
It is a “goal-oriented” language in that it
seeks a solution to a problem using various
schemes, as necessary.
plan position indicator Abbreviation, PPI. A radar
display on whose screen small spots of light reconstruct
the scanned vicinity, revealing objects,
such as buildings, boats, aircraft, etc. The distance
from the center of the screen to a spot depicts
the range of an object, and the radial angle
reveals its bearing.
plant In computer operations, to put the result of
an operation specified by a routine in a storage
location from which it will be taken for implementation
of an instruction further on in the program.
plaque resistor A flat, noninductive, power resistor,
often used as a dummy load during highfrequency
power measurements.
plasma A usually high-temperature gas that is so
highly ionized that it is electrically conductive
and susceptible to magnetic fields; it is recognized
as one of the states of matter. Also see
PHYSICAL PROPERTIES.
plasma diode A diode in which a plasma substance
produces conduction in one direction, but
not in the other.