paper capacitor - Fixed capacitor using oiled or waxed paper as a dielectric.
parallel - Circuit having two or more paths for current flow. Also called shunt.
parallel resonant circuit - Circuit having an inductor and a capacitor in parallel with one another. Circuit offers a high impedance at resonant frequency. Sometimes called a "tank circuit."
pass band - The range of frequencies that will be passed and amplified by a tuned amplifier. Also the range of frequencies passed by a band pass filter.
passive component - Component that does not amplify a signal. Resistors and capacitors are examples.
passive filter - A filter that contains only passive or non amplifying components.
passive system - System that emits no energy. It only receives. It does not transmit or reveal its position.
peak - Maximum or highest amplitude level.
peak inverse voltage - (PIV) The maximum rated value of a AC voltage acting in the direction opposite to that in which a device is designed to pass current.
peak to peak - Difference between the maximum positive and maximum negative values of an AC waveform.
pentavalent element - Element whose atoms have five valence electrons. Used in doping intrinsic silicon or germanium to produce n-type semiconductor material. Most commonly used pentavalent materials are arsenic and phosphorus.
percent of regulation - The change in output voltage that occurs between no-load and full-load in a DC voltage source. Dividing this change by the full-load value and multiplying the result by 100 gives percent regulation.
percent of ripple - The ratio of the effective rms value of ripple voltage to the average value of the total voltage. Expressed as a percentage.
period - Time to complete one full cycle of a periodic or repeating waveform.
permanence - Magnetic equivalent of magnetic inductance and consequently equal to the reciprocal of reluctance, just as conductance is equal to the reciprocal of resistance.
permanent magnet - Magnet normally made of hardened steel that retains its magnetism indefinitely.
permeability - Measure of how m how much better a material is as a path for magnetic lines of force with respect to air which has a permeability of one. Symbolized by the Greek lower case letter mu (m).
phase - Angular relationship between two waves.
phase angle - Phase difference between two or more waves, normally expressed in degrees.
phase shift - Change in phase of a wave form between two points, expressed as degrees of lead or lag.
phase shift oscillator - An oscillator that uses three RC networks in its feedback path to produce the 180° phase shift required for oscillation.
phase splitter - Circuit that takes a single input signal and produces two output signals that are 180° apart in phase.
phonograph - Piece of equipment used to reproduce sound stored on a disk called a phonograph record.
phosphor - Luminescent material applied to the inner face of a cathode ray tube that when bombarded with electrons will emit light of various colors.
photoconductive cell - Material whose resistance decreases or conductance increases when exposed to light.
photoconduction - A process by which the conductance of a material is change by incident electromagnetic radiation in the visible light spectrum.
photo detector - Component used to detect or sense light.
photodiode - A semiconductor diode that changes its electrical characteristics in response to illumination.
photometer - Meter used to measure light intensity.
photon - Discrete portion of electromagnetic energy. A small packet of light.
photoresistor - Also known as a photoconductive cell or light dependent resistor. (LDR) A device whose resistance decreases with exposure to light.
photovoltaic cell - Component commonly called a solar cell used to convert light energy into electrical energy.
pi - Value representing the ratio between the circumference and diameter of a circle and equal to approximately 3.142.
pierce oscillator - A variation of the colpitts oscillator. This oscillator uses a quartz crystal in place of the inductor found in the colpitts oscillator feedback network. The crystal maintains a highly stable output frequency.
piezoelectric crystal - Crystal material that will generate a voltage when mechanical pressure is applied and conversely will undergo mechanical stress when subjected to a voltage.
piezoelectric effect - The production of a voltage between opposite sides of a piezoelectric crystal as a result of pressure or twisting. Also the reverse effect which the application of a voltage to opposite sides causes a deformation to occur at the frequency of the applied voltage. (Converts mechanical energy into electrical energy and electrical energy into mechanical energy.)
pinch-off region - A region on the characteristic curve of a FET in which the gate bias causes the depletion region to extend completely across the channel.
plastic film capacitor - Capacitor in which alternate layers of aluminum foil are separated by thin films of plastic
plate - Conductive electrode in either a capacitor or battery. In vacuum tube technology, it is the name given to the anode.
plug - Movable connector that is normally connected into a socket or jack.
pnp transistor - A bipolar junction transistor with an n-type base and p-type emitter and collector.
pole - In an active filter, a single RC circuit. A one pole filter has one capacitor and one resistor. A two pole filter has two RC circuits and so on.
polar coordinates - Either of two numbers that locate a point in a plane by its distance from a fixed point and the angle this line makes with a fixed line.
polarity - Term used to describe positive and negative charges.
polarized - A component which must be connected in correct polarity to function and/or d/or prevent destruction. Example: Electrolytic capacitor.
positive - Polarity of point that attracts electrons as opposed to negative which supplies electrons.
positive charge - A charge that exists in a body that has fewer electrons than protons.
positive feedback - A feedback signal that is in phase with an amplifier input signal. Positive feedback is necessary for oscillation to occur.
positive ground - A system whereby the positive terminal of the source is connected to the system's conducting chassis.
positive ion - Atom that has lost one or more valence electrons resulting in a net positive charge.
potential difference - Voltage difference between two points which will cause current to flow in a closed circuit.
potential energy - Energy that has potential to do work because of its position relative to others.
potentiometer - A variable resistor with three terhree terminals. Mechanical turning of a shaft can be used to produce variable resistance and potential. Example: A volume control is usually a potentiometer.
power - Amount of energy converted by a circuit or component in a unit of time, normally seconds. Measured in units of watts. (joules/second).
power amplifier - An amplifier designed to deliver maximum power output to a load. Example: In an audio system, it is the power amplifier that drives the loudspeaker.
power derating factor - A transistor rating that tells how much the maximum allowable value of PD decreased for each 1°C rise in ambient temperature.
power dissipation - Amount of heat energy generated by a device in one second when current flows through it.
power factor - Ratio of actual power to apparent power.
power loss - Ratio of power absorbed to power delivered.
power supply - Electrical equipment used to deliver either AC or DC voltage.
power supply rejection ratio - A measure of an op-amps ability to maintain a constant output when the supply voltage varies.
primary - First winding of a transformer. Winding that is connected to the source as opposed to secondary which is a winding connected to a load.
primary cell - Cell that produces electrical energy through an internal electrochemical action. Once discharged a primary cell cannot be reused.
printed circuit board - Insulating board containing conductive tracks for circuit connections.
programmable UJT - Unijunction transistor with a variable intrinsic stand-off ratio.
propagation - Traveling of electromagnetic, electrical or sound waves through a medium.
propagation delay - Time required for a signal to pass through a device or circuit.
propagation time - Time required for a wave to travel between two points.
protoboard - Board with provision for attaching components without solder. Also called a breadboard. Primarily used for constructing experimental circuits.
proton - Sub atomic particle within the nucleus of an atom. Has a positive charge.
pulse - Rise and fall of some quantity (usually voltage) for a period of time.
pulse fall time - Time for a pulse to decrease from 90% of its peak value to 10% of its peak value.
pulse repetition frequency - The number of times per second that a pulse is transmitted. Pulse rate.
pulse repetition time - Time interval between the start of two consecutive pulses.
pulse rise time - Time required for a pulse to increase from 10% of its peak value to 90% of its peak value.
pulse width - Time interval between the leading edge and trailing edge of a pulse at a point where the amplitude is 50% of the peak value.
push>push-pull amplifier - Amplifier using two active devices operating 180° apart.
Pythagorean theorem - A theorem in geometry: The square of the hypotenuse of a right triangle equals the sum of the squares of the other two sides. In electronics used for vector analysis of AC circuits