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Glossary of Physics Terms beginning with letter P
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parent noun One of the two persons from whom one is immediately biologically descended; a mother or father. A person who acts as a parent in rearing a child. (adoptive parent, foster parent) (biology) An organism from which a plant or animal is immediately biologically descended. The source or origin of something. A group from which another group is formed, or which completely controls a subordinate group. (parent company) In object oriented computer programming, the object from which a child or derived object is descended The child object inherits methods and data fields from the parent. partial vacuum noun a region of low atmospheric pressure, especially one in which most of the air has been pumped out particle accelerator noun (plural particle accelerators) A device that accelerates electrically charged particles to extremely high speeds, for the purpose of inducing high energy reactions or producing high energy radiation. Pascal proper noun The French mathematician and physicist w:Blaise_Pascal, Blaise Pascal. The w:Pascal_programming_language, Pascal programming language. Pascal's law noun Pascal"s law (physics) The law that states that a confined fluid transmits externally applied pressure uniformly in all directions; the basis of hydraulics. (trans-top, physical law) Czech: PascalÅ¯v zí¡kon (trans-mid) (trans-bottom) Paschen-Back effect noun (physics) a form of the Zeeman effect that affects the spectral lines obtained when a light source is placed in a very strong magnetic field PC initialism (plural PCs for countable noun senses) (US Navy) w:Coastal Patrol, Coastal Patrol partially continuous w:Penn Central, Penn Central personal computer photocopy w:Phrozen Crew, Phrozen Crew (UK politics) w:Plaid Cymru, Plaid Cymru player character (UK, Canada) police constable politically correct political correctness polycarbonate posterior commissure w:Presbyterian Church, Presbyterian Church Privy Council privy councillor probable cause Probate Court pro-choice (TV) production code Professional Corporation (Canada) w:Progressive Canadian Party, Progressive Canadian Party (Canada, formerly) w:Progressive Conservative, Progressive Conservative progressive contextualization Proto-Celtic pubococcygeus muscle Peltier effect noun (Physics) a thermodynamic effect which occurs when current is passed through a thermocouple, used in computing as a cooling process penetrometer noun A mechanical device that measures the ease of penetration of an object into a semisolid A device that measures the penetrating power of electromagnetic radiation (especially X-rays) period noun (context, now mostly, North America) Punctuation mark ending a sentence or marking an abbreviation. <!-- What languages does this apply to? All? Or just most? Should it be adjective appropriate, Appropriate for a given historical era. 2004, Mark Singer, Somewhere in America, Houghton Mifflin, page 70 :As the guests arrived — there were about a hundred, a majority in attire — I began to feel out of place in my beige summer suit, white shirt, and red necktie. Then I got over it. I certainly didn't suffer from Confederate-uniform envy. periodic adjective Relative to a period or periods. Having repeat, repeated cycle, cycles. Occurring at regular interval, intervals. Pertaining to the revolution of a celestial object in its orbit. Periodical. phase noun That which is exhibited to the eye; the appearance which anything manifests, especially any one among different and varying appearances of the same object. Any appearance or aspect of an object of mental apprehension or view The problem has many phases. (astronomy) A particular appearance or state in a regularly recurring cycle of changes with respect to quantity of illumination or form, or the absence, of its enlightened disk; as, the phases of the moon or planets. Illustrated in W:Lunar phase, Wikipedia's article Lunar phase. Any one point or portion in a recurring series of changes, as in the changes of motion of one of the particles constituting a wave or vibration; one portion of a series of such changes, in distinction from a contrasted portion, as the portion on one side of a position of equilibrium, in contrast with that on the opposite side. verb (phas, ing) (to phase out) To discontinue (doing) something over a period of time (i.e., in phases). (transitive) To stun or shock someone. (intransitive) To become stunned or shocked. phase velocity noun (physics) the velocity of propagation of a pure sine wave of infinite extent and infinitesimal amplitude phon noun A unit of apparent loudness, equal in number to the intensity in decibels of a 1,000-hertz tone judged to be as loud as the sound being measured. phonon noun (particles) The quantum of acoustic or vibrational energy (sound), considered a discrete particle. phonoscope noun a device that shows an image representing the acoustical properties of a musical instrument etc. phosphoresce verb to phosphoresce to exhibit phosphorescence phosphorescent noun A phosphorescent substance. adjective Having the property of emitting light for a period of time after the source of excitation is taken away, e.g., in electrostatic storage tubes and cathode-ray tubes. photoconductive adjective of, relating to, or characterized by photoconductivity photodisintegration noun (physics) Any nuclear reaction, especially a nuclear fission, initiated by absorption of high-energy electromagnetic radiation such as a gamma ray photoelasticity noun a technique for studying and measuring the stresses and strains in an object by means of mechanical birefringence photoelectric effect noun (physics) The emission of electrons from the surface of a material following the absorption of electromagnetic radiation photoelectron noun (physics) An electron ejected from the surface of a material by the photoelectric effect photoemission noun (physics) the ejection of electrons from the surface of a solid by incident electromagnetic radiation photofission noun (physics) nuclear fission as the result of the absorption of a gamma ray or other high-energy photon photoionization noun alternative spelling of photoionisation photoluminescence noun (physics) luminescence following the absorption of a photon photon noun (particles) The quantum of light and other electromagnetic energy, regarded as a discrete particle having zero rest mass, no electric charge, and an indefinitely long lifetime. It is a gauge boson. photonegative adjective (biology) having a negative phototropic or phototactic response; repelled by light photoneutron noun (physics) Any neutron produced by a photonuclear reaction photonuclear adjective (physics) of or relating to any nuclear reaction involving a photon photopositive adjective (biology) having a positive phototropic or phototactic response; attracted by light photoproton noun (physics) Any proton produced in a photonuclear reaction photovoltaic effect noun (physics) the conversion of electromagnetic radiation into electric power through absorption by a semiconducting material physical noun Physical examination. How long has it been since your last physical? adjective (wikipedia, Physical) Having to do with the body. Are you feeling any physical effects? Having to do with the material world. It's not so much a physical place as a state of mind. Involving bodily force. This team plays a very physical game, so watch out. Having to do with physics. This substance has a number of interesting physical properties. physicist noun A person whose occupation specializes in the science of physics, especially at a professional level. physics noun The branch of science concerned with the study of properties and interactions of space, time, matter and energy. piezometer noun An instrument used to measure high pressures pile noun A hair; hence, the fiber of wool, cotton, and the like; also, the nap when thick or heavy, as of carpeting and velvet. Velvet soft, or plush with shaggy pile. —Cowper A covering of hair or fur. A large stake, or piece of timber, steel section pointed and driven into the earth or drilled and cast reinforced concrete, as at the bottom of a river, or in a harbor where the ground is soft, for the support of a building, a pier, or other superstructure, or to form a cofferdam, etc. The head of an arrow or spear. (heraldry) One of the ordinaries or subordinaries having the form of a wedge, usually placed palewise, with the broadest end uppermost. A mass of things heaped together; a heap; as, a pile of stones; a pile of wood. A mass formed in layers; as, a pile of shot. A funeral pile; a pyre. A large building, or mass of buildings. A bundle of pieces of wrought iron to be worked over into bars or other shapes by rolling or hammering at a welding heat; a fagot. A vertical series of alternate disks of two dissimilar metals, as copper and zinc, laid up with disks of cloth or paper moistened with acid water between them, for producing a current of electricity; — commonly called Volta"s pile, voltaic pile, or galvanic pile. The reverse (or tails) of a coin. (Obs) A hemorrhoid (usually it is in plural) pinch effect noun (physics) the magnetic self-attraction of parallel electric currents having the same direction; the restriction of a flowing plasma because of this attraction pion noun (particles) Any of three semistable mesons, having positive, negative or neutral charge, now known to be composed of a quark and an antiquark. <!-- either Ï€⁰, a neutral form with a mass 264 times that of an electron, or Ï€⁺ or Ï€^—, a charged form with a mass 273 times that of an electron. Note: Ï€⁺ is a combination of an up quark and a down antiquark, Ï€^— is a combination of an up antiquark and a down quark, Ï€⁰ is a quantum mixture of an up quark, up antiquark pair and a down quark, down antiquark pair !--> Planck's constant noun (physics) the constant of proportionality relating the energy and frequency of a photon (6.626 x 10^-34 joule-seconds); also related to the indeterminacy limit in the Heisenberg uncertainty principle plasma noun (physics) A state of matter consisting of fully ionized gas A clear component of blood or lymph containing fibrin blood plasma, Blood plasma, free of suspended cells, used in transfusions plastic flow noun (physics) any fluid flow in which movement is proportional to the applied force (above the yield value) (geology) any deformation caused by a sustained force plenum noun (pl2=plena) A space that is completely filled with matter 1974: He lay on the long stone slant down to the slapping waves, his denim shorts, sneakers, and socks under his head for a pillow, feeling the splendour of distance in all directions, the liquid silence, the of aloneness. " Guy Davenport Tatlin! A legislative meeting (especially of the Communist Party) in which all members are present An enclosed space having greater than atmospheric pressure The space above a false ceiling used for cables, ducts etc (computing) A type of network cabling which satisfies plenum-ratings issued by the National Electrical Code. These cables are safer in case of a fire, producing less smoke and fumes. pneumatic noun (gnosticism) In gnostic theologian Valentinus' triadic grouping of man the highest type; a person focused on spiritual reality (the other two being hylic and psychic). adjective Of, or related to air or other gases Of, or related to pneumatics Powered by, or filled with compressed air (zoology) Having cavities filled with air Spiritual; Of, or related to the pneuma (context, of a woman) well-rounded; full-breasted; bouncy (especially during sex) "Every one says I'm awfully pneumatic," said Lenina reflectively, patting her own legs. - Aldous Huxley - Brave New World (chapter 6) pneumatics noun The branch of mechanics that deals with the mechanical properties of gases poise noun (uncountable) A state of balance, equilibrium or stability Composure; freedom from embarrassment or affectation mien; bearing or deportment of the head or body A condition of hovering, or being suspended (physics) A cgs unit of dynamic viscosity equal to one dyne-second per square centimeter. verb to poise (poises, poised, poising) To balance or to hover To draw up into readiness Poisson's ratio noun Of a material in tension or compression, the ratio of the strain in the direction of the applied load to the strain normal to the load. Abbreviated Î½. porous adjective Full of tiny pores that allow fluids or gasses to pass through. Sponges are so they can filter water while trapping food. Concrete is , so water will slowly filter through it. (Of legislation): full of loopholes positron noun (particles) The antimatter equivalent of an electron, having the same mass but a positive charge potential energy noun the energy possessed by an object because of its position (in a gravitational or electric field), or its condition (as a stretched or compressed spring, as a chemical reactant, or by having rest mass) pound-force noun A unit of force equal to a mass of one avoirdupois pound times a standard acceleration of gravity, equal to about 4.44822 newtons. Symbol lbf or lb_f. PPS abbreviation Post Postscript Polyphenylene Sulfide pressure noun (countable and uncountable; plural: pressures) (physics) The amount of force that is applied over a given area divided by the size of this area. Units SI: pascal (Pa) (1 pascal equals 1 newton per square metre) Others: bar (1 bar equals 100000 pascals), barye (Ba) (1 barye equals 0.1 pascal), pounds per square inch (psi, lbf/in², lb/in²), torr, mmHg, atmosphere (atm) mental strain caused by one's own or others' expectations on one's own performance She has been under lately because her boss expects her to get the job done two weeks early. Synonyms - under the pump, under the gun pressurize verb (pressuriz, es) To put pressure on; to put under pressure. proton noun (particles) A positively charged subatomic particle forming part of the nucleus of an atom and determining the atomic number of an element; the nucleus of the most common isotope of hydrogen; composed of two up quarks and a down antiquark PSI initialism Pounds per square inch. Pre-Sentence Investigation. Protein Structure Initiative. Pollutant Safety Index or Pollutant Standard Index (Measuement of the air pollutant such as haze) PSIG initialism pounds, Pounds per square inch, gauge (unit of pressure) pulse noun Any annual legume yielding from 1 to 12 grains or seeds of variable size, shape and colour within a pod, and used as food for humans or animals. (physiology) A normally regular beat felt when arteries are depressed, caused by the pumping action of the heart. A beat, throb. (music) A periodically recurring short stimulus, perceived as points in time. (DeLone? et. al. (Eds.), 1975, chap. 3) Often the stimuli are defined as identical (Cooper & Meyer, 1960). (rfc, music definition needs rewritten because the current one is copyrighted) pyromagnetic adjective (obsolete) that functions as a result of heat and magnetism

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