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POLARITY—(1) The condition in an electrical circuit by which the direction of the flow of current can be
determined. Usually applied to batteries and other direct voltage sources. (2) Two opposite charges, one
positive and one negative. (3) A quality of having two opposite magnetic poles, one north and the other
south [1] [13].
POLARIZATION—(1) The effect of hydrogen surrounding the anode of a cell, which increases the
internal resistance of the cell [1]. (2) The magnetic orientation of molecules in a magnetizable material
in a magnetic field, whereby tiny internal magnets tend to line up in the field [2].
POLAR ORBIT—An orbit that has an angle of inclination of or near 90 degrees [17].
POLE—(1) The number of points at which current can enter a switch; for example, single pole, double pole,
and three pole [3]. (2) The sections of a field magnet where the flux lines are concentrated; also where
they enter and leave the magnet [5].
POLE PIECE—(1) A piece of ferromagnetic material used to control the distribution of magnetic lines of
force; that is, it concentrates the lines of force in a particular place or evenly distributes the lines of
force over a wide area [3]. (2) The shaped magnetic material upon which the stator windings of motors
and generators are mounted or wound [5].
POLYMER FUME FEVER—A flu-like condition caused by a person breathing the vapors of
fluorocarbons when they are heated. Sometimes called FOUNDRYMAN'S FEVER [4].
POLYPHASE—A term that describes systems or units of a system that are activated by or which generate
separate out-of-phase voltages. Typical polyphase systems are 2-phase and 3-phase; their voltages are
90- and 120-degrees out of phase, respectively. This term means the same as MULTIPHASE [5].
POSITIONAL NOTATION—A numbering system in which a number is represented by means of a stated
set of symbols or digits, such that the value contributed by each symbol or digit depends upon its
position as well as upon its value [13].
POSITIONAL WEIGHTING—The value given a digit based on the digit's position within a given number
[13].
POSITION SENSOR—A component in a servosystem that measures position and converts the
measurement into a form convenient for transmission as a feedback signal [15].
POSITION SERVOSYSTEM—A servosystem whose end function is to control the position of the load it
is driving [15].
POSITIVE ALTERNATION—The part of a sine wave that is above the reference line [2] [10] [12].
POSITIVE CLAMPER—A circuit that clamps the lower extremity of the output waveshape to a dc
potential of 0 volts [9].
POSITIVE FEEDBACK—Feedback in which the feedback signal is in phase with the input signal. Also
called REGENERATIVE FEEDBACK [8].
POSITIVE LOGIC—The form of logic in which the more positive logic level represents 1 and the more
negative level represents 0 [13].
POSITIVE TEMPERATURE COEFFICIENT—The characteristic of a conductor in which the resistance
increases as temperature increases [7].
