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( 42)


mocouples, are classed as generators.
electric osmosis See ELECTRO-OSMOSIS.
electric glow The light (usually pale blue) that oc-
electric piano See ELECTRONIC PIANO.
casionally accompanies an electric discharge in
electric polarization 1. The orientation of flux
lines in an electric field. 2. The orientation of the
electric guitar A guitar whose acoustic vibrations
electric field component in an electromagnetic
are converted by a transducer to an electrical sig-
nal for amplification.
electric potential See ELECTROSTATIC POTEN-
electric hygrometer An instrument for measuring
humidity in terms of the moisture-sensitive resis-
electric power Symbol, P. Unit, watt. The rate at
tance of a sensor. A relatively simple direct-
which electrical energy is used. Power is energy
current (dc) circuit is used. Compare
per unit time; in the context of electricity, it is ex-
pressed as the product of current and voltage. In
electric hysteresis See ELECTROSTATIC HYS-
terms of heat losses, it is often expressed as I 2R
(current in amperes squared, multiplied by resis-
electrician A professional person who installs and
tance in ohms).
services electrical equipment and wiring.
electric precipitator See DUST PRECIPITATOR.
electric image For solving certain problems in-
electric probe A pin or rod inserted into an elec-
volving electricity, an array of electrical points
trostatic field to sample it, or into an electromag-
forming an image of certain other electrical
netic field to sample its electric component. See,
for example, WAVEGUIDE PROBE. Compare
electricity 1. Phenomena resulting from the exis-
tence of stationary or moving electric charge car-
electric radiation 1. The radiation of energy by
riers, such as electrons, holes, and ions. 2. A
means of electric waves. 2. The energy so radiated.
branch of physics concerned with phenomena re-
electric recording Inkless recording on paper by
sulting from the existence of stationary or moving
direct use of an electric current. The two principal
charge carriers. 3. Electrical energy or power. 4.
types are: (1) A current-carrying stylus burns
The voltage existing at utility outlets. In the North
away (in a fine line) the metallic coating of the
America, this is nominally an alternating-current
recording paper, exposing the dark underlying
(ac) voltage of 117 or 234 V at 60 Hz.
layer. (2) A stylus delivers current that produces
electric lamp An electric-powered device used pri-
a line by means of electrolysis in a special paper
marily as a source of light. Common types are
arc, incandescent, and fluorescent.
electric light 1. Visible light produced by means of
electric reset See ELECTRICAL RESET.
electricity. 2. Electric lamp.
electric residue A residual electric charge, such as
electric lines of flux Lines of flux associated with
might remain on a capacitor after it has been in-
an electric charge and constituting the charge™s
completely discharged.
electric field.
236 electric rings • electroballistics

electric rings Colored rings formed on a plate by To
the electrolytic deposition of substances, such as osc.
copper and some peroxides.
electric screen See ELECTROSTATIC SCREEN.
electric shield See ELECTROSTATIC SCREEN.
electric shock A physiological reaction caused by Variable
the passage of electric current through living tis- tuning
sue. When slight, it is characterized by tingling
sensations and involuntary contractions of the
muscles; a severe shock can cause paralysis, un-
consciousness, heart fibrillation, and/or burns. If
Varactor Tuned circuit
heart fibrillation occurs or if burns are severe,
death can result.
electric spark A momentary, luminous discharge electric tuning
of electricity in the space between two electrodes.
Compare ARC, 1.
electric steel Steel that has been processed in an electric vector In an electromagnetic field, the
electric furnace. vector representing the electric component. It is

electric strain See DIELECTRIC STRAIN. perpendicular to the magnetic vector.
electric strain gauge A device for detecting the electric volume density The ratio of the electric

strain that a certain stress produces in a body. charge in a space to the volume of the space.
Typically, such a gauge consists of one or more Compare ELECTRIC SURFACE DENSITY.
fine insulated wires cemented to the surface un- electric watch A small timepiece driven by a tiny,
der test. As the surface becomes strained, the self-contained electrochemical cell that drives an
wire stretches, undergoing a change in electrical electrical escapement or other stepping mecha-
resistance that is proportional to the change in nism. Compare ELECTRONIC WATCH.
strain. electric wave See ELECTROMAGNETIC WAVES.
electric strength See DIELECTRIC STRENGTH. electric-wave filter A circuit or device for separat-
electric stress See DIELECTRIC STRESS. ing signals of one frequency from those of other

electric stroboscope See ELECTRONIC STROBO- frequencies.
SCOPE. electric whirl See ELECTRIC VANE.
electric surface density The ratio of the electric electric wind 1. Air currents set up by electrons
charge on a surface to the area of the surface. escaping from the sharp point of a high-voltage
Compare ELECTRIC VOLUME DENSITY. electrode. 2. The outward-rushing plasma (solar
electric tachometer See ELECTRONIC TACHO- wind) ejected by the sun and traveling through
METER. space.
electric telemeter A device that sends metered electrification 1. Generating an electric charge in
data over a wire transmission line to a remote a body, as in charging a glass rod by rubbing it
point for monitoring. with a silk cloth. 2. Providing electric service (e.g.,
electric thermometer See ELECTRONIC THER- RURAL ELECTRIFICATION). 3. The conversion of
MOMETER. a system from purely mechanical to electrical or
electric transcription See ELECTRICAL TRAN- electromechanical.
SCRIPTION. electroacoustic Pertaining to devices and systems
electric transducer A transducer that responds to that exhibit both electrical and acoustic effects.
non-electric energy, then delivers a proportional For example, speakers and microphones are elec-
electric current or voltage to another circuit. troacoustic devices.
electric tuning A means of adjusting the fre- electroacoustic device A device that transfers en-
quency of a receiver, transmitter, transceiver, or ergy by converting it from electrical to acoustic
oscillator, without the use of mechanical devices. form or vice-versa.
An example is the use of a varactor diode, whose electroacoustic transducer A transducer that
capacitance varies with voltage. converts sound vibrations into electrical pulsa-
electric utilities The power companies that sup- tions or, conversely, one that converts electricity
ply electric current for industrial and consumer into sound.
use. electroanalysis Chemical analysis performed by
electric vane A small demonstration device con- electrolytic methods.
sisting of a rotor having several spokes terminat- electroanesthesia Anesthesia produced by an
ing in points. The rotor is mounted on a pivot electric current going through some part of the
bearing and, when it is connected to a source of body.
high voltage, spins from the force of electricity electroballistics A branch of physics concerned
escaping from the points into the surrounding with the electrical or electronic measurement of
air. the velocities and trajectories of projectiles.

electrobath • electrode efficiency

electrobath A solution in which ELECTRO- switches the device on, initiating ion current from
PHORESIS or ELECTROPLATING is done. anode to cathode through the liquid.
electrobiology Biology concerned with electrical electrochemical transducer A transducer that
phenomena in living organisms. converts chemical changes into electrical quanti-
electrobioscopy The examination of a body for vi- ties, or vice versa. Examples: soil-acidity probe
ability by inducing muscular contractions with and electrolytic elapsed-time meter.
an electrical impulse. electrochemistry The branch of chemistry, over-
electrocapillarity The production of capillary ef- lapping with physics, concerned with chemical
fects by means of electricity. See, for example, action arising from the effect of electricity on sub-
CAPILLARY ELECTROMETER. stances, and electrical effects produced by chem-
electrocardiogram Abbreviation, ECG or EKG. A ical action.
record made by an electrocardiograph of the electrochromic display A display that operates by
changes in potential caused by the heartbeat; means of electric fields, which control the light-
used as a diagnostic aid. transmission and light-reflection characteristics
electrocardiograph An instrument that records in different regions of the material.
changes in electrical potential caused by the electrochronometer A precision electric or elec-
heartbeat. tronic clock. Also see ELECTRIC CLOCK and
electrocardiophonograph A medical instrument ELECTRONIC CLOCK.
that detects and records the impulses of the electrocoagulation Use of a high-frequency alter-
heart. nating current to solidify tissue, as in arresting
electrocatalysis Catalytic action produced by bleeding.
electricity (see CATALYSIS). electrocorticogram See ELECTROENCEPHALO-
electrocautery 1. In medicine, a cauterizing in- GRAM.
strument consisting essentially of a platinum electroculture Acceleration or modification of
wire (at the tip of an insulated probe) that is plant growth through the application of electricity
heated by an electric current. Also see ELECTRIC to plants, seeds, or soil.
NEEDLE. 2. Cauterizing with an electrocautery. electrocution 1. Death resulting from electric
electrochemical deterioration An electrochemi- shock. 2. An electric shock inflicted for the purpose
cal reaction that results in the permanent or tem- of causing death (e.g., in an ELECTRIC CHAIR).
porary failure of a device. electrode A body, point, or terminal in a device or
electrochemical diffused-collector transistor A circuit that delivers electricity, or to which elec-
high-current pnp transistor in which metal has tricity is applied. A positive electrode is usually
replaced the etched-away mass of p material, an ANODE; a negative electrode is usually a
providing a built-in heatsink. CATHODE.
electrochemical equivalent In electrolysis or elec- electrode admittance The admittance encoun-
troplating, a constant (Z ) for the metal in plates. tered by current flowing through an electrode; the
For a given metal, Z is the mass (in grams) of the property is entirely that of the electrode and is the
metal deposited by 1 coulomb of electricity. reciprocal of ELECTRODE IMPEDANCE. Consists
electrochemical junction transistor See SUR- of a real-number component (ELECTRODE
electrochemical measurements 1. Measurements component that is 90 degrees out of phase
made on chemical substances with electrical in- (ELECTRODE SUSCEPTANCE).
struments to determine such factors as conduc- electrode capacitance The capacitance between
tivity, pH, dielectric strength, dielectric constant, an electrode and a reference body, such as
etc. 2. Measurements of electrical or electronic ground or another electrode.
phenomena in terms of electrochemical response electrode characteristic The mathematical func-
(e.g., current drain in terms of weight of plated tion or graph of electrode current versus elec-
metal, or voltage in terms of gas breakdown). trode voltage.
electrochemical polarization The disabling of a electrode conductance The conductance encoun-
primary cell caused by gas products deposited tered by current flowing through an electrode; the
around or on one of the electrodes. property is entirely that of the electrode and is the
electrochemical recording See ELECTRIC RE- reciprocal of ELECTRODE RESISTANCE.
CORDING. electrode current Current entering or leaving an
electrochemical reduction Extracting a metal electrode.
from a compound by means of electrolysis. electrode dark current See DARK CURRENT.
electrochemical series See ELECTROMOTIVE electrode dissipation The power lost in the form
SERIES. of heat in an electrode.
electrochemical switch A static, ionic alternat- electrode drop Voltage drop resulting from ELEC-
ing-current (ac) switch consisting of an anode, TRODE RESISTANCE.
cathode, and a control electrode, all immersed in electrode efficiency In an electrolytic cell, the ra-
an electrolyte. A positive control-electrode voltage tio of the yield of metal deposited to the maximum
238 electrode efficiency • electrokinetics

possible theoretical yield. This value ranges be- electrodynamics The branch of physics con-
tween 0 and 1 (0 percent and 100 percent). cerned with moving electric charge carriers,
electrode impedance The impedance encountered such as electrons, holes, and ions. Also con-
by alternating current flowing through an elec- cerned with the interaction of electrical and me-
trode; the property is entirely that of the electrode chanical phenomena. Important in the design
and is the reciprocal of ELECTRODE ADMIT- and manufacture of devices, such as motors and
TANCE. Consists of a real-number component generators.
(ELECTRODE RESISTANCE) and an imaginary- electrodynamic speaker See DYNAMIC SPEAKER.
number component that is 90 degrees out of electrodynamism See ELECTRODYNAMICS.
phase (ELECTRODE REACTANCE). electrodynamometer An indicating meter whose
electrodeless discharge Discharge in a gas tube movable coil rotates between two stationary coils.
that is not directly connected to a power source. All three coils are connected in series, and the
A familiar example is the glow of a neon lamp held magnetic fields of the two stationary coils are ad-
in a strong radio-frequency (RF) electromagnetic ditive. This meter produces a positive indication
field. for alternating current (ac), as well as for direct
electrodeposit 1. To deposit a substance by elec- current (dc). Can be adapted for use as an amme-
trical action. Also see ELECTROPHORESIS and ter, voltmeter, or wattmeter.
ELECTROPLATING. 2. A deposit that is formed electroencephalogram Abbreviation, EEG. A
on an electrode by electrophoresis or electroplat- record made by an ELECTROENCEPHALO-
ing. GRAPH, showing changes in electric potential re-
electrodeposition The electrical application of a sulting from bioelectric action in the brain. The
layer of one material (such as a metal) on the sur- record is used as a diagnostic aid.
face of another (the substrate) (e.g., electroplat- electroencephalograph An instrument that pro-
ing, evaporation, and sputtering). duces a record of voltage changes resulting from
electrode potential See ELECTRODE VOLTAGE. the brain™s bioelectricity.
electrode reactance The imaginary-number com- electroencephaloscope A type of oscilloscope
ponent of ELECTRODE IMPEDANCE. used to pick up, amplify, and display changes in
electrode resistance The resistance encountered potential caused by the brain™s bioelectric action.
by current flowing through an electrode; the electroextraction Extracting a substance from a
property is entirely that of the electrode and is the mixture (e.g., a metal from an ore) by an electrical
reciprocal of ELECTRODE CONDUCTANCE. process, such as electrolysis.
electrodermography A method of monitoring electroform 1. To precondition a material or de-
the functions of the human body by measuring vice (e.g., a semiconductor junction) by passing a
the resistance between two electrodes placed on current through it for a specified period. 2. To
the surface of the skin. form articles by electrodepositing material on a
electrode susceptance The imaginary-number mold or core.
component of ELECTRODE ADMITTANCE. electrogalvanized Electroplated with zinc.
electrode voltage The voltage between an elec- electrogastrogram A recording of the electrical im-
trode and a reference point, such as ground or pulses and other functions of the stomach, for
another electrode. medical diagnostic purposes.
electrodiagnosis 1. The diagnosis of a disease or electrograph 1. A picture transmitting or receiving
disorder through the use of electromedical in- device (see FACSIMILE RECEIVER and FACSIM-
struments. 2. Troubleshooting the electrical por- ILE TRANSMITTER). 2. A device used for the elec-
tion of electromechanical equipment. trolytic etching or transfer of designs.
electrodialysis See ELECTRO-OSMOSIS. electrographic recording A method of producing
electrodissolution Dissolving a constituent sub- a visible pattern or record, using electrodes to
stance of an immersed electrode by means of create discharge through an insulating material.
electrolysis. electrographite Synthetic graphite prepared by
electrodynamic Pertaining to electricity in motion heating carbon in an electric furnace.
(i.e., current flow and its accompanying electric electrojet A region of high current concentration
and magnetic fields). in the sky near bright auroral displays or along
electrodynamic braking Stopping a tape-deck the magnetic equator.
motor quickly by applying a braking voltage. In electrokinetic energy The energy of electric
this method, direct braking current flows through charge carriers in motion; a form of kinetic en-
the shaded-pole alternating-current (ac) reel ergy. The current in a wire (a flow of electrons) is
motor. a common manifestation of this form of energy.
electrodynamic instrument See ELECTRODY- Compare ELECTROSTATIC ENERGY.
NAMOMETER. electrokinetics A branch of electricity concerned
electrodynamic loudspeaker See DYNAMIC with (1) the behavior of moving charged parti-
SPEAKER. cles (such as ions and molecules) and bodies in
electrokinetics • electrolytic elapsed-time meter

motion, and (2) the generation of static charges electrolytic capacitor A component that is man-
by moving liquids or solids in contact with each ufactured by rolling up aluminum foil strips
other. separated by paper saturated with electrolyte.
electroless process Plating a metal from a When a polarized voltage is applied, the alu-
solution of one of its salts without using elec- minum oxidizes. The oxide layer forms the di-
tricity. electric for the capacitor. The layer is extremely
electroluminescence The ability of certain phos- thin, producing high capacitance per unit vol-
phors to emit light continuously when an alter- ume. This type of capacitor must be connected
nating-current (ac) voltage is applied to them. with the proper polarity in a circuit. The compo-
electroluminescent cell A device for generating nent can have values up to thousands of micro-
light by electroluminescence. It consists of a lu- farads, and some units can handle thousands of
minescent-phosphor layer and two transparent volts. They are used in audio circuits and in
metal films. An alternating-current (ac) voltage power supplies. Compare CERAMIC CAPACI-
applied between the films causes the phosphor to TOR, MICA CAPACITOR, PAPER CAPACITOR,
glow through the transparent metal. PLASTIC-FILM CAPACITOR, TANTALUM
Light rays
To ac
Glass plate voltage
metal coat Electrolyte
Glass plate
Phosphor +
aluminum foil

electrolytic capacitor

electrolytic cell An electrochemical device con-
taining an electrolyte and at least two elec-
Clear trodes. Included in this category are voltaic
conductive cells, electrolytic capacitors, and electrolytic re-
electrodes sistors.
electrolytic conduction Electric current flowing
electroluminescent cell through an electrolyte, an action characterized by
(1) positive electrolyte ions migrating to the
negative electrode, where they acquire electrons;
electroluminescent lamp A lamp using one or
(2) negative ions migrating to the positive elec-
more electroluminescent panels.
trode, where they lose electrons; and (3) current
electroluminescent panel A panel that forms a
flow in the external circuit, which consists of con-
complete electroluminescent cell. It delivers low-
ventional electron flow (current in the electrolyte
intensity visible light when an alternating-
is a movement of ions).
current (ac) voltage is applied to it. Available in
electrolytic conductivity Conductance of an elec-
various sizes and shapes.
trolyte. It is the conductance of a cube of the elec-
electrolysis 1. The action whereby a current pass-
trolyte, measuring one centimeter along each
ing through a conductive solution (electrolyte)
edge, at a specified temperature.
produces a chemical change in the solution and
electrolytic corrosion Corrosion caused by an ap-
the electrodes. 2. An electrical method of destroy-
plied voltage, or that is accelerated by the voltage.
ing hair roots.
electrolyte A substance that ionizes in solution.
electrolytic current meter See VOLTAMMETER.
Electrolytes conduct electricity; in batteries, they
electrolytic dissociation See DISSOCIATION.
are instrumental in producing electricity by
electrolytic elapsed-time meter An instrument
chemical action.
that indicates the time that equipment has been
electrolytic 1. Containing an electrolyte sub-
in operation in terms of the amount of metal
240 electrolytic elapsed-time meter • electromagnetic energy conversion

electroplated on the cathode of an electrolytic radiotelephony, facsimile, and television. 2. Elec-
cell by energy consumed during the period. tronic communication via electromagnetic fields
electrolytic gas A gas produced by electrolysis. (i.e., radio communication).
Examples are hydrogen (H) and oxygen (O), gen- electromagnetic compatibility 1. The ability of a
erated in a ratio of two to one, by the electrolysis set of electronic devices to work together without
of water (H2O). being adversely affected by each other™s electro-
electrolytic iron Very pure iron obtained by elec- magnetic fields. 2. In radio communication, the
trolytic refining. relative immunity of a device or devices to the ef-
electrolytic polarization In electrolysis, the ten- fects of electromagnetic fields.
dency for the products to recombine. In an elec- electromagnetic complex A system that produces
trolytic cell, this effect interferes with the electromagnetic radiation.
performance of the cell, reducing the voltage. electromagnetic component 1. The magnetic
electrolytic potential The difference of potential component of an electromagnetic wave, which is
that appears between a metal electrode in an perpendicular to the electrostatic component,
electrolyte and the electrolyte immediately and can be thought of as the wave™s current
surrounding it. Also see ELECTROMOTIVE component. 2. A device operated by electro-
SERIES. magnetism, such as a coil-type relay or a current-
electrolytic recorder A data recorder that uses a operated field magnet.
paper impregnated with a chemical that turns electromagnetic consonance An effect that takes
dark when an electric current passes through the place when two antenna elements, both having
paper from the point of a stylus. identical or nearly identical resonant frequencies,
electrolytic rectifier A rectifier consisting of an are in close proximity. If one antenna is fed with
aluminum electrode and a lead or carbon elec- energy at its resonant frequency, currents will be
trode in a solution of borax or sodium bicarbon- induced in the other antenna, and it, too, will ra-
ate, or in a solution of ammonium citrate, diate. Parasitic arrays, such as the Yagi antenna
ammonium phosphate, and potassium citrate. and the quad antenna, operate on this principle.
Also called chemical rectifier. See RESONANCE.
electrolytic refining Extracting or purifying met- electromagnetic constant 1. Symbol, c. The prop-
als by electrolysis. agation speed of electromagnetic waves in a vac-
electrolytic resistor An emergency resistor made uum, approximately equal to 299,792 kilometers
by immersing two wire leads in an electrolyte; the per second or 186,282 miles per second. Also
weaker the solution, the higher the resistance. called SPEED OF LIGHT and VELOCITY OF
electrolytic switch See ELECTROCHEMICAL LIGHT. 2. The propagation speed of electromag-
SWITCH. netic waves in a particular medium. Equal to vc,
electrolyze To subject something to electrolytic where v is the VELOCITY FACTOR of the
action. medium, and c is the speed of electromagnetic
electrolyzer A cell used in the production of vari- waves in a vacuum (299,792 kilometers per sec-
ous materials by electrolysis. See, for example, ond or 186,282 miles per second).
electromagnet 1. A coil of insulated wire wound electromagnetic crack detector An instrument
around an iron or steel cylinder, intended for use that uses electromagnetic fields to find cracks in
as a magnet. When current flows through the iron or steel.
coil, a magnetic field develops, in effect rendering electromagnetic CRT A cathode-ray tube using
the cylinder a strong bar magnet. 2. Any device electromagnetic deflection.
that exhibits magnetism only while an electric electromagnetic cylinder See SOLENOID.
current flows through it. electromagnetic deflection In a television picture
electromagnetic Exhibiting both electric and tube and some oscilloscopes, deflection of the
magnetic properties (e.g., an electromagnetic electron beam by the magnetic fields of external
wave). horizontal- and vertical-deflection coils. Compare
electromagnetic attraction 1. The attraction of ELECTROSTATIC DEFLECTION.
iron or steel to an electromagnet. 2. The attrac- electromagnetic deflection coil See DEFLEC-
tion of an electromagnetic pole to the opposite TION COILS.
pole of another electromagnet. A unit pole at- electromagnetic delay line See DELAY LINE.
tracts another unit pole 1 centimeter away with a electromagnetic energy Energy in the form of
force of 1 dyne or 10-5 newton. Compare ELEC- electric and magnetic fields. A radio wave travel-
TROMAGNETIC REPULSION. ing through space, for example, has electric and
electromagnetic communication 1. Any form of magnetic components, between which energy os-
communication using a combination of electric cillates.
and magnetic phenomena. Examples include electromagnetic energy conversion The conver-
wire telegraphy, wire telephony, radiotelegraphy, sion of electrical energy into mechanical work
electromagnetic energy conversion • electromagnetic microphone

and vice versa, through the intermediary of an Lines of force bend
electromagnetic field. electron streams
Control grid inward so that they
electromagnetic environment A region in which
converge at the
electric and magnetic fields are present.
electromagnetic field A combination of alternat-
ing electric and magnetic fields. The electric lines
of flux are perpendicular to the magnetic lines of
flux at every point in space. The field propagates
in a direction perpendicular to both the electric
and magnetic lines of flux. The frequency of oscil- Cross section of
lation can range from a fraction of one Hz to many focusing coil
quadrillions of Hz. In order from longest wave-
length (lowest frequency) to shortest wavelength electromagnetic focusing
(highest frequency), effects of this type include ra-
dio waves, infrared, visible light, ultraviolet,
X rays, and gamma rays.

Electric field
10’12 Gamma rays
10’10 X rays
10’8 Ultraviolet rays
Magnetic 10’6 Infrared
10’4 Microwaves
10’2 FM broadcast short waves
AM broadcast
10 2
10 4
10 6 60 Hz alternating current
10 8

electromagnetic frequency spectrum
of propagation
electromagnetic field electromagnetic inertia The tendency for the cur-
rent in a circuit to lag the voltage at high fre-
electromagnetic flux The magnetic field sur- electromagnetic interference Abbreviation, EMI.
rounding a coil or conductor carrying an electric A phenomenon in which electronic devices upset
current. each other™s operation. Computers, television re-
electromagnetic focusing In a television picture ceivers, telephone sets, high-fidelity sound
tube, electron-beam focusing obtained by varying equipment, and certain medical devices can
the direct current flowing through an external malfunction because of strong radio-frequency
focusing coil. fields such as those from a nearby broadcast
electromagnetic force The force that causes a transmitter. The EMI is usually the result of
conductor to be displaced from its position in a improper or ineffective shielding in the affected
magnetic field when it conducts current. device or system.
electromagnetic frequency spectrum The fre- electromagnetic lens A coil or coil system whose
quency range of electromagnetic fields including magnetic field causes an electron beam passing
radio waves, infrared, visible light, ultraviolet, through it to converge or diverge as a light beam
X rays, and gamma rays. Ranges from a fraction does in passing through an optical lens. Compare
of one Hz to many quadrillions of Hz. ELECTROSTATIC LENS. Also see ELECTROMAG-
electromagnetic horn radiator A horn used to ra- NETIC FOCUSING.
diate microwave energy. Also see HORN AN- electromagnetic mass The mass that a moving
TENNA. electric charge is thought to possess.
electromagnetic induction Inducing a voltage in electromagnetic microphone A microphone in
a circuit or conductor by causing alternating which sound energy is converted into proportionate
current to flow in another nearby circuit or con- electrical energy by electromagnetism. Common
242 electromagnetic microphone • electromagnetizer

examples are the dynamic microphone and veloc- component. 2. A grounded partition, metal sheet,
ity microphone. wire braid, or other barrier that prevents electro-
electromagnetic mirror A reflector of electromag- magnetic fields from passing through. Commonly
netic waves (e.g., antenna elements, ionospheric used in electronic equipment to prevent ELEC-
layers, buildings, and hills). TROMAGNETIC INTERFERENCE. Also used in
electromagnetic momentum The momentum of a COAXIAL CABLE to confine electromagnetic
moving electric charge, comparable to that of fields to the transmission line.
matter in motion. Electromagnetic momentum is electromagnetic shielding The use of an ELEC-
the product of electromagnetic mass and charge TROMAGNETIC SHIELD to prevent undesired in-
velocity. teraction among electrical and electronic devices
electromagnetic oscillograph 1. An electrome- and systems.
chanical data recorder for tracing the waveform electromagnetic spectrum See ELECTROMAG-
or variations of a signal. 2. See ELECTROME- NETIC FREQUENCY SPECTRUM and ELECTRO-
electromagnetic oscilloscope 1. An oscilloscope electromagnetic switch 1. A switch actuated by
using electromagnetic deflection. 2. See ELEC- magnetism produced by control current flowing
TROMECHANICAL OSCILLOSCOPE. through a coil wound on an iron core. 2. See
electromagnetic pump A device used for moving ELECTROMECHANICAL RELAY.
conducting or semiconducting fluids. When a electromagnetic theory of light The theory that
current is passed through the fluid, a force is ex- light consists of electromagnetic waves that are
erted on the molecules of the fluid because of the similar to radio waves, but of shorter wavelength.
magnetic field set up by the current. electromagnetic tube A cathode-ray tube using
electromagnetic pulse Abbreviation, EMP. 1. A electromagnetic deflection (e.g., a television pic-
broadband electromagnetic field emitted in a ture tube).
short, intense burst from a lightning stroke or electromagnetic unit Abbreviation, emu. A unit
nuclear explosion. This field can disrupt the op- of measure in the electromagnetic system of
eration of, and (in some cases) cause damage to, CENTIMETER-GRAM-SECOND (cgs) units.
electrical and electronic apparatus. 2. In electro- electromagnetic vibrator See INTERRUPTER.
magnetic induction, the displacement of an elec- electromagnetic wavelength spectrum The
tron in a conductor by the magnetic field. wavelength range of electromagnetic fields, in-
electromagnetic radiation The propagation of cluding radio waves, infrared, visible light, ultra-
electromagnetic fields through space; it normally violet, X rays, and gamma rays. It ranges from
occurs at approximately 299,792 kilometers per many kilometers to a tiny fraction of one millime-
second or 186,282 miles per second. ter.
electromagnetic reaction The reaction between electromagnetic-wave polarization The orienta-
magnetic fields. Also see ELECTROMAGNETIC tion of the electric flux lines in an electromagnetic
ATTRACTION and ELECTROMAGNETIC REPUL- (EM) field, especially a field propagating through
SION. space. The polarization is generally parallel with
electromagnetic reconnaissance In military ap- the active element of a radio transmitting or re-
plications, the use of electromagnetic apparatus ceiving antenna. Thus, a vertical antenna radi-
to detect potential enemy activity in a certain ge- ates and receives fields with vertical polarization,
ographic region. and a horizontal antenna radiates and receives
electromagnetic relay See ELECTROMECHANI- fields having horizontal polarization. Some anten-
CAL RELAY. nas radiate and receive an EM field whose polar-
electromagnetic repulsion The repulsion of a pole ization continually and rapidly rotates. This is
of an electromagnet by the pole of another elec- elliptical polarization. If the rate of rotation is con-
tromagnet (north pole opposing north pole, south stant, it is circular polarization.
opposing south). Compare ELECTROMAGNETIC electromagnetic waves Waves produced in a con-
ATTRACTION. ductor or in space by the acceleration or oscilla-
electromagnetics A branch of physics concerned tion of electric charge carriers. Such waves have
with the theory and application of electromag- an electric and a magnetic component acting at
netism. right angles to each other. The waves propagate
electromagnetic screen See ELECTROMAG- at right angles to both the electric and magnetic
NETIC SHIELD. flux lines.
electromagnetic shield 1. A partition, can, or box electromagnetism 1. Magnetism resulting from
made of magnetic material (iron, steel, or special the movement of electric charge carriers (e.g., the
alloy) enclosing a magnetic component. The magnetic field surrounding a coil of wire carrying
magnetic flux generated by the component is con- an electric current). 2. See ELECTROMAGNET-
fined by the shield, thus preventing interference ICS.
with external components. Likewise, external electromagnetizer A magnetizer using continuous
magnetic fields are prevented from reaching the direct current (dc) as the magnetic-field source.
electromechanical • electromigration

electromechanical Descriptive of any device that contact. When control current flows through the
converts energy from electrical to mechanical coil, it becomes magnetized and attracts the ar-
form or vice-versa. Examples are the motor and mature, closing the movable contact against a
the generator. stationary one.
electromechanical amplifier An amplifier that
converts an electrical input signal into mechani-
cal motion (vibratory or rotary), which it then Switched
converts back into an electrical output signal of terminals Movable contact
higher current, voltage, or power.
electromechanical chopper A vibrator-type inter-
Fixed contact
rupter used primarily to chop direct current, con-
verting it into a square-wave signal, whose
Actuating Iron-core coil
amplitude is proportional to current strength.
current (electromagnetic)
Also see CHOPPER.
electromechanical counter A device that indi-
cates the number of pulses that have been ap-
electromechanical relay
plied to it. Typically, it has a series of dials”each
capable of displaying the numerals 0 to 9 in se-
electromechanical timer A device for automati-
quence, one for each decade in the count. The di-
cally timing a process or an observed event. Most
als are geared together, the train being operated
such timers are based on an accurate clock (elec-
by the stepping action of an electromagnetic es-
tric or spring driven) that opens or closes
capement. Compare ELECTRONIC COUNTER.
contacts at predetermined instants. Compare
electromechanical energy The energy stored by
an inductor or capacitor in an electromechanical
electromechanical transducer A transducer that
translates mechanical signals directly into elec-
electromechanical filter See ULTRASONIC FIL-
trical ones or vice versa, without the intermediary
TER, 1.
of active devices, such as transistors or inte-
electromechanical flip-flop See BISTABLE RELAY.
grated circuits.
electromechanical frequency meter A usually di-
electromechanical valve A usually poppet-type
rect-reading instrument for measuring frequency
valve for gases or liquids. The valve is operated by
in the lower and middle portions of the audio
electromagnetic action and is often aided by an
spectrum. It works via the mechanical motion re-
electronic (servo) circuit.
sulting from the applied signal. The two varieties
electromechanics The theory and application of
are the movable-iron type and the reed type.
electromechanical devices.
electromechanical modulator See CHOPPER.
electromedical engineering The branch of elec-
electromechanical oscillator An oscillator con-
tronics engineering concerned with the theory,
sisting of an electromechanical amplifier provided
design, and application of electronic equipment
with regenerative feedback.
for medical diagnosis or treatment.
electromechanical oscilloscope A galvanometer-
electromedical equipment Electrical or electronic
type instrument for displaying a varying or alter-
equipment used in medical diagnosis or treat-
nating current or voltage. The signal is applied to
a meter movement having a movable coil, which
electromerism Ionization in gases.
swings or vibrates in response to the signal. A
electrometallurgy The branch of metallurgy con-
tiny mirror cemented to the coil reflects a beam of
cerned with the use of electricity (especially in
light to a rotating mirror that sweeps the beam
electrolysis) to separate or purify metals or to fur-
across a translucent screen on which the image is
nish heat for metallurgical processes.
electrometer A specially designed, highly sensitive
electromechanical recorder An instrument in
electronic voltmeter used to measure extremely
which a pen or stylus is moved on a sheet of pa-
low voltages and, indirectly, extremely low cur-
per by the varying signal current or voltage being
rents. It is sometimes used as a galvanometer.
electrometer amplifier A stable low-noise amplifier
electromechanical rectifier A rectifier in which a
for increasing the sensitivity of an electrometer.
moving part, such as a vibrating reed or rotating
electrometry The science of electrical measure-
commutator-slip-ring unit, is driven by alternat-
ing current (ac) to close the circuit during positive
electromigration The movement of atoms in a
or negative ac half-cycles, thus rectifying the ac.
substance from one place to another, because of
interaction between electrons and ions in the
presence of electric currents. This effect can
electromechanical relay An electromagnetic
cause the eventual deterioration of certain semi-
switch consisting of a multiturn coil wound on an
conductor devices.
iron core near an armature with a movable end
244 electromotion • electron gun

electromotion Motion produced by electric deflects the electron beam in a cathode-ray tube
charges or electrons. over a distance that is proportional to field inten-
electromotive force Abbreviation, emf. Electrical sity.
pressure, the potential that causes charge carri- electron-beam recording In digital computer op-
ers to move through a substance or circuit. See erations, a technique whereby the output of a
VOLTAGE. computer is recorded on microfilm by an electron
electromotive series A list of metals arranged ac- beam.
cording to the potential between the surface of electron-beam scanning tube A tube in which an
the metals and an electrolyte into which they are electron beam strikes a sensitized screen to pro-
immersed. Some metals acquire a positive poten- duce a spot of light, which is deflected electrically
tial (with respect to hydrogen, for which the po- or magnetically across a screen. Examples are os-
tential is zero) and others, a negative potential. cilloscope tubes, storage tubes, and television
electromotor A generator or motor, depending picture tubes.
upon the context in which the term is used. electron-beam tube Electron tubes (such as
electromyogram The record produced by an beam-power tubes, klystrons, oscilloscope tubes,
ELECTROMYOGRAPH. and television picture tubes), in which an elec-
electromyograph An instrument for detecting, tron beam is generated and controlled.
measuring, and analyzing the weak electrical electron-beam welding A method of welding in
currents generated by muscular activity. which an electron beam is focused on the work-
electromyography The monitoring and analysis of piece to heat it.
the electrical activity of human muscles. electron-bombarded semiconductor A semicon-
electron The subatomic particle that carries the ductor wafer, plate, or junction that is acted on
unit negative charge of electricity. The electron by an electron beam; it alters the resistance of the
has a mass of 9.109 — 10“31 kilogram and carries semiconductor to control the current in an exter-
a charge of 1.602 — 10“19 coulomb. nal circuit.
electron acceleration See ELECTRON MOTION, 2. electron-bombarded semiconductor amplifier
electronarcosis Loss of consciousness caused by See EBS AMPLIFIER.
passing a weak current through the brain. Useful electron bunching See BUNCHING.
in treating certain mental disorders, the process electron charge See ELEMENTARY CHARGE.
is somewhat similar to ELECTROSHOCK. electron cloud A mass of free electrons.
electron attachment The bonding of an electron electron diffraction Diffraction that occurs when
to a neutral atom to form a negative ion. Also see a beam of electrons passes through a crystal ma-
ANION and ION. terial. Fast-moving electrons have wavelike prop-
electron avalanche See AVALANCHE and ELEC- erties; the wavelength depends on the speed of
TRON MULTIPLICATION. the particles. This effect can also occur with
electron band 1. An emission line in the spectrum beams of other particles, such as neutrons, pro-
of an element or compound, caused by the move- tons, or alpha particles.
ment of electrons from higher to lower energy lev- electron drift 1. The movement of an electron
els within the atoms. 2. An absorption line in the from atom to atom in a conductor, as caused by
spectrum of an element or compound, caused by the influence of an applied voltage. 2. In a semi-
the movement of electrons from lower to higher conductor, directed electron movement. Also see
energy levels within the atoms. DRIFT, 1.
electron beam See ELECTRON STREAM, 1. electronegative Having negative electrification or
electron-beam bender Any element that causes polarity (see ELECTRICAL POLARITY). Compare
intentional deflection of the electron stream in a ELECTROPOSITIVE.
cathode-ray tube. electron emission The emission of electrons into
electron-beam focusing Reducing the size of the surrounding space by a material. Depending on
spot produced by the electron beam in a cathode- the material, this effect can be initiated by appli-
ray tube or television picture tube. This is accom- cation of heat, light, torsion, electron impact, a
plished by adjusting the direct-current (dc) bias high-voltage field, and other actions.
voltage on a focusing electrode. electron flow See ELECTRON DRIFT.
electron-beam generator 1. See ELECTRON GUN. electron g-factor A physical constant that ex-
2. A tube, such as a Klystron, in which velocity presses the ratio of electron magnetic moment to
modulation of the electron beam generates ex- the Bohr magneton, and equal to approximately
tremely high radio frequencies. 1.00116. Also called free-electron g-factor.
electron-beam instrument An instrument, such electron-gas binding forces See METALLIC BIND-
as an oscilloscope, based on a cathode-ray tube. ING FORCES.
electron-beam machining Welding or shaping electron-gas bonding See BONDING, 1 and
materials by controlled electron beams. METALLIC BINDING FORCES.
electron-beam magnetometer A magnetometer in electron gun A composite electrode for generating
which the magnetic field under measurement an electron beam (see ELECTRON STREAM, 1) in
electron gun • electronic counter

is manually wired during the experimental phase
a vacuum. In a cathode-ray tube, the gun com-
of product development.
prises a heated cathode, control electrode, accel-
electronic bug 1. A semiautomatic telegraph key
erating electrodes, and a focusing electrode.
that produces dots via an oscillating mechanical
electron-hole pair In a semiconductor, an electron
arm. The operator produces dashes manually.
and a related hole. Each electron in the conduc-
2. A telegraph keying device that automatically
tion band has a counterpart in the valence band,
generates dots and dashes. Also see ELECTRONIC
a vacancy (hole) left by the electron™s moving to
KEY, 1. 3. An undetermined source of problems
the conduction band.
or improper operation in an electronic circuit.
electronic buzzer 1. A mechanical buzzer driven
by a direct-current (dc) amplifier. 2. An oscillator
circuit that produces a sound similar to that of a
mechanical buzzer.
electronic calculating punch A machine that
punches on a card the result of calculations it
has performed on data it has read from another
Valence band punched card.
electronic calculator A fully electronic machine
for performing mathematical calculations. The
simplest machines perform basic arithmetic;
more sophisticated ones can do operations with
trigonometric, logarithmic, hyperbolic, and other
scientific functions. Basic machines are available
in department stores for about five dollars. It is
Electron usually powered via a small cell or battery, or by
a small photovoltaic panel.
electron-hole pair electronic camouflage The use of electronics by a
target craft to minimize or prevent the reflection
of radar echoes.
electronic 1. Descriptive of any component, de- electronic carillon An electronic system that pro-
vice, or system that functions, according to the duces sounds resembling those of a bell carillon.
principles of ELECTRONICS. 2. Pertaining to electronic chime See ELECTRONIC CARILLON.
electrons. electronic circuit An electric circuit containing
electronic adder A circuit (such as an operational active electronic components, such as transistors
amplifier) for performing arithmetic addition. In and integrated circuits, as opposed to a circuit
such a circuit, the output-signal amplitude is the containing only passive electrical components
sum of the input-signal amplitudes. Also see (such as resistors, switches, heating elements,
electronic aid An electronic device or circuit that electronic clock 1. An electric clock whose motor
contributes to the operation of a nonelectronic is driven by a constant-frequency oscillator (crys-
device or system; a pH meter, for example, is an tal or tuning fork type), followed by multivibrators
electronic aid to chemistry. and amplifiers. 2. Any electronic timing circuit
electronics aide See ELECTRONICS TECHNICIAN. that produces pulses at predetermined intervals
electronic attenuator An attenuator in which the for the purpose of regulating the operation of
variable resistor is the output section of an active other circuits, subsystems, or assemblies.
device, such as a transistor. Varying the direct- electronic commutator See COMMUTATOR, 2.
current (dc) bias of the input section varies the electronic conduction A flow of electric current
resistance of the output section. resulting from the movement of electrons among
electronic autopilot A servo system for detecting atoms in a conductor.
and automatically correcting an aircraft™s flight electronic control 1. The science of automatically
path. controlling machines and devices by means of
electronic balance An electronic scale, which uses electronic circuits. 2. A circuit or device that pro-
a sensitive current-measuring device in conjunc- vides automatic electronic control.
tion with a movable tension device. electronic controller A controller (see CON-
electronic brain 1. A high-end computer. 2. A TROLLER, 2) having no moving parts. For auto-
robot controller. 3. A system that possesses or matic operation, such a device often contains a
uses artificial intelligence (AI). circuit that senses control signals, compares
electronic breadboard 1. A thin, usually non- them with a signal standard, and automatically
metallic board or card having prepunched holes adjusts the output control power accordingly.
for the quick assembly of electronic circuits for electronic counter A fully electronic circuit that
test and evaluation. 2. Any circuit prototype that indicates the number of pulses that have been
246 electronic counter • electronic heating

applied to it (see COUNTER, 1). Unlike the elec- electronic differential analyzer See ANALOG
tromechanical counter, the electronic counter DIFFERENTIATOR, DIGITAL DIFFERENTIAL AN-
has no moving parts and is therefore capable of ALYZER, and DIFFERENTIAL ANALYZER.
extremely high-speed, noiseless operation. electronic differentiator A circuit that performs
electronic counter-countermeasures Abbrevia- mathematical differentiation. Also see DIFFER-
tion, ECCM. Military procedures for interfering ENTIATOR, 2.
with a foe™s electronic countermeasures. electronic divider 1. An electronic device for per-
electronic countermeasures Abbreviation, ECM. forming arithmetic division. In a digital computer,
Interference with enemy radio and radar emis- such a divider can be a sequence of flip-flops,
sions by electronic means. Also see JAMMING. each of which produces a single output for every
electronic coupling Coupling via electronic effects two input pulses. In an analog computer, the out-
or devices. put signal amplitude is equal to the quotient of
electronic crowbar A switch that prevents de- two input-signal amplitudes. 2. See FREQUENCY
structive currents from flowing through the com- DIVIDER. 3. A voltage divider using active com-
ponents of a circuit. ponents, rather than resistors.
electronic current meter A current meter that electronic dust precipitator See DUST PRECIPI-
uses an amplifier ahead of an analog or digital in- TATOR.
dicator to provide increased sensitivity. electronic efficiency A quantitative expression for

the effectiveness of an electron beam as a
medium of power transmission. The electronic ef-

ficiency, in percent, is equal to 100Pout/Pin, where
Pout is the (output) power delivered by the beam,
and Pin is the (input) power supplied to the beam.
electronic equivalent of gravity In equations for
the acceleration, velocity, and distance traveled
dc mA
+ for an electron, the factor equal to eF/m, where e
is the electron charge, F is the potential gradient
of field, and m is the electron mass. Also see

electronic flash 1. A device containing a circuit
that uses an electronic flash tube as a light
’ source for photography or other purposes. Also
called photoflash. 2. A bright momentary light
burst produced by the equipment described in 1,
electronic flash tube A tube used to produce bril-
+12 V liant bursts of light in photoflash units, strobo-
scopes, and laser exciters. A flash tube usually
electronic current meter contains xenon gas, which is fired by a high-
voltage pulse.
electronic frequency meter 1. An instrument
electronic data processing Abbreviation, EDP. that gives direct readings of frequency in hertz,
See DATA PROCESSING and ELECTRONIC IN- kilohertz, or megahertz on an analog scale or as a
FORMATION PROCESSING. digital readout. 2. Any device that indicates the
electronic data-processing center Abbreviation, operating frequency of another device, directly or
EDPC. An installation of electronic equipment indirectly, when used for such purpose.
and accessories for processing and storing data, electronic frequency synthesizer An instrument
usually in digital form. Also see DATA PROCESS- that supplies a number of selectable frequencies
ING and ELECTRONIC INFORMATION PRO- derived from one or more internally generated
CESSING. fixed frequencies.
electronic data-processing machine Abbrevia- electronic gas A collection of free electrons whose
tion, EDPM. A device, such as an electronic com- behavior resembles that of a gas.
puter, used in the automatic processing of data, electronic gate 1. A logic gate that operates by
usually in digital form. electronic means. 2. A security system, consist-
electronic data-processing system 1. A unique ing of a mechanical gate controlled electronically.
arrangement of machines for processing data. 2. Similar to an electronic garage door.
The sequence of steps in, and the underlying ra- electronic guitar See ELECTRIC GUITAR.
tionale for, the processing of data by automated electronic heating The production of heat in an
equipment. object via high-frequency energy. The two princi-
electronic deception See DECEPTION and DE- pal methods are dielectric heating and induction

electronic hygrometer • electronic power supply

electronic hygrometer An electrical device for dots or dashes, depending on its lever™s position
measuring relative humidity, whose sensitivity (right or left). 2. For telegraphy (radio or wire), a
and stability have been increased by the addition keyboard that produces perfectly timed Morse
of active amplifying devices. code output that corresponds to the operator™s
electronician See ELECTRONICS TECHNICIAN. typed input. 3. An electronic device for opening
electronic induction See ELECTROSTATIC IN- an electronic lock.
DUCTION. electronic keyer See ELECTRONIC KEY, 1.
Electronic Industries Association Abbreviation, electronic lock A lock that will open only after ap-
EIA. An American association of electronic manu- plication of a special coded sequence of signals.
facturers and engineers. It sets standards, dis- electronic mail Also called e-mail. A communica-
seminates information, provides industry- tions system that allows people to leave digital
government liaison, and maintains public rela- text messages for each other. It is popular among
tions for the industry. users of personal computers. Operates through
electronic information processing The use of the telephone lines using terminal emulation
electronic equipment (especially digital comput- software and a modem. It can also be used via
ers and attendant devices) to perform mathemat- amateur radio packet communications.
ical operations on data entered into the system in electronic microammeter See FET CURRENT
the form of electrical signals. Also see DATA PRO- METER and TRANSISTOR CURRENT METER.
CESSING. electronic microvoltmeter See MICROVOLT-
electronic instrument An instrument whose cir- METER.
cuit uses active devices for increased sensitivity electronic milliammeter See FET CURRENT ME-
over that of the electrical counterpart, and for TER and TRANSISTOR CURRENT METER.
minimum loading of a device under test. Com- electronic millivoltmeter A millivoltmeter that
pare ELECTRICAL INSTRUMENT. uses an amplifier ahead of an analog or digital in-
electronic integrator A active device (such as an dicator to provide high input impedance and in-
operational amplifier) for performing mathemati- creased sensitivity.
cal integration. Also see INTEGRATOR, 2. electronic multimeter A voltohm-milliammeter
electronic intelligence 1. Information exchanged that uses active amplifying devices. Also see
by electronic means. Examples: radio messages, ELECTRONIC INSTRUMENT.
radar information, and computer data. 2. The electronic multiplier A device, such as a Hall gen-
faculties of reasoning and decision making, as erator, whose output is equal (or proportional) to
apparently simulated by a high-level computer. the product of two inputs (i.e., it can perform
electronic interference The malfunctioning of a arithmetic multiplication).
device because of nearby currents, voltages, or electronic music 1. Music produced by a combi-
electromagnetic fields. nation of electronic oscillator, amplifier, and
electronic inverter An electronic device for con- loudspeaker. A number of successful instru-
verting direct current (dc) to alternating current ments have been developed. See, for example,
(ac). Typically, an inverter is a transistorized ELECTRONIC CARILLON, ELECTRONIC ORGAN,
square-wave oscillator inductively coupled to ac ELECTRONIC PIANO, and THEREMIN. 2. The
output terminals. The dc to be inverted energizes electronically amplified sounds of conventional
the transistors, which perform the switching musical instruments.
function at the rate determined by the compo- electronic organ A musical instrument with a key-
nents of the circuit. Also see INVERTER, 1. board similar to that of a conventional organ, in
which tones produced by oscillators or electri-
cally driven reeds are processed and amplified for
delivery to a system of loudspeakers.
electronic packaging See ENCAPSULATION.
+ ac electronic part A lowest replaceable unit, or com-
Oscillator Amplifier
dc Input Input ponent, in an electronic circuit.

electronic phase meter An electronic instrument
for measuring phase difference. Direct readings,
in degrees of lead or lag, are visible on an analog
scale or as a digital readout.
electronic inverter
electronic photoflash A transistorized light-inten-
sity meter. Also see ELECTRONIC INSTRUMENT.
electronic jamming The deliberate transmission electronic piano A musical instrument having the
of electromagnetic energy for the purpose of in- keyboard of a conventional piano and provided
terfering with the operation of a device or devices. with electronic amplification.
electronic key 1. For telegraphy (radio or wire), an electronic power supply A power supply using
electronic circuit that generates a continuous transistors or integrated circuits for stabilization
string of accurately spaced and timed Morse code and output control.
248 electronic precipitator • electronic watch

electronic precipitator See DUST PRECIPITATOR. electronic stimulator A device for applying con-
electronic product Any commercially manufac- trolled electrical pulses to the body to stimulate
tured electronic device, intended for purchase by muscles or nerves during diagnosis or therapy.
the public, by industry, or by government. electronic stroboscope A stroboscope that uses a
electronic profilometer An electronic instrument rate-calibrated oscillator, rather than a mechanical
for measuring surface roughness. contactor to generate pulses that strobe the lamp.
electronic ratchet A stair-step circuit or other ar- electronic subtracter An electronic circuit for per-
rangement functioning in the manner of an forming arithmetic subtraction.
equivalent electromechanical stepping switch. electronic surge A sudden, large increase in the
Also see COMMUTATOR. current in a conductor. Can be caused by an elec-
electronic reconnaissance In military applica- tromagnetic pulse; can also occur when utility
tions, the use of electronic systems to locate en- power is restored following a blackout.
emy installations (such as radio stations, electronic switch 1. A nonmechanical device,
guided-missile sites, and radar bases). such as a flip-flop or gate, whose characteristic
electronic rectifier A rectifier that uses active de- on-off operation can be used to make and break
vices to change alternating current (ac) to direct an electric circuit. Compare CONTACT SWITCH.
current (dc). 2. A device using electronic gating and sequenc-
electronic regulator A voltage regulator that uses ing circuits to present several signals alternately
active electronic circuits, as opposed to a reactor- to the single input of an oscilloscope, allowing si-
type or electromechanical device. See, for exam- multaneous viewing of the signals.
ple, VOLTAGE REGULATOR. electronic tachometer An instrument for measur-
electronic relay 1. A switching circuit that uses ing angular velocity, usually in revolutions per
one or more transistors, and performs the relay minute (rpm). Ideally, the response is indepen-
function without moving parts. 2. An electronic dent of sensor voltage amplitude, showing only
component designed to switch when gating sig- the number of pulses per unit time reaching the
nals are applied (e.g., triac, diac, or silicon- meter circuit.
controlled rectifier). electronic thermal conductivity The thermal-
electronic resistor 1. The effective internal collec- conductivity component, resulting from the
tor-emitter resistance of a common-emitter bipo- transfer of heat by electrons and holes.
lar-transistor stage. 2. The effective internal electronic thermometer An instrument for mea-
drain-source resistance of a field-effect transistor suring temperature as a result of variations in a
(FET) stage. temperature-sensitive component, such as a re-
electronics The branch of physics concerned with sistor, thermocouple, or thermistor.
the behavior and application of electric charge electronic timer An electronic circuit or device for
carriers in components, devices and systems that automatically timing a process or observed event.
accomplish amplification, oscillation, signal pro- Most are based on the time constant of a stable
cessing, and/or switching. resistance-capacitance (RC) circuit. Compare
electronics engineer A trained professional ELECTROMECHANICAL TIMER.
skilled in the physics and mathematics of elec- electronic tube See ELECTRON TUBE.
tronics, and in the theory and application of basic electronic tuning Variation of the resonant fre-
engineering and related subjects. Compare quency of a device or circuit by changing the bias
ELECTRICAL ENGINEER. voltage or current of a controlling electronic com-
electronics service person An electronics techni- ponent.
cian skilled in repairing and maintaining elec- electronic voltmeter A voltmeter that uses elec-
tronic equipment. Also called electronics service tronic amplification ahead of the indicating meter
technician. to provide high input impedance and increased
electronic shutter See KERR CELL. sensitivity. Also see FET VOLTMETER and TRAN-
electronics technician A professional skilled in SISTOR VOLTMETER.
building, testing, repairing, or maintaining elec- electronic voltohmmeter A voltohmmeter that
tronic equipment. uses electronic amplification ahead of the indi-
electronics technology The theory and practical cating meter to provide high input impedance
application of electronics. Taught as a subengi- and increased sensitivity.
neering major, usually in two-year junior colleges electronic typewriter A typewriter with a micro-
or technical institutes, awarding the degree of as- computer that provides features, such as buffer-
sociate in arts (AA) or associate in science (AS). ing, automatic repeat, erase memory, and
electronic stethoscope A stethoscope employing paragraph/page memory.
a miniature microphone, amplifier, and ear- electronic warfare The use of electronic systems
phones. The amplifier gain is continuously con- for military purposes, including interfering with
trollable, and its bandwidth often selectable for an enemy™s use of similar systems.
emphasizing particular heart sounds and other electronic watch 1. A watch whose movement is
body noises. a tiny, high-frequency, alternating-current (ac)
electronic watch • electron stream

motor driven by a stable oscillator. 2. Any minia- repulsion. 2. The movement of an electron as a
ture timepiece incorporating solid-state circuitry, charged mass. In an electric field, this movement
but especially one using a digital readout. simulates that of a free-falling body in a gravita-
electronic wattmeter A wattmeter in which an tional field.
amplifier is used for increased sensitivity. electron multiplication 1. In a gas discharge, the
electronic waveform synthesizer A signal gener- production of additional electrons as a result
ator that delivers an alternating or pulsating sig- of collisions between electrons, atoms, and
nal whose waveform can be tailored by means of molecules. 2. The increased production of elec-
adjustable circuit components. trons in a semiconductor when avalanche occurs.
electron lens A device that focuses an electron electron-multiplier tube 1. A vacuum tube utiliz-
beam in a manner similar to the focusing of light ing a sequence of secondary emissions for in-
rays by a glass lens. Also see ELECTROSTATIC creased current amplification. Electrons from the
LENS, ELECTROMAGNETIC LENS, and WAVE- cathode strike a positively biased dynode with a
GUIDE LENS. force that dislodges secondary electrons, which,
electron magnetic moment The energy per unit upon joining those first emitted, are reflected to a
flux density available in an electron. Approxi- second positive dynode that contributes more
mately equal to 9.2848 — 10“24 joule per tesla. secondary electrons, reflecting the total to a third
electron mass See MASS OF ELECTRON AT REST. positive dynode, etc. The last dynode in the chain
electron microscope A microscope in which the reflects the enhanced beam to an anode collector
source of illumination is an electron beam fo- that passes the high current to an external cir-
cused by electromagnetic lenses. It allows much cuit. 2. See PHOTOMULTIPLIER TUBE.
greater magnification than is possible with opti- electronography Printing by means of the electro-
cal microscopes. static transfer of ink from a printing plate across
a gap to an impression cylinder.
electron optics See ELECTRO-OPTICS.
electron orbits See ELECTRON SHELLS.
Electron gun
electron oscillator A device in which oscillation is
obtained by causing electrons to move in an os-
+dc cillatory path, to travel in bunches, etc. Exam-
ples: klystron, magnetron, and traveling-wave
electron pair Two electrons from adjacent atoms,
which sometimes share the same orbits, but al-
ways produce a bond between two adjacent
Magnetic lens
electron-pair bond The bond between an electron
electron physics The physics of electronics, usu-
ally from a highly theoretical viewpoint.
electron-proton magnetic moment ratio A phys-
Magnetic lens
ical constant whose value is approximately equal
to 658.211, derived from the division of the mag-
netic moment of the electron by that of the pro-
electron recoil The recoil of an electron from a
photon it has collided with.
Magnetic lens
electron rest mass See MASS OF ELECTRON AT
electron scanning Deflection of an electron beam.
electron shells The spheres, concentric with the
nucleus of an atom, that represent the median
electron microscope distances from the nucleus around which elec-
trons migrate.
electron spin The rotation of an electron (i.e.,
electron mirror A reflector of electrons”especially
around its axis). This motion is independent of
a dynode element in a photomultiplier tube or
the electron™s movement around the nucleus of
electron-multiplier tube.
an atom.
electron motion 1. The movement of electrons in
electron stream 1. The beam of electrons gener-
a conductor, semiconductor, or space, as the
ated by the electron gun in a cathode-ray tube.
result of electric or magnetic attraction or
250 electron stream • electrophorus

2. The electrons moving between the cathode and plug. The force exerted by the field on ions in the
plate in an electron tube. liquid causes it to flow.
electron-stream instrument See ELECTRON- electropad The skin-contacting electrode of an
BEAM INSTRUMENT. electrocardiograph.
electron-stream meter An oscilloscope (or cath- electropathy See ELECTROTHERAPY.
ode-ray tube alone) used as a device for making electrophilic Pertaining to the tendency to seek
measurements. electrons.
electron-stream transmission efficiency The ra- electrophobia An irrational fear of electricity, a
tio of the current through a positive electrode to psychological condition sometimes exhibited by
the current impinging on it. In a tube, for exam- victims of serious electric shock.
ple, some electrons are absorbed by the plate, electrophonic effect Sound heard by a person
and others are reflected. when an alternating current is passed through
electron telescope A telescope using a combina- some part of the body.
tion of a glass lens, photocathode, and electro- electrophoresis The movement of dielectric parti-
static focusing. Light from the object is focused cles through a liquid in which they are sus-
on the photocathode by the lens, the electrons pended, produced by the electric field between
emitted being focused electrostatically on a phos- electrodes immersed in the suspension.
phorescent viewing screen. electrophoresis equipment 1. Any device in-
electron transit time The time required for an elec- tended for the purpose of depositing a dielectric
tron to travel a given distance. For a vacuum tube, material onto a metal by means of electrophore-
the upper frequency limit of operation is governed sis. 2. Any equipment in which electrophoresis
by the time required for an electron to reach the occurs.
plate after leaving the cathode. Transit time is electrophoresis scanner A device that senses the
usually stated in fractions of a microsecond. movement of charged particles caused by elec-
electron tube An evacuated or gas-filled chamber trophoresis effects.
in which electrons are emitted (usually by a hot electrophoretic deposition A type of deposition in
cathode) and controlled (usually by a voltage ap- which a low-voltage direct current passing
plied to a grid electrode). through a colloidal suspension of dielectric poly-
electron unit See ELEMENTARY CHARGE. mer particles deposits them as a coating on a
electron velocity The velocity acquired by an elec- metallic body (the anode in the process). It can
tron that moves between two points having a provide a better coating than one obtained with
given potential difference. Also see ELECTRON spray painting or dipping.
electronvolt Abbreviation, eV. The energy ac-
quired by a unit charge moving through a poten- Cathode
+ ’
Anode part
tial difference of one volt; it is equal to to be coated
approximately 1.6022 — 10“19 joule.
electron-wave tube A tube, such as a klystron or
traveling-wave tube, in which electrons traveling
at different velocities interact with each other,
modulating the electron stream.
electro-oculogram A recording of the voltage that
is found between the anterior and posterior parts
of the eyeball.
Suspended particles
electro-optical transistor A phototransistor or
pair of phototransistors in a single package. Used
electrophoretic deposition
in electronic circuits to sense changes in light
electro-optical valve See KERR CELL.
electro-optic radar A form of radar that makes electrophorus A simple device used to demon-
use of visual apparatus for locating a target. strate electrostatic generation and induction. It
electro-optics The branch of electronics dealing consists of a smooth metal plate at the end of an
with related electrical and optical phenomena: insulating handle and an accompanying cake of
photoelectricity, light generation, laser technol- resin or hard rubber. The cake is rubbed with
ogy, light amplification, etc. It is also concerned cat™s fur, making it negatively charged. The metal
with electronic phenomena that are analogous to plate is touched to the charged cake; by induc-
optical phenomena, such as electronic focusing, tion, it acquires a bound positive charge on the
reflection, refraction, diffraction, etc. Also called face that touched the cake and a free negative
electron optics and optoelectronics. charge on the opposite face. When the plate is
electro-osmosis Causing liquids to flow by apply- lifted and its top face touched momentarily with
ing an electric field across the walls of a porous the finger or grounded, the negative charge leaks
electrophorus • electrostatic field

off, often with a sharp spark, but the positive for certain mental disorders. 2. The electric shock
charge remains. used in the therapy described in 1.
electrophotographic process See XEROGRAPHY. electrospinograph An instrument that senses and
electrophotography The production of photographs records electrical impulses from the spinal cord.
by means of electricity. See XEROGRAPHY. electrostatic Pertaining to stationary electric
electrophotometer A light-intensity meter using a charges and fields, and their application.
photoelectric sensor and a meter, but usually not electrostatic actuator A device for measuring the
incorporating an amplifier. Compare ELEC- sensitivity of a microphone. Electrostatic charges
TRONIC PHOTOMETER. produce forces on the diaphragm of the micro-
electrophrenic respiration A system of inducing phone, and the resulting output is recorded.
respiration in which one or both of the phrenic electrostatic amplifier See DIELECTRIC AMPLI-
nerves (i.e., of the diaphragm) are stimulated FIER.
electrically to produce contractions of the di- electrostatic charge See ELECTRIC CHARGE.
aphragm muscles. electrostatic component The electric component
electrophysiology 1. The study of electrical pro- of an electromagnetic wave. It is perpendicular to
cesses in the human body. 2. The study of how the magnetic component and can be thought of
electrical impulses affect, and are produced by, as the wave™s voltage component.
body organs. electrostatic constant See ELECTRIC CON-
electroplaques In electric fish, small voltage- STANT.
generating cells that are connected in series- electrostatic convergence See ELECTROSTATIC
parallel networks. FOCUSING.
electroplate 1. To cause one metallic substance to electrostatic cooling Accelerated cooling of a body
adhere to the surface of another through the ef- through the application of an intense electro-
fects of electrolysis. 2. A metal plating deposited static field. The body must be in a free convection
via electrolysis. state, a corona discharge must be present, and
electroplating Depositing one metal on the sur- the field must not be uniform.
face of another by electrolytic action. electrostatic copier A document-copying appara-
electropolar Having electrical polarity (either posi- tus that uses electrostatic effects to reproduce
tive or negative). printed material.
electropolishing An electrolytic method of electrostatic coupling See CAPACITANCE COU-
smoothing a rough metal surface. The workpiece PLING.
to be polished becomes the anode of an elec- electrostatic deflection In a cathode-ray tube,
trolytic cell in which electrolytic action dissolves deflection of the electron beam by the electro-
tiny surface irregularities. static fields between pairs of internal horizontal
electropositive Having positive electrification or and vertical deflecting plates. It is primarily used
polarity. Compare ELECTRONEGATIVE. in laboratory oscilloscopes. Compare ELECTRO-
electropsychrometer An electronic instrument for
+150 V
humidity measurements.
electroreduction In electrolysis, reduction of the
cathode electrode.
electrorefining The refining of metals by means of
Lines of
electroretinograph An instrument used to mea-
sure the electrical response of the human retina
to light.
electroretinography The process of detecting and ’150 V
measuring electrical impulses from the retina.
electroscope An instrument for detecting electric electrostatic deflection
charges and fields. The common type uses a pair
of gold-leaf strips hung from the end of a metal
rod in a glass tube or jar. When the exposed end electrostatic electrometer See KELVIN ABSO-
of the rod is brought near a charged object, the LUTE ELECTROMETER.
leaves repel each other and spread apart. electrostatic electrophotography See XEROG-
electrosection The use of an arc-generating device RAPHY.
for making surgical incisions. electrostatic energy The potential energy con-
electrosensitive recording See ELECTRIC RE- tained in an electrostatic field (e.g., the energy in
CORDING. a charged capacitor). Compare ELECTROKI-
electroshock 1. The system of creating a con- NETIC ENERGY.
trolled electric shock in the brain as a treatment electrostatic field A stationary electric field.
252 electrostatic field intensity • electrostatic stress

electrostatic field intensity An expression of the in which visual images are converted to electro-
strength of an electrostatic field. Usually ex- static images.
pressed in volts per meter, millivolts per meter, or electrostatic recording A method of recording
microvolts per meter. that employs a signal-controlled electric field.
electrostatic flux The flux existing around an electrostatic relay A high-input-impedance relay
electric charge or a charged body. consisting of two polarity-controlled contacts; op-
electrostatic focusing In a cathode-ray tube, elec- posite charges on the contacts close the relay,
tron-beam focusing achieved by varying the dc and like charges open it.
bias voltage on a focusing electrode. Compare electrostatics The branch of electricity concerned
ELECTROMAGNETIC FOCUSING. with electrical charges at rest. Compare ELEC-
electrostatic galvanometer A galvanometer oper- TRODYNAMICS and ELECTROKINETICS.
ating on the principle of the electrostatic volt- electrostatic screen A shield against electric flux
meter. consisting of a number of straight, narrowly sep-
electrostatic generator A device for producing arated rods or wires joined at only one end. The
high-voltage electric charges; e.g., a Van de shield has little effect on magnetic flux. Also
Graaff generator. called Faraday shield.
electrostatic headphone A device similar to an electrostatic separator A device for separating
electrostatic speaker, but held against the head fine particles from a mixture by exposing the mix-
for private listening. Incoming audio signals ture to an intense electrostatic field.
cause attraction and repulsion among charged electrostatic series A list of materials arranged in
plates, resulting in acoustic vibration. this sequence: any one of them becomes posi-
electrostatic hysteresis The tendency of some di- tively electrified when rubbed with another lower
electrics (especially ferroelectric materials) to sat- in the list, or negatively electrified when rubbed
urate and retain a portion of their polarization with another higher in the list. Compare ELEC-
when an alternating electric field to which they TROMOTIVE SERIES.
are exposed reverses polarity. This causes the electrostatic shield Any metallic enclosure de-
charge to lag behind the charging force. signed to confine an electric field.
electrostatic induction The charge acquired by a electrostatic speaker A loudspeaker whose vi-
body inserted into an electric field. Compare brating diaphragm is one of two plates in a large
ELECTROMAGNETIC INDUCTION. air-dielectric capacitor, the other being a closely
electrostatic instrument See ELECTROSTATIC situated metal plate (or plug). An audio voltage
VOLTMETER. applied to the plates causes them to vibrate. Also
electrostatic lens An assembly of deflecting plates called capacitive loudspeaker and capacitor loud-
or cylinders, whose electric field causes an elec- speaker.
tron beam to converge or diverge in much the
same way as a visible light beam passing through
an optical lens. Compare ELECTROMAGNETIC
electrostatic loudspeaker See ELECTROSTATIC
electrostatic memory A memory unit in which an
information bit is stored as an electric charge.
electrostatic memory tube A cathode-ray tube in
which information bits are stored in capacitive
cells swept by the scanning electron beam.
electrostatic microphone See CAPACITOR MI-
electrostatic phase shifter See PHASE-SHIFTING
electrostatic potential In an electric field, the po-
tential energy represented by the voltage between
the two elements creating the field, or between
any two points within the field. electrostatic sprayer An equipment for spray
electrostatic precipitator See DUST PRECIPITA- painting in which fine droplets of paint are at-
TOR. tracted by an electrostatic field to the surface to
electrostatic printer A computer output periph- be coated.
eral in which the printing medium, a fine dust, is electrostatic storage See ELECTROSTATIC MEM-
fused by heat onto paper that has been charged ORY.
according to the data being represented. electrostatic stress 1. Stress in the vicinity of a
electrostatic process 1. Any process that uses charged body or particle. 2. See DIELECTRIC
electrostatic action. 2. A method of photography STRESS.
electrostatic transducer • element

electrostatic transducer See CAPACITANCE electrosynthesis Chemical synthesis produced by
TRANSDUCER. means of electric currents or fields.
electrostatic tube of flux The space between elec- electrotape Also called electronic tape measure.
tric lines of flux going through adjacent points on Any device that measures distance by electronic
the boundary of a given area in an electric field. means, such as radar or sonar.
electrostatic tweeter A small electrostatic electrotechnology See ELECTRICAL TECHNOL-
speaker for reproducing high-frequency sounds. OGY and ELECTRONICS TECHNOLOGY.
Compare WOOFER. electrotellurograph An instrument for measuring
electrostatic unit Abbreviation, esu. A unit of ground currents.
measure in the electrostatic system of cgs units. electrotherapeutics See ELECTROTHERAPY.
Also see CENTIMETER-GRAM-SECOND. Com- electrotherapy The treatment of disorders or dis-
pare ELECTROMAGNETIC UNIT. eases by electrically induced heat”especially by
electrostatic vector See ELECTRIC VECTOR. DIATHERMY.
electrostatic voltmeter An indicating meter electrothermal 1. Pertaining to electrically gener-
whose movement consists of a stationary metal ated heat. 2. Pertaining to a combination of elec-
plate near a rotating metal plate. A voltage ap- tricity and heat.
plied to the plates charges them, and the attrac- electrothermal device A device whose operation
tion between them causes the movable member depends on the heat generated by an electric cur-
to rotate against the torque of a returning spring rent (e.g., a bolometer, hot-wire ammeter, ther-
over an arc proportional to the voltage. mocouple, or varistor).
electrothermal expansion element A thermo-
static element, such as a bimetallic strip, whose
expansion is used in heat-sensitive switches.
scale electrothermal instrument A hot-wire or thermo-
couple-type meter.
electrothermal recorder See ELECTRIC RE-
electrothermic See ELECTROTHERMAL.
electrothermics The study and application of the
heating effects of electricity in conductors and
electrotitration In chemistry, the completion of
Movable Input
titration, as indicated by an electrical measure-
ment, such as of the resistance of the solution be-
ing titrated.
electrotonic Pertaining to ELECTROTONUS.
electrotonus Modification of a nerve™s sensitivity
by passing a constant current through it.
electro-ultrafiltration In physical chemistry, fil-
electrostatic voltmeter
tering a colloidal suspension by electro-osmosis.
electrovalence 1. The number of charges acquired
electrostatography See XEROGRAPHY. by an atom gaining electrons. 2. The number of
electrosteel See ELECTRIC STEEL. charges forfeited by an atom losing electrons. 3.
electrostenolysis The deposition of certain metals Valence resulting from electron transfer between
from a solution in capillary tubes when an elec- atoms and the resulting creation of ions.
tric current passes through the solution. electrovalency See ELECTROVALENCE.
electrostimulation Electrical excitation of nerves electrovalent bond See IONIC BOND.
for the relief of pain. electrowin To recover (win) a metal from a solution
electrostriction In certain materials, the physical of its salts by means of electrolysis.
contraction that occurs when a voltage is applied. electrum A natural alloy of gold and silver.
Compare MAGNETOSTRICTION. element 1. See ELECTRODE. 2. A circuit compo-
electrostrictive ceramic A ceramic exhibiting nent intended for a specific purpose. 3. A spe-
ELECTROSTRICTION when voltage is applied. cific part of an antenna array (e.g., driven
electrostrictive relay A relay in which the mov- element or parasitic element). 4. A fundamental,
able contact is carried by a bar of electrostrictive unique substance whose atoms are of only one
material, such as barium titanate. A control volt- kind (examples: aluminum, carbon, silicon, and
age deforms the material, causing the contacts to sulfur). There are more than 100 elements, some
close. man-made. Elements combine to form com-
electrosurgery Surgery, sometimes bloodless, pounds. 5. A circuit, such as an AND gate, that
achieved with diathermy-like equipment. See can be taken as a unit because it performs
DIATHERMY, 2. a special function. 6. In digital computer
254 element • ELSIE

operations, a subunit of a category that cannot
be further categorized [e.g., a bit (word element)
or a record (file element)]. a


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