P2

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
Travelling 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 attatching 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.

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