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PART 17 GLOSSARY

ACTIVE FILTER

A frequency-selective circuit consisting of active devices such as transistors or op-amps combined with reactive (RC) circuits.

ADMITTANCE (Y)

A measure of the ability of a reactive circuit to permit current; the reciprocal of impedance with a unit, siemens (S)

ALPHA ()

The ratio of collector current to emitter current in a bipolar junction transistor.

ALTERNATING CURRENT

Current that reverses direction in response to a change in source voltage polarity.

AMERICAN WIRE GAGE (AWG)

A standardization based on wire diameter.

AMMETER

An electrical instrument used to measure current.

AMPERE

The unit of electrical current.

AMPERE-HOUR RATING

A number given in ampere-hours determined by multiplying the current in amps (A) times the length of time in hours (h) a battery can deliver that current to a load.

AMPERE-TURN

The unit of magnetomotive force (mmf).

AMPLIFICATION

The process of producing a larger voltage, current or power using a smaller input signal as a pattern.

AMPLIFIER

An electronic circuit having the capability of amplification and designed specifically for that purpose.

AMPLITUDE

The maximum value of a voltage or current.

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ANODE

The most positive terminal of a diode or other electronic device.

APPARENT POWER (Pa)

The product of the voltage times the current, expressed in volt-amperes (VA). In a purely resistive circuit, it is the same as the true power.

APPARENT POWER RATING

The method of rating transformers in which the power capability is expressed in volt-amperes (VA).

ATOM

The smallest particle of an element possessing the unique characteristics of that element.

ATOMIC NUMBER

The number of protons in the nucleus of an atom.

ATOMIC WEIGHT

The number of protons and neutrons in the nucleus of an atom.

ATTENUATION

A gain less than unity.

AUTOTRANSFORMER

A transformer in which the primary and secondary windings are in a single winding.

AVERAGE VALUE

The average of a sine wave over one half-cycle. It is 0.637 times the peak value.

BAND-PASS FILTER

A filter that passes a range of frequencies lying between two cutoff frequencies and rejects frequencies above and below the range.

BAND-STOP FILTER

A filter that rejects a range of frequencies lying between two cutoff frequencies and passes frequencies above and below the range.

BANDWIDTH (BW)

The characteristic of a certain electronic circuits that specifies the usable range of frequencies for which signals pass from input to output without significant reduction in amplitude.

BARRIER POTENTIAL

The inherent voltage across the depletion region of a pn junction.

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BASE

The smallest semiconducting regions in a bipolar junction transistor.

BASELINE

The normal level of a pulse waveform; the voltage level in the absence of a pulse.

BATTERY

An energy source that uses a chemical reaction to convert chemical energy into electrical energy.

BETA ()

The ratio of collector current to base current in a bipolar junction transistor.

BIAS

The application of a dc voltage to a diode or other electronic device to produce a desired mode of operation.

BLEEDER CURRENT

The current left after the total load current is subtracted from the total current into the circuit.

BRANCH

One current path in a parallel circuit.

CAPACITANCE

The ability of a capacitor to store electrical charge.

CAPACITIVE REACTANCE

The opposition of a capacitor to sinusoidal current. The unit is the ohm ().

CAPACITIVE SUSCEPTANCE (BC)

The ability of a capacitor to permit current; the reciprocal of capacitive reactance. The unit is the siemens(S).

CAPACITOR

An electrical device consisting of two conductive plates separated by an insulating material and possessing the property of capacitance.

CATHODE

The more negative terminal of a diode or other electronic devices.

CATHODE-RAY TUBE (CRT)

A vacuum tube device containing an electron gun that emits a narrow focused beam of electrons onto a phosphor-coated screen.

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CENTER TAP (CT)

A connection at the midpoint of the secondary winding of a transformer.

CHARGE

An electrical property of matter that exists because of an excess or a deficiency of electrons. Charge can be either positive or negative.

CHOKE

The term is used more commonly concerning inductors used to block or choke off high frequencies.

CIRCUIT

An interconnection of electrical components designed to produce a desired result. A basic circuit consists of a source, a load, and an interconnecting current path.

CIRCUIT BREAKER

A resettable protective device used for interrupting excessive current in an electric circuit.

CIRCUIT GROUND

A method of grounding whereby the metal chassis that houses the assembly or a large conductive area on a printed circuit board is used as the common or reference point; also called chassis ground.

CIRCULAR MILL (CM)

The unit of the cross-sectional area of a wire.

CLAMPER

A circuit that adds a dc level to an ac signal; a dc restorer.

CLASS A

A category of amplifier circuit that conducts for the entire input cycle and produces an output signal that is a replica of the input signal in terms of its wave shape.

CLASS B

A category of amplifier circuit that conducts for half of the input cycle.

CLASS C

A category of amplifier that conducts for a very small portion of the input cycle.

CLOSED CIRCUIT

A circuit with a complete current path.

CLOSED LOOP

An op-amp configuration in which the output is connected back to the input.

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CLOSED LOOP GAIN (Acl)

The overall voltage gain of an op-amp with feedback.

COEFFICIENT OF COUPLING (k)

a constant associated with transformers that is the ratio of secondary magnetic flux to primary magnetic flux. The ideal value of 1 indicates that all the flux in the primary winding is coupled into the secondary winding.

COIL

A common term for an inductor.

COLLECTOR

The largest region in a BJT which serves as the heat dissipation portion of the transistor.

COMMON BASE (CB)

A BJT amplifier configuration in which the base is the common (grounded) terminal.

COMMON-COLLECTOR (CC)

A BJT amplifier configuration in which the collector is the common (grounded) terminal.

COMMON-EMITTER (CE)

A BJT amplifier configuration in which the emitter is the common (grounded) terminal.

COMMON-MODE SIGNALS

Signals that appear the same on both inputs of an op-amp.

COMPARATOR

A circuit which compares two input voltages and produces an output in either of two states indicating the greater or less than relationship of the inputs.

CONDUCTANCE (G)

The ability of a circuit to allow current; the reciprocal of resistance. The unit is the siemens (S).

CONDUCTOR

A material in which electrical current is established with relative case. An example is copper.

COULOMB (C)

The unit of electrical charge.

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COULOMBS LAW

A physical law that states a force exists between two charged bodies that is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them.

COVALENT

Related to the bonding of two or more atoms by the interaction of their valence electrons.

CRYSTAL

The pattern or arrangement of atoms forming a solid material.

CURRENT

The rate of flow of charge (electrons).

CURRENT GAIN

The ratio of output current to input current.

CUTOFF

The no conducting state of a transistor.

CUTOFF FREQUENCY (c)

The frequency at which the output voltage of a filter is 70.7% of the maximum output voltage.

CYCLE

One repetition of a periodic waveform.

DARLINGTON PAIR

A two-transistor arrangement that produces a multiplication of current gain.

DC COMPONENT

The average value of a pulse waveform.

DECADE

A tenfold change in the value of a quantity. When a quantity becomes ten times less or ten times greater, it has changed a decade.

DECIBEL (dB)

The unit of logarithmic expression of a ratio, such as power ratio or a voltage ratio.

DEGREE

The unit of angular measure corresponding to 1/360 of a complete revolution.

DERIVATIVE

The instantaneous rate of change of a function determined mathematically.

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DIAD

A semiconductor device that can conduct current in other of two directions when properly activated.

DIELECTRIC

The insulating material between the plates of a capacitor.

DIELECTRIC CONSTANT

A measure of the ability of a dielectric material to establish an electric field.

DIELECTRIC STRENGTH

A measure of the ability of a dielectric material to withstand voltage without breaking down.

DIFFERENTIAL AMPLIFIER

An amplifier that produces an output proportional to the difference of two inputs.

DIFFERENTIATOR

A circuit that produces an output that approaches the mathematical derivative of the input, which is the rate of change.

DIODE

An electronic device that permits current in only one direction.

DISCRETE DEVICE

An individual electrical or electronic component that must be used in combination with other components to form a complete functional circuit.

DOPING

The process of imparting impurities to an intrinsic semiconductive material in order to control its conduction characteristics.

DRAIN

One of the three terminals of a field-effect transistor.

DUTY CYCLE

A characteristic of a pulse waveform that indicates the percentage of time that a pulse is present during a cycle, the ratio of pulse width to period.

EFFECTIVE VALUE

A measure of the heating effect of a sine wave; also known as the rms (root mean square) value.

EFFICIENCY

The ratio of the output power to the input power, expressed as a ratio.

ELECTRICAL

Related to the use of electrical voltage and current to achieve desired results.

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ELECTRICAL ISOLATION

The condition that exists when two coils are magnetically linked but have no electrical connection between them.

ELECTROMAGNETIC FIELD

A formation of a group of magnetic lines of force surrounding a conductor created by electrical current in the conductor.

ELECTROMAGNETIC INDUCTION

The phenomenon or process by which a voltage is produced in a conductor when there is relative motion between the conductor and a magnetic or electromagnetic field.

ELECTRON

The basic particle of electrical charge in matter. It possesses negative charge.

ELECTRONIC

Related to the movement and control of free electrons in semiconductors or vacuum devices.

EMITTER

One of the three regions in a BJT.

EMITTER-FOLLOWER

A popular term for a common-collector amplifier.

ENERGY

The fundamental ability to do work. The unit is the joule (J).

FALLING EDGE

The negative-going transition of a pulse.

FALL TIME

The time interval required for a pulse to change from 90% to 10 % of its full amplitude.

FARAD (F)

The unit of capacitance.

FARADAYS LAW

A law stating that the voltage induced across a coil of wire equals the number of turns in the coil times the rate of change of the magnetic flux.

FEEDBACK

The process of returning a portion of a circuits output signal to the input in such a way as to create certain specified operating conditions.

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FIELD-EFFECT TRANSISTOR (FET)

A type of transistor that uses an induced electric field within its structure to control current.

FILTER

A type of circuit that passes certain frequencies and rejects all others.

FREE ELECTRON

A valence electron that has broken away from its parent atom and is free to move from atom to atom within the atomic structure of a material.

FREQUENCY

A measure of the rate of change of a periodic function, the number of cycles completed in 1 s. The unit of frequency is the hertz.

FREQUENCY RESPONSE

In electrical circuits, the variation in the output voltage (or current) over a specified range of frequencies.

FULL-WAVE RECTIFIER

A circuit that converts an alternating sine wave into a pulsating dc consisting of both halves of a sine wave for each input cycle.

FUNDAMENTAL FREQUENCY

The repetition rate of a waveform.

FUSE

A protective device that burns open when there is excessive current in a circuit.

GAIN

The amount by which an electrical signal is increased or decreased; the ratio of output to input; the amount of amplification.

GATE

One of the three terminals of an FET.

GENERATOR

An energy source that produces electrical signals.

GERMANIUM

A semiconductive material.

GROUND

In electronic circuits, the common or reference point.

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HALF-POWER FREQUENCY

The frequency at which the output of a filter is 70.7% of maximum.

HALF-WAVE RECTIFIER

A circuit that converts an alternating sine wave into a pulsating dc consisting of one-half of a sine wave for each input cycle.

HARMONICS

The frequencies contained in a composite waveform, which are integer multiples of the repetition frequency (fundamental).

HENRY (H)

The unit of inductance.

HERTZ (Hz)

The unit of frequency and hence 1Hz equals one cycle per second.

HIGH-PASS FILTER

A certain type of filter whereby higher frequencies are passed and lower frequencies are rejected.

HOLE

The absence of an electron in the valence band of an atom.

HYSTERESIS

A characteristic of a magnetic material whereby a change in magnetization lags the application of a magnetic force.

IMPEDANCE (Z)

The total opposition to sinusoidal current expressed in ohms.

IMPEDANCE MATCHING

A technique used to match a load resistance to an internal source resistance in order to achieve a maximum transfer of power.

INDUCED VOLTAGE

Voltage produced as a result of a changing magnetic field.

INDUCTANCE (L)

The property of an inductor that produces an opposition to any change in current.

INDUCTIVE REACTANCE (XL)

The opposition of an inductor to sinusoidal current. The unit is the ohm.

INDUCTIVE SUSCEPTANCE (BL)

The reciprocal of inductive reactance and the unit is siemens

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INDUCTOR

An electrical device formed by a wire wound in a coil around a core having the property of inductance and the capability to store energy in its electromagnetic field; also known as a coil or a choke.

INSTANTANEOUS VALUE

The voltage or current value of a waveform at a given instant in time.

INSULATOR

A material that does not allow current under normal conditions.

INTEGRATOR

A circuit that produces an output that approaches the mathematical integral of the input.

INTERFACE

To make the output of one type of circuit compatible with the input of another so that they can operate properly together.

INTRINSIC SEMICONDUCTOR

A pure semiconductive material with relatively few free electrons.

ION

An atom that has gained or lost a valence electron resulting in a net positive or negative charge.

IONIZATION

The removal or addition of an electron from or to a neutral atom so that the resulting atom (called an ion) has a net positive or negative charge.

JOULE (J)

The unit of energy.

JUNCTION

A point at which two or more components are connected.

JUNCTION FIELD-EFFECT TRANSISTOR (JFET)

A type of FET that operates with a reverse-biased junction to control current in a channel.

KILOWATT-HOUR (kWh)

A common unit of energy used mainly by utility companies.

KIRCHHOFFS CURRENT LAW

A law stating that the total current into a junction equals the total current out of the junction.

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KIRCHHOFFS VOLTAGE LAW

A law stating that (1) the sum of the voltage drops around a closed loop equals the source voltage or (2) the sum of all the voltages (drops and sources) around a closed loop is zero.

LAG

Describes a condition of the phase or time relationship of waveforms in which one waveform is behind the other in phase or time.

LEAD

Describes a condition of the phase or time relationship of waveforms in which one waveform is ahead of the other in phase or time; also, a wire or cable connection to a device or instrument.

LEADING EDGE

The fist step or transition of a pulse.

LENZS LAW

A physical law that states when the current through a coil changes, an induced voltage is created in a direction to oppose the change in current. The current cannot change instantaneously.

LIGHT-EMITTING DIODE (LED)

A type of diode that emits light when there is forward current.

LIMITER

A circuit that removes part of a waveform above or below a specified level; a clipper.

LINEAR

Characterized by a straight-line relationship.

LINE REGULATION

The percent change in output voltage for a given change in line (input) voltage.

LOAD

An element (resistor or other components) connected across the output terminals of a circuit that draws current from the circuit.

LOAD REGULATION

The percent change in output voltage for a given change in load current.

LOW-PASS FILTER

A certain type of filter in which lower frequencies are passed and higher frequencies are rejected.

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MAGNETIC COUPLING

The magnetic connection between two coils as a result of the changing magnetic flux lines of one coil cutting through the second coil.

MAGNETIC FLUX

The lines of force between the north and south poles of a permanent magnet or an electromagnet.

MAGNETIC FLUX DENSITY

The number of lines of force per unit area perpendicular to a magnetic field.

MAGNETIZING FORCE

The amount of mmf per unit length of magnetic material.

MAGNETOMOTIVE FORCE

The force that produces a magnetic field.

MAGNITUDE

The value of a quantity, such as the number of volts of voltage or the number of amperes of current.

MAXIMUM POWER TRANSFER THEOREM

A theorem that states the maximum power is transferred from a source to a load when the load resistance equals the internal source resistance.

MOSFET

Metal oxide semiconductor field-effect transistor.

MULTIMETER

An instrument that measures voltage, current and resistance.

MUTUAL INDUCTANCE (LM)

The inductance between two separate coils, such as transformers.

NEGATIVE FEEDBACK

The return of a portion of the output signal to the input such that it is out of phase with the input signal.

NEUTRON

An atomic particle having no electrical charge.

OHM ()

The unit of resistance.

OHMMETER

An instrument for measuring resistance.

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OHMS LAW

A law stating that current is directly proportional to voltage and inversely proportional to resistance.

OPEN CIRCUIT

A circuit in which there is not a complete current path.

OPEN-LOOP GAIN (Aol)

The internal voltage gain of an op-amp without feedback.

OPERATIONAL AMPLIFIER

A special type of amplifier exhibiting very high open-loop gain, very high input impedance, very low output impedance, and good rejection of common-mode signals.

OSCILLATOR

An electronic circuit consisting of an amplifier and a phase-shift network connected in a positive feedback loop that produces a time-varying output signal using positive feedback.

OSCILLOSCOPE

A measurement instrument that displays signal waveforms on a screen.

PARALLEL

The relationship in electric circuits in which two or more current paths are connected between the same two points.

PARALLEL RESONANCE

In a parallel RLC circuit, the condition where the impedance is maximum and the reactance are equal.

PEAK INVERSE VOLTAGE (PIV)

The maximum value of reverse voltage which occurs at the peak of the input cycle when the diode is reversed-biased.

PEAK VALUE

The voltage or current value of a waveform at its maximum positive or negative points.

PEAK-TO-PEAK VALUE

The voltage or current value of a waveform measured from its minimum to its maximum points.

PERIOD (T)

The time interval of one complete cycle of a given sine wave or any periodic waveform.

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PERIODIC

Characterized by a repetition at fixed time intervals.

PERMEABILITY

The measure of ease with which a magnetic field can be established in a material.

PHASE

The relative displacement of a time-varying waveform in terms of its occurrence with respect to a reference.

PHASOR

A representation of a sine wave in terms of both magnitude and phase angle.

PHOTOCONDUCTIVE CELL

A type of variable resistor that is light-sensitive.

PHOTODIODE

A diode whose reverse resistance changes with incident light.

PINCH-OFF VOLTAGE

The value of the drain-to-source voltage of an FET at which the drain current becomes constant when the gate-to-source voltage is zero.

PN JUNCTION

The boundary between n-type and p-type semiconductive materials.

POLE

In practical terms, a single RC circuit in a filter or amplifier that causes the response to change at a 20 dB per decade rate above or below a certain frequency.

POSITIVE FEEDBACK

The return of a portion of the output signal to the input such that it is in phase with the input signal.

POTENTIOMETER

A three-terminal variable resistor.

POWER

The rate of energy usage.

POWER FACTOR

The relationship between volt-amperes and true power or watts. Volt-amperes multiplied by the power factor equals true power.

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POWER GAIN

The ratio of output power to input power; the product of voltage gain and current gain.

POWER RATING

The maximum amount of power that a resistor can dissipate without being damaged by excessive heat buildup.

POWER SUPPLY

An electronic instrument that produces voltage, current and power from the ac power line or batteries in a form suitable for use in powering electronic equipment.

PRIMARY WINDING

The input winding of a transformer; also called primary.

PROTON

A positively charged atomic particle.

PULSE

A type of waveform that consists of two equal and opposite steps in voltage or current separated by a time interval.

PULSE RESPONSE The reaction of a circuit to a given input.

PUSH-PULL

A type of class B amplifier in which one output transistor conducts for one half-cycle and the other conducts for the other half-cycle.

Q-POINT

The dc operating (bias) point of an amplifier.

QUALITY FACTOR (Q)

The ratio of reactive power to true power in a coil or a resonant circuit.

RAMP

A type of waveform characterized by a linear increase or decrease in voltage or current.

REACTIVE POWER

The rate at which energy is stored and alternately returned to the source by a capacitor or inductor. The unit is the VAR.

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RECOMBINATION

The process of a free electron falling into a hole in the valence band of an atom.

RECTIFIER

An electronic circuit that converts ac into pulsating dc; one part of a power supply.

REFLECTED LOAD

The load as it appears to the source in the primary of a transformer.

REFLECTED RESISTANCE

The resistance in the secondary circuit reflected into the primary circuit.

REGULATOR

An electronic circuit that maintains an essentially constant output voltage with a changing input voltage or load.

RELAY

An electromagnetically controlled mechanical device in which electrical contacts are open or closed by a magnetizing current.

RELUCTANCE

The opposition to the establishment of a magnetic field in a material.

RESISTANCE

Opposition to current and its unit is ohm.

RESISTOR

An electrical component designed specifically to provide resistance.

RESOLUTION

The smallest increment of a quantity that a meter can measure.

RESONANT FREQUENCY

The frequency at which a resonant condition occurs in a series or parallel RLC circuit.

RETENTIVITY

The ability of a material, once magnetized, to maintain a magnetized state without the presence of a magnetizing force.

REVERSE BREAKDOWN

The condition of a diode in which excessive reverse-bias voltage causes a rapid buildup of reverse current.

RHEOSTAT

A two terminal variable resistor.

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RIPPLE VOLTAGE

The small variation in the dc voltage on the output of a filtered rectifier caused by the slight charging and discharging action of the filter capacitor.

RISE TIME

The time interval required for a pulse to change from 10% to 90% of its amplitude.

RISING EDGE

The positive-going transition of a pulse.

ROLL-OFF

The decrease in the response of a filter below or above a critical frequency.

ROOT MEAN SQUARE (rms)

The value of a sine wave that indicates its heating effect, also known as the effective value. It is equal to 0.707 times the peak value.

SATURATION

The state of a BJT in which the collector current has reached a maximum and is independent of the base current.

SAWTOOTH WAVEFORM

A type of electrical waveform composed of ramps; a special case of a triangular waveform in which one ramp is much shorter than the other.

SCHEMATIC

A symbolized diagram of an electrical or electronic circuit.

SECONDARY WINDING

The output winding of a transformer; also called secondary.

SELECTIVITY

A measure of how effectively a filter passes certain frequencies and rejects others. The narrower the bandwidth, the greater the selectivity.

SEMICONDUCTOR

A material that has a conductance value between that of a conductor and that of an insulator. Silicon and germanium are examples.

SENSITIVITY FACTOR

The ohms-per-volt rating of a voltmeter.

SERIES

In an electrical circuit, a relationship of components in which the components are connected such as they provide a single current path between two points.

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SERIES RESONANCE

In a series RLC circuit, the condition where the impedance is minimum and the reactances are equal.

SHELL

An energy band in which electrons orbit the nucleus of an atom.

SHORT CIRCUIT

A zero or abnormally low resistance between two points; usually an inadvertent condition.

SILICON

a semiconductor element used in diodes and transistors with atomic number of 14

Silicon-controlled rectifier (SCR)

A device that can be triggered on to conduct current in one direction.

SOLENOID

An electromagnetically controlled device in which the mechanical movement of a shaft or plunger is activated by a magnetizing current.

SOURCE

Any device that produces energy, one of the three terminals of FET.

STEADY STATE

The equilibrium condition of a circuit that occurs after an initial transient time.

STEP-DOWN TRANSFORMER

A transformer in which the secondary voltage is less than the primary voltage.

STEP-UP VOLTAGE TRANSFORMER

A transformer in which the secondary voltage is greater than the primary voltage.

STOPBAND

The range of frequencies between the upper and lower cutoff points.

SUPERPOSITION

A method for analyzing circuits with two or more sources by examining the effects of each source by itself and then combining the effects.

SWITCH

An electrical or electronic device for opening and closing a current path.

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TANK CIRCUIT

A parallel resonant circuit.

TAPERED

Nonlinear, such as tapered potentiometer.

TEMPERATURE COEFFICIENT

A constant specifying the amount of change in the value of a quantity for a given change in temperature.

TERMINAL

An external contact point on an electronic device.

TERMINAL EQUIVALENCY

A condition that occurs when two circuits produce the same load voltage and load current where the same value of load resistance is connected to either circuit.

TESLA

The unit of flux density.

THERMISTOR

A type of variable resistor that is temperature-sensitive.

THEVENINS THEOREM

A circuit theorem that provides for reducing any resistive circuit to a single equivalent voltage source in series with an equivalent resistance.

THYRISTOR

A class of four-layer semiconductor devices.

TRAILING EDGE

The second step or transition of a pulse.

TRANSFORMER

A device formed by two or more windings and are magnetically coupled to each other and providing a transfer of power electromagnetically from one winding to another.

TRANSIENT

A temporary passing conductor in a circuit; a sudden or temporary change in circuit conditions.

TRANSISTOR

A semiconductor device used for amplification and switching applications in electronic circuits.

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TRIANGULAR WAVE

A type of electrical waveform that consists of two ramps.

TRIGGER

The activating mechanism of some electronic devices or instruments.

TRIMMER

Small variable capacitor.

TURNS RATIO

The ratio of turns in the secondary winding to turns in the primary winding.

UNIJUNCTION TRANSISTOR (UJT)

A type of transistor consisting of an emitter and two bases.

UNITY GAIN

A gain of 1.

VALENCE

Related to the outer shell or orbit of an atom.

VALENCE ELCTRON

An electron that is present in the outermost shell of an atom.

VARACTOR

A diode that is used as a voltage-variable capacitor.

VOLT

The unit of voltage or electromotive force.

VOLTAGE

The amount of energy available to move a certain number of electrons from one point to another in an electric circuit.

VOLTAGE DROP

The potential difference in voltage between two points when there is a drop in energy level due to resistance.

VOLTAGE GAIN

The ratio of output voltage to input voltage.

VOLTAGE REGULATION

The process of maintaining an essentially constant output voltage over variations in input voltage or load.

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VOLTAGE-AMPERE REACTIVE (VAR)

The unit of reactive power.

VOLTMETER

An instrument used to measure voltage.

WATT (W)

The unit of power.

WATTS LAW

A law that states the relationship of power to current, voltage, and resistance.

WAVEFORM

The pattern of variations of a voltage or current showing how the quantity changes with time.

WEBER

The unit of magnetic flux.

WINDING

The loops or turns of wire in an inductor.

WIPER

The sliding contact in a potentiometer.

ZENER DIODE

A type of diode that operates in reverse breakdown (called zener breakdown) to provide voltage regulation.