The Illustrated Dictionary of Electronics - Loscha

polarizing filter • polygraph 543through it to be polarized in any particular planebetween horizontal and vertical, depending onthe degree of rotation. Also see POLARIZEDLIGHT.polarography In chemistry, a form of qualitative orquantitative analysis utilizing IE curves obtainedwhen the voltage is gradually increased across asolution in ELECTROLYSIS.polar orbitAn orbit that carries a satellite over thegeographic polar regions of the earth. This type oforbit is oriented at, or nearly at, 90 degrees withrespect to the equator, and can have a periodranging from about 90 minutes to several weeksor even months. Low-earth-orbit (LEO) satellitesgenerally have such orbits.EquatorSatelliteorbitNorthpolepolar orbitEarthpolar-orbiting satellite Any satellite in a POLARORBIT.polar planimeter See PLANIMETER.polar relay See POLARIZED RELAY.polar response The horizontal-plane directionalresponse of an antenna or other transducer.pole 1. An extremity or terminus that possessesPOLARITY. Examples: magnetic pole and electricpole. 2. The movable member of a switch. 3. Oneof the frequencies at which a transfer functionbecomes infinite.pole face The smooth end surface of a pole piece.pole piece 1. A section of specially shaped iron orsteel that is attached to a magnetic core. 2. Halfof a two-piece magnetic core that terminates in apole.pole shoe In an electric motor, the section of thefield pole nearest the armature.poles of impedance For a reactive network, thefrequencies at which the impedance is infinite.Compare ZEROS OF IMPEDANCE.poles of network function The values at which anetwork function is infinite. Compare ZEROS OFNETWORK FUNCTION.poles of transfer function The frequencies atwhich a transfer function becomes infinite. CompareZEROS OF TRANSFER FUNCTION.police robot A proposed robotic machine, eitherautonomous or remotely controlled (teleoperated),that would be used to assist in law enforcement,particularly in dangerous operations.poling The deliberate adjustment of electromagnetic-fieldpolarity.Polish notation In Boolean algebra, a form of notationwherein the variables in a statement arepreceded by the operators.polling In data transmission, a technique in whichchannels being shared by more than one terminalare tested to find one over which data iscoming in, or to ascertain which is free fortransmission.polonium Symbol, Po. A radioactive metallic element.Atomic number, 84. Atomic weight, approximately209.polychromatic radiation 1. Visible-light radiationhaving more than one wavelength; in particular,covering a broad range of wavelengths. 2. Electromagneticradiation over a broad band of wavelengths.polycrystalline material A substance, such as asemiconductor, of which even a very smallsample consists of a number of separate crystalsbound tightly together. Compare SINGLE-CRYSTAL MATERIAL.polydirectional microphone See OMNIDIREC-TIONAL MICROPHONE.polyelectrolyte An ELECTROLYTE having highmolecular weight.polyester A resin made by reacting a dihydroxy alcoholwith a dibasic acid.polyester backing A polyester tape on the surfaceof which iron oxide is deposited to yield a magneticrecording tape.polyethylene A plastic insulating material. Dielectricconstant, 2.2. Dielectric strength, 585 V/mil.polyethylene disc A phonograph disc made ofpolyethylene.polygonal coil A coil wound on a form having apolygonal, rather than circular cross section.Some polygonal forms have as many as 12 sidesin cross section.polygraph An instrument for measuring andrecording electrical signals proportional to bloodpressure, skin resistance, breathing rate, andother reactions that vary under emotional stress.Also called LIE DETECTOR. Compare PATHOME-TER.