"A"
"B"
"C",
"D",
"E",
"F",
"G",
"H",
"I",
"J",
"K",
"L",
"M",
"N",
"O",
"P"
"Q",
"R",
"S",
"T",
"U",
"V",
"W",
"X",
"Y",
"Z"
Previous set of "P" terms and definitions
PHOTOCELL. A light-controlled variable resistor which has a light-to-dark resistance ratio of 1:1000.
PHOTODIODE. A light-controlled PN junction. Current flow increases when the PN junction is exposed
to an external light source. A semiconductor diode that produces, as
a result of the absorption of photons, (a) a photovoltage or (b) free carriers that support the
conduction of photocurrent. Photodiodes are used for the detection of optical communication
signals and for the conversion of optical power to electrical power. [Diode Manufacturers]
PHOTOELECTRIC VOLTAGE. A voltage produced by light.
PHOTOETCHING. Chemical process of removing unwanted material in producing printed circuit boards.
PHOTOTRANSISTOR. An optoelectronic device that conducts current when exposed to light. Produces
more current and is much more sensitive to light than the photodiode.
PHOTOVOLTAIC CELL (SOLAR CELL). A device that acts much like a battery when exposed to
light and converts light energy into electrical energy.
PHYSICAL BLOCK ADDRESS. [PBA] The PBA is the fixed, physical address of a block of data on the flash drive.
PICO. A prefix adopted by the National Bureau of Standards meaning 10-12. Engineering Notation
PIEZOELECTRIC EFFECT. The effect of producing a voltage by placing a stress, either by
compression, expansion, or twisting, on a crystal and, conversely, producing a stress in a crystal by
applying a voltage to it.
Pigtail. Short wires which are connected to terminals on receptacles or switches..
PIN DIODE. Acronym for positive-intrinsic-negative diode. A photodiode with a large, neutrally doped
intrinsic region sandwiched between p-doped and n-doped semiconducting regions. Note: A PIN diode
exhibits an increase in its electrical conductivity as a function of the intensity, wavelength, and
modulation rate of the incident radiation. Diode Manufacturers Listing
PITCH. A term used to describe the frequency of a sound heard by the human ear.
PLANAR TUBE. An electron tube, constructed with parallel electrodes and a ceramic envelope, that is
used at uhf frequencies. It is commonly referred to as a lighthouse tube.
PLANE OF POLARIZATION. The plane (vertical or horizontal), with respect to the earth, in which the
E field propagates.
PLANE WAVEFRONTS. Waves of energy that are flat, parallel planes and are perpendicular to the
direction of propagation.
PLATE. One of the electrodes in a storage battery. One of the electrodes in a capacitor. The principal electrode to which the electron stream is attracted in an electron tube.
PLATE DISSIPATION. The amount of power lost as heat in the plate of a vacuum tube.
PLATE KEYING. A keying system in which the plate supply is interrupted.
PLATE MODULATOR. An electron-tube modulator in which the modulating voltage is applied to the
plate circuit of the tube.
PLATE RESISTANCE. The plate voltage change divided by the resultant plate current change in a vacuum tube, all other conditions being fixed.
PLD. Acronym for Programmable Logic Device. PLDs are devices that are programmed by the OEM customer or manufacturer. A PLD IC is normally considered to be one of the more basic Programmable Logic Devices having only a few logic elements to several dozen logic elements How ever, some consider FPGA devices to also be a PLD, even with several thousand logic elements. There are two main types of PLD devices; Simple PLD [SPLD], and Complex PLD [CPLD]. The most widely know PLD is the 22V10, having 10 Flip Flop I/O programmable blocks. [PLD Dictionary], [PLD Manufacturers]
PLENUM. The air return path of a central air handling
system, either ductwork or open space over a suspended
ceiling.
PLENUM CABLE. Cable approved by a recognized agency
such as UL for installation in plenums without the need for
conduit.
Next set of "P" Terms in the Engineering Glossary
