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PICO—A prefix adopted by the National Bureau of Standards meaning 10
-12
[1].
PICTORIAL DIAGRAM—A diagram showing actual pictorial sketches of the various parts of an
equipment and the electrical connections between the parts [4].
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 [1].
PIP (BLIP)—On a CRT display, a spot of light or a baseline irregularity representing the radar echo [18].
PITCH—A term used to describe the frequency of a sound heard by the human ear [10].
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 [6].
PLANE OF POLARIZATION—The plane (vertical or horizontal), with respect to the earth, in which the
E field propagates [10].
PLANE WAVEFRONTS—Waves of energy that are flat, parallel planes and are perpendicular to the
direction of propagation [18].
PLANNED-POSITION INDICATOR—A radar display in which range is indicated by the distance of a
bright spot or pip from the center of the screen and the bearing is indicated by the radial angle of the
spot [18].
PLATE—(1) One of the electrodes in a storage battery [1]. (2) One of the electrodes in a capacitor [2]. (3)
The principal electrode to which the electron stream is attracted in an electron tube [6].
PLATE DISSIPATION—The amount of power lost as heat in the plate of a vacuum tube [6].
PLATE KEYING—A keying system in which the plate supply is interrupted [12].
PLATE MODULATOR—An electron-tube modulator in which the modulating voltage is applied to the
plate circuit of the tube [12].
PLATE RESISTANCE—The plate voltage change divided by the resultant plate current change in a
vacuum tube, all other conditions being fixed [6].
POINT BENDER—A tool used to adjust the contact spacing on a relay [3].
POINT-CONTACT DIODE—A diode in which the end of a fine wire is pressed against a semiconductor.
Used as a detector or mixer over the microwave region [7].
POINT OF ZERO DISPLACEMENT—See REFERENCE LINE [10].
POINT-TO-POINT WIRING—Individual wires run from terminal to terminal to complete a circuit [14].
POLAR—The teletypewriter operation in which current flow of one polarity represents a mark, and current
of the opposite polarity represents a space [17].
POLAR-COORDINATE GRAPH—A graph with a pair of axes. One consists of a series of circles with a
common center, and the other consists of a rotating radius extending from the center of the concentric
circles [10].
