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numbers of ions in a gas, liquid, or solid (e.g., ion- the presence of smoke or other particles as a re-
ization of the upper atmosphere). sult of changes in the IONIZATION CURRENT
ionization arc The electrical discharge resulting through the air. When the ionization current sud-
from the ionization of a material because of high denly changes, a signal is sent to an alarm cir-
voltage. cuit.
ionization chamber An enclosure containing a gas ionization time The interval, usually measured in
and a pair of electrodes between which a high microseconds or milliseconds, between the in-
voltage is applied. Radiation, such as X rays or stant that an ionizing potential is applied to a
radioactive particles, passing through the walls of gas, and the instant at which the gas begins to
the chamber ionize the gas, creating an ionization ionize. Compare DEIONIZATION TIME.
381
ionization trail • IRF


ionization trail The ionized path of a meteor as it ionospheric forecasting Predicting ionospheric
passes through the upper atmosphere. conditions. Radio propagation data is derived
ionize To cause the electrons in a substance, from such predictions.
particularly a gas, to move freely from atom to ionospheric layers The respective layers of the
atom. ionosphere: D layer (at an altitude of about 30 mi
ionized gas A gas whose atoms, under the influ- or 50 km), E layer (at an altitude of about 50 mi
ence of a strong electric field or IONIZING RADIA- or 80 km), the F1 layer (at an altitude of about
TION, have become positive or negative ions. 125 mi or 200 km), and the F2 layer (at an alti-
ionized layer See KENNELLY-HEAVISIDE LAYER. tude of about 180 mi or 300 km). The F1 layer is
ionized liquid See ELECTROLYTE. generally present only in the daytime.
ionizing radiation 1. Any high-energy electromag- ionospheric propagation Propagation of radio
netic radiation that causes ionization in a gas waves by means of reflection or refraction by the
through which the field passes. Examples: ultra- ionosphere. Also see HOP; INCIDENT WAVE;
violet, X rays, and gamma rays. 2. High-speed IONOSPHERE; MULTIHOP PROPAGATION; RE-
atomic nuclei (e.g., protons or alpha particles). FLECTED WAVE, 1; REFRACTED WAVE; and
ion migration The movement of ions through a SKYWAVE.
solid, liquid, or gas because of the influence of an ionospheric storm Turbulence in the ionosphere,
electric field. usually accompanied by a magnetic storm and
ionosphere 1. Any of several ionized regions at caused by high-speed particles emitted from an
specific altitudes above the earth™s surface. eruption on the sun.
These layers cause absorption and refraction of ion sensor A device whose operation is based on
electromagnetic (EM) fields at some radio fre- the detection of ions and the delivery of a propor-
quencies. The D layer exists at an altitude of tionate voltage. Examples are the Geiger counter,
about 30 miles (50 km) and is ordinarily present halogen gas leak detector, mass spectrometer,
only on the daylight side of the planet. This layer and vacuum gauge.
does not contribute to, and in fact sometimes ion spot See ION BURN.
hinders, wireless communications. The E layer, ion trap See BENT-GUN CRT.
about 50 miles (80 km) above the surface, also ion-trap magnet An external (usually double)
exists mainly during the day, but nighttime ion- magnet used with a television picture tube to de-
ization is sometimes observed. The E layer can flect the ion beam away from the screen. This pre-
facilitate medium-range radio communication at vents ION BURN.
certain frequencies. The uppermost regions are I/O port That part of a computer providing, via a
the F1 and F2 layers. The F1 layer, normally pre- connector, a point through which data can enter
sent only on the daylight side of the earth, forms from, or exit to, peripheral equipment.
at about 125 miles (200 km) altitude; the F2 layer IP 1. Abbreviation of PLATE CURRENT. 2. Abbrevi-
exists at about 180 miles (300 km) more or less ation of PEAK CURRENT.
around the clock. Sometimes the distinction be- I-phase carrier In color television, a carrier sepa-
tween the F1 and F2 layers is ignored, and they rated by 57 degrees from the color subcarrier.
are spoken of together as the F layer. I-picture A video image that is coded using only
ionospheric disturbance See IONOSPHERIC data that it contains.
STORM. ipm Abbreviation of INCHES PER MINUTE.
ips Abbreviation of INCHES PER SECOND.
IR 1. The product of current and resistance (see,
for example, IR DROP). 2. Abbreviation of INSU-
LATION RESISTANCE. 3. Abbreviation of IN-
FRARED.
Ir Symbol for IRIDIUM.
Ir Symbol for CURRENT in a resistor.
IRAC Abbreviation for Interdepartment Radio Advi-
sory Committee (a federal government group in
the United States).
IR diode See INFRARED DIODE.
IR drop The voltage drop (E) across a resistance (R)
when there is a current (I) through the resistor;
according to Ohm™s law, E = IR.
IRE Abbreviation for Institute of Radio Engineers,
the predecessor of the IEEE (Institute of Electrical
and Electronics Engineers).
IRED Abbreviation for INFRARED-EMITTING
DIODE.
IRF Symbol for RADIO-FREQUENCY CURRENT.
382 iridescence • Is


iridescence A sparkling, colorful appearance in a
material, resulting from refraction, internal re-
Needle
flection, and interference in light waves passing
through the substance. It is especially noticeable
in quartz and certain gems. Bearing
Enclosure
with
iridium Symbol, Ir. A metallic element of the plat-
with coil
spring
inum group. Atomic number, 77. Atomic weight,
Fixed
192.22.
Movable vane vane
iron Symbol, Fe. A ferromagnetic, metallic ele-
ment. Atomic number, 26. Atomic weight,
55.847. Iron (and its special form, steel) is widely
used in magnetic circuits.
iron/constantan thermocouple A thermocouple
consisting of a junction between wires or strips of Input
IRON and CONSTANTAN.
iron core A transformer or choke core made from
iron or steel. The core is usually laminated to re- iron-vane meter
duce eddy-current loss.
iron-core coil An inductor having an iron or steel
core, usually laminated to reduce eddy-current mal expansion is nonterminating and nonrepeat-
loss. ing.
iron-core IF transformer An intermediate-fre- irregularity 1. The condition of being nonuniform,
quency transformer having a core of powdered or rapidly fluctuating, rather than constant. 2. A
iron, a form of iron that has the advantage of high departure from normal operating conditions. 3.
permeability while greatly minimizing eddy cur- Nonuniformity in a surface. 4. Nonuniform distri-
rents. bution of matter. 5. Nonuniform distribution of
iron-core transformer A transformer whose coils data.
are wound on a core of laminated iron or steel. irregular wave A wave disturbance, or the plot of
iron loss Power lost in the iron cores of transform- such a disturbance versus time, that has a com-
ers, inductors, and electrical machinery as a re- plex, periodic, repeating nature.
sult of eddy currents and hysteresis. IR viewer A device that allows observation of im-
iron magnet A permanent magnet consisting of ages at infrared wavelengths. See SNIPERSCOPE
magnetized iron or a mixture of iron and nickel. and SNOOPERSCOPE.
iron oxide A compound of iron and oxygen, whose Is 1. Symbol for source current in a field-effect
most familiar form is common rust. The several transistor. 2. Symbol for screen current in a vac-
variants have characteristics that depend on the uum tube.
number of iron and oxygen atoms in the iron-
oxide molecule. See, for example, MAGNETITE
and RED OXIDE OF IRON.
iron pyrites Formula, FeS2. Natural iron sulfide
that occurs as bright yellow crystals in its natural
state.
iron-vane meter An alternating-current meter
whose movable element, a soft iron vane, carries
the pointer and pivots near a similar, stationary
vane. The vanes are mounted in a multiturn coil
of wire. The current flows through the coil, the re-
sulting magnetic field magnetizing the vanes.
Because the magnetic poles of the vanes are
identical, they repel each other; the movable vane
is deflected (against the torque of returning
springs) over an arc proportional to the current,
carrying the pointer over the scale.
irradiance The amount of radiant flux impinging
on a unit surface area; it is generally specified in
watts per square meter (W/m2).
irradiation 1. Exposure of a device to radioactivity
or X rays. 2. The total radiant power density that
is incident upon a receiving surface.
irrational number A number that cannot be ex-
pressed as the quotient of two integers. Its deci-
383
ISDN • isoplanar


ISDN Abbreviation for INTEGRATED SERVICES blocking direct current. Also called a BLOCKING
DIGITAL NETWORK. CAPACITOR.
ISCAN Abbreviation of inertialess steerable commu- isolating diode A diode used (because of its unidi-
nications antenna. rectional conduction) to pass signals in one direc-
I-scan A radar display in which the target is shown tion, but block them in the other direction.
as a complete circle, whose radius is proportional isolating resistor A high-value resistor connected
to the distance to the target. in series with the input circuit of a voltmeter or
I-signal With the Z-signal, one of the two signals oscilloscope to protect the instrument from stray
that modulates the chrominance subcarrier in pickup. In most voltmeters, this resistor is built
color television. The I-signal results from mixing into the probe.
a B-Y signal (with -0.27 polarity) and an R-Y sig- isolating transformer A power transformer, usu-
nal (with +0.74 polarity). ally having a 1:1 turns ratio, for isolating equip-
Isinglass Thinly laminated mica. ment from direct connection to the power line.
ISO Abbreviation for International Standards Orga-
nization.
ISO 9660 A standard format for producing CD- 117 Vac
ROM (COMPACT DISK READ-ONLY MEMORY)
mass storage media for use with computers. It is Neut
Hot
a part of the YELLOW BOOK scheme.
isobar 1. An atom whose nucleus has the same
weight as that of another atom but differs in To
atomic number. 2. On a weather map, a line con- equipment
necting points of equal pressure. Also see BAR, 1. Gnd
isochromal phenomena 1. Effects occurring at reg-
ular time intervals. 2. Effects of equal duration.
isochromatic Also orthochromatic. 1. The quality
of having or producing natural visible-light hues.
2. Color sensitivity excluding a response to red.
isochronal See ISOCHRONE.
isochrone On a map, a line connecting points of isolating transformer
constant time difference in radio-signal recep-
tion. It is useful in radiolocation and radionaviga-
tion. isolation The arrangement or operation of a circuit
isochronous Having identical resonant frequen- so that signals in one portion are not transferred
cies or wavelengths. to (nor affect) another portion.
isoclinic line See ACLINIC LINE. isolation amplifier See ISOLATING AMPLIFIER.
isodose Pertaining to points receiving identical isolation capacitor See ISOLATING CAPACITOR.
dosage of radiation. isolation diode 1. In an integrated circuit, a re-
isodynamic line On a map of the geomagnetic field verse-biased diode that is formed in the substrate
(the earth™s magnetic field), a line connecting to prevent cross-coupling and grounds. 2. See
points of equal flux density. ISOLATING DIODE.
isoelectric Having a potential difference of zero. isolation resistor See ISOLATING RESISTOR.
isoelectronic Having the same number of electrons. isolation transformer See ISOLATING TRANS-
isogonal 1. See ISOGONIC LINE. 2. Having uni- FORMER.
form magnetic declination at all points. isolator See OPTOELECTRONIC COUPLER.
isogonic line On a map of the geomagnetic field isolith A form of monolithic integrated circuit, in
(the earth™s magnetic field), a line connecting which the semiconductor is removed in certain
points of equal magnetic declination. places for the purpose of isolating different parts
isolantite An insulating ceramic. Dielectric con- of the circuit.
stant, 6.1. isomagnetic Having equal magnetic intensity.
isolated 1. Electrically insulated. 2. Separated in isomer A material that has the same atomic num-
such a way that interaction does not take place. ber or chemical formula as some other substance,
isolated input 1. An ungrounded input. 2. An in- but, because of a difference in the atomic struc-
put circuit with a blocking capacitor to prevent ture, is an entirely different substance. An exam-
the passage of direct current. ple is carbon; it can be either graphite (by far the
isolated location In a computer, a storage location more common form) or diamond.
that is hardware-protected from being addressed isophote On a graph of visible-light intensity, a
by a user™s program. curve joining points of equal brightness.
isolating amplifier See BUFFER, 1. isoplanar An integrated-circuit configuration in
isolating capacitor A series capacitor inserted in a which insulating barriers or metal oxides are fab-
circuit to pass an alternating-current signal while ricated among the bipolar elements.
384 isothermal process • -ize


isothermal process A physical or chemical pro- puters are commonly programmed to do this
cess in which there is no temperature change as thousands, millions, or billions of times. Such a
other factors vary. Compare ENDOTHERMIC RE- program must include a statement of acceptable
ACTION and EXOTHERMIC REACTION. accuracy so that it knows when to leave the iter-
isotope An atom having the same number of pro- ation loop.
tons as another atom, thereby composing the iterative impedance In a network consisting of
same chemical element, but having a different identical, cascaded sections, the input imped-
number of neutrons. Thus, deuterium is an iso- ance of a section to which the output impedance
tope of hydrogen. Some isotopes are radioactive of the preceding section is made equal.
[e.g., carbon 14 (an isotope of the more-common iterative routine A program or subroutine that
carbon 12)]. The two extra neutrons in carbon 14 provides a solution to a problem by iteration.
make it less stable than carbon 12. iterative transfer constant Symbol, P. A property
isotropic antenna A theoretically ideal antenna of ITERATIVE IMPEDANCE networks. If Ii is the
that transmits and/or receives electromagnetic network input current and Io is the network out-
fields equally well, and with 100-percent effi- put current, then P = loge(Io/Ii).
ciency, in all directions in three-dimensional free ITU Abbreviation for International Telecommunica-
space. tion Union.
isotropic radiator A theoretically ideal radiating ITV 1. Abbreviation of INDUSTRIAL TELEVISION.
element that transmits electromagnetic fields 2. Abbreviation for INTERACTIVE TELEVISION.
equally well, and with 100-percent efficiency, in I-type semiconductor See INTRINSIC SEMICON-
all directions in three-dimensional free space. DUCTOR.
Isup Symbol for suppressor current. IX Symbol for current in a reactance.
I(t) Symbol for INDICIAL RESPONSE. IY Symbol for current in an admittance.
ITD Abbreviation for INITIAL TIME DELAY. IZ Symbol for current in an impedance.
item 1. Component. 2. Any one of a number of -ize A suffix used, with some liberty, to form
similar or identical components, circuits, or sys- verbs from nouns. In electronics, this commonly
tems. refers to procedures or processes (e.g., to AN-
iteration Repeating a series of arithmetic opera- ODIZE, ELECTROCIZE, PLASTICIZE, or TRAN-
tions to arrive at a solution to a problem. Com- SISTORIZE).
J 1. Abbreviation for JOULE. 2. Symbol for JACK ing outer case or wrapper on a component, such
as a capacitor. 3. A shield can or shield box. 4. A
or CONNECTOR. 3. Symbol for EMISSIVE
heat-radiating or water-conducting enclosure
POWER.
used in cooling a power vacuum tube.
j (j operator) The square root of “1; an imaginary
jack panel A (usually metallic) panel in which a
number (usually denoted i in mathematics). As-
number of jacks are mounted, usually in some
signed to reactance values depicted on the verti-
order or sequence as denoted by labels.
cal axis of the resistance-reactance (RX) plane in
impedance vector diagrams, and whose currents
are 90 degrees out of phase with the current in
the resistive part of an alternating-current cir-
cuit.
jack A receptacle for a plug. A plug (a male connec-
tor) is inserted into a jack (a female connector) to
complete a circuit or removed from it to break a
jack panel
circuit.

jackscrew In a two-piece connector, a screw for
mating or separating the halves of the connector.
Jacob™s law A principle concerning the behavior of
motors. An electric motor develops maximum
power when Ei = 2Ebk, where Ei is the applied volt-
age and Ebk is the back voltage.
JAES Abbreviation for Journal of the Audio Engi-
neering Society.
jaff Colloquial term for radar jamming that com-
bines electronic and chaff techniques.
jag Distortion caused by temporary loss of syn-
chronization between the scanner and recorder in
jack a facsimile system.
jam input 1. A means of setting a logic line to the
desired condition by directly applying the desired
jack box A (usually metallic) box or can used to
high or low voltage. 2. A voltage applied to a logic
hold, shield, or protect a jack or group of jacks.
line to force it high or low.
jacket 1. The outer covering on a cable, as opposed
jammer 1. A radio transmitter or station used for
to the insulation or dielectric separating the indi-
the purpose of JAMMING communications be-
vidual conductors within the cable. 2. An insulat-


Copyright © 2001 by The McGraw-Hill Companies, Inc.
Click here for Terms of Use.
386 jammer • job stream


tween or among other stations. 2. A radio opera- JEDEC Acronym for Joint Electron Device Engineer-
tor who engages in the practice of deliberately ing Council.
JAMMING communications between or among jerk The rate of change of acceleration; the third
other stations. derivative of displacement.
jamming The deliberate use of countermeasures, JETEC Acronym for Joint Electron Tube Engineer-
such as malicious transmission of interfering sig- ing Council.
nals, to obstruct communications. jewel bearing A low-friction bearing used in elec-
jamming effectiveness The extent to which JAM- tric meters and other sensitive devices. It takes
MING is able to disrupt a service. It can be ex- its name from a jewel pivot (such as a sapphire) in
pressed quantitatively as the ratio of jamming the groove of which rides the pointed end of a ro-
signal voltage to jammed signal voltage. It can tating shaft. Also called jeweled bearing or jewel.
also be determined according to the percentage of jezebel A passive sonobuoy used in military appli-
data that is effectively obliterated. cations. It detects enemy submarine noises, and
JAN Abbreviation of JOINT ARMY-NAVY. transmits them by radio to a monitoring station.
janet A system for point-to-point communication JFET Abbreviation of junction field-effect transistor.
via meteor-trail forward scatter. It is generally JHG Abbreviation of JOULE HEAT GRADIENT.
used at very high frequencies (VHF). jig A device constructed especially for the purpose
Jansky noise Wideband, high-frequency electro- of holding an equipment or circuit board during




Y
magnetic noise generated by objects in interstel- its repair.
lar and intergalactic space. jitter A (usually small and rapid) fluctuation in a




FL
J antenna An end-fed half-wave antenna having a phenomenon, such as a quantity or wave, be-
quarter-wave, parallel-wire matching section. The cause of noise, mechanical vibration, interfering
entire antenna, when oriented vertically, resem- signals, or similar internal or external distur-
bles the letter J. bances. It is used especially in reference to
AM
cathode-ray-tube (CRT) displays.
J/K Abbreviation for joule(s) per Kelvin, the SI unit
of entropy; also the unit for the Boltzmann con-
stant.
Radiator
J-K flip-flop A transistor-resistor flip-flop stage
TE

»/2
producing an output signal even when both in-
puts are in the logic 1 state (high). It is so called
because its input terminals are labeled J and K.
Matching
J/(kg•K) Abbreviation for joule(s) per kilogram
section
Kelvin, the SI unit of specific heat capacity.
»/4
job A unit of computer work, usually consisting of
Coaxial
several program runs.
line
job control language An operating system lan-
guage used to describe the control requirements
for jobs within the system.
J antenna job control program A program that uses control
language statements and implements them as in-
structions controlling a job in an operating sys-
Janus antenna array (from Janus, an ancient Ro-
tem.
man god.) A Doppler-navigation antenna array
job control, stacked See SEQUENTIAL-STACKED
radiating forward and backward beams.
JOB CONTROL.
jar 1. (From Leyden jar) An obsolete unit of capac-
job flow control To control the order of jobs being
itance equal to 1/900 microfarad. 2. The con-
processed by a computer to make the most effi-
tainer for the elements of a storage cell.
cient use of peripherals and central processor
JASA Abbreviation for Journal of the Acoustical So-
time”either manually or by an operating system.
ciety of America.
job library A series of related sets of data that will
J-carrier system In carrier-current (wired/wire-
be loaded for a given job.
less) telephony, a broadband system that pro-
job-oriented terminal A terminal that produces
vides 12 telephone channels at frequencies up to
data in computer-ready form.
140 kHz.
job statement A control statement identifying the
JCET Abbreviation of Joint Council on Educational
beginning of a series of job control statements for
Television.
a job.
JCL Abbreviation of job control language.
job step The execution of a computer program ac-
J-display A radar display having a circular time
cording to a job control statement; several job
base. The transmitted pulse and reflected (target)
steps can be specified by a job.
pulse are spaced around the circumference; dis-
job stream In a processing system, a group of con-
tances can be measured circumferentially be-
secutively run jobs.
tween them.




Team-Fly®
387
jogging • J rule


jogging Rapid, repetitive switching of power to a joule Abbreviation, J. The SI unit of work. One
motor to advance its shaft by small amounts. joule is the work performed when the point of ap-
Also called inching. plication of one newton is moved one meter in the
Johnson counter See RING COUNTER. direction of the applied force. Also see NEWTON.
Johnson curve A spectral curve (important in ap- Joule calorimeter A heat-measuring device that
praising solar cell performance) for air mass zero operates electrically.
(i.e., for conditions beyond the earth™s atmosphere). Joule constant See MECHANICAL EQUIVALENT
Johnson-Lark-Horowitz effect The resistivity OF HEAT.
gained by a metal or degenerate semiconductor Joule effect 1. The heat resulting from current
(one in which conduction is nearly equal to that flowing through a resistance. 2. See MAGNE-
of a simple metal) because of electron scattering TOSTRICTION.
by impurity atoms. joule heat See JOULE EFFECT, 1.
Johnson noise See THERMAL NOISE. joule heat gradient The rate of change in the tem-
Johnson-Q feed system See Q-ANTENNA. perature of a resistive object through which a
join Also called disjunction. The logical inclusive- current flows.
OR operation. joule meter An integrating wattmeter producing
joined actuator A form of multiple circuit breaker readings in joules.
in which the opening of one circuit results in the Joule™s law The rate at which heat is produced by
opening of all circuits. current flowing in a constant-resistance circuit is
joint See JUNCTION, 1. proportional to the square of the current.
joint circuit A communications circuit shared by journal A file of messages within an operating sys-
two or more services. tem, providing information for restarts and his-
joint communications Communication facilities torical analysis of system functioning.
being used by more than one service of the same joystick A two- or three-dimensional potentiome-
country. ter with a movable lever, allowing control of a pa-
joint denial The logical NOR (NOT-OR) operation. rameter, according to the position of the lever in
joint-force sensor A feedback servo device that pre- the up/down and left/right directions. It is often
vents a robot joint from exerting excessive force. It used in computer games for the purpose of ma-
works by detecting the mechanical resistance the nipulating images on a screen. In some such
robot arm encounters. If the resistance becomes devices, the lever can be rotated clockwise or
too great, the joint force is reduced or removed. counterclockwise to obtain additional functions.
jolt 1. Colloquialism for KILOVOLT. 2. Colloquial-
ism for ELECTRIC SHOCK. 3. Colloquialism for
TRANSIENT. 4. Colloquialism for a lightning dis-
charge.
Joly transformer A frequency-tripling transformer
whose frequency-multiplying action depends on
the nonlinearity of the magnetic induction curve
of the core material.
Jones plug A special form of polarized receptacle
having numerous contacts.




joystick

JPEG Abbreviation of Joint Photographic Experts
Group.
JPEG image compression An image-compression
scheme that eliminates redundancies, greatly re-
Jones plug ducing the necessary digital storage space. The
process is fast enough to allow animated graphics
j operator See J. at moderate speed.
Josephson effect The phenomenon, predicted by JPL Abbreviation of Jet Propulsion Laboratory.
Brian Josephson, wherein a current flows across J-pole antenna See J ANTENNA.
the gap between the tips of two superconductors J rule During transitions of orbital electrons from
brought close together; a high-frequency wave is higher to lower energy states (accompanied by
generated. the emission of photons), changes in the inner
Joshi effect The phenomenon whereby current in quantum number can only be by a factor of 0 or
a gas changes as the result of irradiation by light. +1, or “1.
388 J scan • juxtaposed images


J scan See J DISPLAY. semiconductor pn junction. 3. Loss occurring at
J scope A radar device that produces a J DISPLAY. an electrical connection because of poor bonding.
JSR Abbreviation of jump to subroutine. junction photocell A photoconductive or photo-
JTAC Abbreviation of Joint Technical Advisory voltaic cell that is essentially a light-sensitive
Committee. JUNCTION DIODE.
judder In facsimile transmission, distortion caused junction point 1. A point at which two or more
by movements of the transmission or reception conductors, components, or circuits join in an
equipment. electrical connection. 2. The point in a computer
juice Colloquialism for electric voltage or current. routine at which one of several choices is made.
jukebox An automatic phonograph (usually found junction rectifier A semiconductor rectifier that
in public places) that contains a large assortment is, in effect, a heavy-duty junction diode, or the
of records. equivalent of several heavy-duty junction diodes
Juliet Phonetic representation for the letter J, in combination.
used in voice communications. junction station A microwave relay station joining
jump 1. To purposely provide a short circuit one or more microwave radio legs to the main
around some component or circuit. 2. Also called route or through route.
branch. In digital computer operations, a pro- junction transistor A transistor in which the emit-
gramming instruction specifying the memory lo- ter and collector consists of junctions (see JUNC-
cation of the next instruction and directing the TION, 2) between p and n semiconductor regions.
computer to it. Compare POINT-CONTACT TRANSISTOR.
jump, conditional See CONDITIONAL BRANCH. junctor In a crossbar system, a circuit that bridges
jump, unconditional See UNCONDITIONAL frames of a switching unit and terminates in a
BRANCH INSTRUCTION. switching device on each frame.
jumper A short piece of wire (usually flexible, insu- Jungian-world theory The theory that societies
lated, and equipped with clips) for jumping a keep repeating the same mistakes, generation af-
component or circuit. See JUMP, 1. ter generation. Of interest to some researchers in
jump instruction See BRANCH INSTRUCTION. artificial intelligence. It has been suggested that
junction 1. A joint (connection) between two con- supercomputers might help find solutions to re-
ductors. 2. The region of contact between semicon- curring social problems.
ductor materials of opposite type (e.g., pn junction). justification 1. The alignment of text along the left
3. A waveguide fitting used to attach a branch margin, the right margin, or both margins. 2. A
waveguide to a main waveguide at an angle. method of altering the speed of a digital signal so
junction barrier See DEPLETION REGION. that it can be received by equipment designed for
junction battery A nuclear battery in which a sili- a different data speed. The rate of speed is lower
con pn junction is irradiated by strontium 90. after this process is applied. Also called pulse
junction box A (usually metal) protective box or stuffing.
can into which several conductors are brought to- justify 1. To adjust the printing of words for
gether and connected. aligned left and/or right margins. 2. In computer
junction capacitance In a semiconductor pn junc- operations, to shift an item in a register so that
tion, the internal capacitance across the junction; the most- or least-significant digit is at the corre-
it is of special interest when the junction is re- sponding end of the register.
verse-biased. Also called barrier capacitance. just-operate value The current or voltage level at
junction capacitor See VOLTAGE-VARIABLE CA- which a relay or similar device just closes. Also
PACITOR. called just-close value.
junction diode A semiconductor diode created by just-release value The current or voltage level at
joining an n-type region and p-type region as a which a relay or similar device just opens. Also
wafer of semiconductor material, such as germa- called just-open value.
nium or silicon. just scale A musical scale of three consecutive tri-
junction field-effect transistor Abbreviation, ads, the highest note of each being the lowest
JFET. A field-effect transistor in which the gate note of the next. Each triad has the ratio 4:5:6 or
electrode consists of a pn junction. 10:12:15.
junction filter A combination of separate low- and jute Tar-saturated fiber, such as hemp, used as a
high-pass filters having a common input, but protective covering for cable.
separate outputs. The filter is used to separate jute-protected cable A cable whose outer covering
two frequency bands and transmit them to differ- is a wrapping of JUTE or similar material.
ent circuits. juxtaposed elements Components placed or
junction laser See LASER DIODE. mounted side by side.
junction light source See LIGHT-EMITTING juxtaposed images Images (e.g., those on the
DIODE. screen of a dual-beam cathode-ray tube) that are
junction loss 1. The loss that occurs in a tele- close to each other for simultaneous viewing, but
phone circuit at connecting points. 2. Loss in a do not overlap at any point.
K electron In certain atoms, one of the electrons
K 1. General symbol for CONSTANT. 2. Symbol for
whose orbit is nearest the nucleus.
POTASSIUM. 3. Symbol for KELVIN. 4. Radiotele-
Kel-f Abbreviation of polymonochlorotrifluor-
graph symbol for go ahead or over. 5. Symbol for
ethylene, a high-temperature insulating material.
CATHODE. 6. Symbol for KILOBYTE. 7. Abbrevi-
Kellie bond 1. The junction of two mated electri-
ation of KILOHM (k is preferred). 8. Abbreviation
cally conductive surfaces that are held together
of KILO-.
by an adhesive that exhibits negligible resistance
k 1. Abbreviation of KILO-. 2. Symbol for the
thermally and electrically when set. 2. To make a
BOLTZMANN CONSTANT. 3. General symbol for
thermally conductive joint, as from a heatsink to
a mathematical constant. 4. Symbol for DIELEC-
a chassis or component.
TRIC CONSTANT. 5. Abbreviation for KILOHM.
kelvin (Lord Kelvin, 1824“1907) Symbol, K. The SI
kA Abbreviation of KILOAMPERE.
unit of thermodynamic temperature; 1 K =
Karnaugh map A logic chart showing switching-
1/273.16, the thermodynamic temperature of the
function relationships and used in computer
triple point of water.
logic analysis to determine quickly the simplest
Kelvin absolute electrometer An electrostatic
form of logic circuit for a given function. The Kar-
voltmeter consisting of a movable metal plate (or
naugh map is sometimes regarded as a tabular
plates) and a stationary metal plate (or plates)
form of the Venn diagram.
Kansas City standard A frequency-shift modula-
tion standard for a computer/tape-recorder inter-
Pointer
face. Also called byte standard.
KB 1. Abbreviation of KEYBOARD. 2. Abbreviation Stationary
of KILOBYTE. plates
K band The 18- to 27-GHz band of frequencies,
Movable
pertaining to their use in radar applications.
plate
ac or dc
kcal Abbreviation of KILOCALORIE.
input
K carrier system A four-wire carrier-current tele-
phone system using frequencies up to 60 kHz
and providing 12 channels.
kCi Abbreviation of KILOCURIE.
kcs Abbreviation of kilocharacter per second (1000
characters per second).
K display See K SCAN.
Spiral
KDP Abbreviation of POTASSIUM DIHYDROGEN
springs
PHOSPHATE, a ferrolelectric material.
keeper A small iron bar placed across the poles of
a permanent magnet to forestall demagnetization. Kelvin absolute electrometer


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390 Kelvin absolute electrometer • keyboard keyer


between which voltage is applied. The movable Kennelly-Heaviside layer (A.E. Kennelly, 1861“
plate(s) is displaced over a distance that is pro- 1939; Oliver Heaviside, 1850“1925) An early
portional to the potential, against the torque of a name for ionized regions in the upper atmo-
return spring. sphere. These regions reflect and refract radio
Kelvin balance An apparatus for measuring cur- waves at certain frequencies. There are several
rent in terms of magnetic pull. A coil is attached layers at various altitudes. Also see IONO-
to each end of the beam of a balance, and coils SPHERE and IONOSPHERIC LAYERS.
ride directly above two stationary coils. Current keraunograph A meteorological instrument for de-
flows through all coils, making one pair attractive tecting distant electrical storms. In its simplest
and the other repellent, thus unbalancing the form, it consists of a galvanometer connected in
beam. Balance is restored by sliding a weight series with an antenna and ground.
whose position along a graduated scale indicates keraunophone A radio-receiving KERAUNO-
the current strength. GRAPH.
Kelvin contacts Electrical contacts designed to kernel Inside an electrical conductor, a line along
eliminate the effect of lead resistance on the accu- which the magnetic field strength is zero. Gener-
racy of measurement. Two leads run to each test ally, this line is near the center of the conductor.
point, one lead carrying the test signal and the Kerr cell A nitrobenzene-filled cell that makes use
other leading directly to the measuring instrument. of the KERR ELECTRO-OPTICAL EFFECT. It can
Kelvin double bridge A special bridge for measur- function as an electric light shutter or control.
ing very low resistance (0.1 ohm or less). The ar- Kerr electro-optical effect The tendency of cer-
rangement of the bridge reduces the effects of tain dielectric materials to become double-
contact resistance that causes significant error refracting in an electric field.
when such low resistances are connected to con- Kerr magneto-optical effect The tendency of
ventional resistance bridges. glass and some other solids and liquids to be-
come double-refracting in a magnetic field.
Kerst induction accelerator See BETATRON.
keV Abbreviation of KILOELECTRONVOLT.
Kew magnetometer A special magnetometer used
to measure the intensity of the earth™s magnetic
field, and also the magnetic declination at a given
point on the earth™s surface. The device is de-
R1 R2 signed for very high accuracy, using magnifying
lenses.
M
key 1. See DECRYPTION KEY. 2. A projection or
pin that guides the insertion of a plug-in compo-
nent into a holder or socket. 3. A digit or digits
used to locate or identify a computer record (but
When R1/R2 = R3/R4,
R3 R4 not necessarily part of the record). 4. A special-
Rx = (R1/R2)Rs
ized hand-operated switch, used to make and
Rx Rs
break a circuit repetitively to form the dot and
dash signals of Morse code telegraphy. Primarily
of historical interest. Used by some amateur ra-
dio operators for hobby purposes. 5. Slang for
Kelvin double bridge principal or main.
keyboard An array of lettered or numbered, low-
torque push buttons, used to enter information
Kelvin replenisher A static generator consisting of
into a computer, telegraph, teletypewriter, or au-
two pairs of concentric, rotating semicircular
tomatic control system.
conductors connected to brushes. The machine
keyboard computer A digital computer in which
can be regarded as a rotating electric doubler.
the input device is an electrical keyboard of the
Kelvin scale See ABSOLUTE SCALE.
typewriter or calculator type.
Kelvin temperature scale See ABSOLUTE SCALE.
keyboard entry The operation of a keyboard to en-
Kelvin voltmeter An electrostatic voltmeter in
ter information into a computer for processing.
which an assembly of figure-8-shaped metal
keyboard keyer A device for automatically sending
plates rotates between the plates of a stationary
Morse code using a typewriter-like keyboard,
assembly when a voltage is applied between the
rather than a paddle or straight key. Each key on
assemblies. The length of the arc of rotation is
the keyboard, when pressed, produces the com-
proportional to the electrostatic attraction and,
plete character and a space following it. Most key-
thus, to the applied voltage.
board keyers have buffers to allow typing well
Kendall effect Distortion in a facsimile record
ahead of the code being sent, with insertion of all
caused by unwanted modulation produced by a
the correct spaces. The speed range is usually
carrier signal.
391
keyboard keyer • keying speed


from about 5 words per minute (wpm) to 60 or 70 keyer An automatic device for keying a radiotele-
wpm, although some keyboard keyers are pro- graph transmitter or wire telegraph circuit. The
grammed for speeds over 100 wpm. keyer can operate from perforated tape, an em-
keyboard lockout A keyboard interlock in a data bossed disk, magnetic tape, or other similar
transmission circuit that prevents data from be- recording.
ing transmitted while the transmitter of another keyer adaptor A modulated-signal detector that
station on the same circuit is operating. produces a direct-current signal having an ampli-
keyboard send-receive unit A teletypewriter lack- tude sympathetic with the modulation; it pro-
ing an automatic input device. vides the keying signal for a frequency-shift
key cabinet In a telephone system, a facility that exciter in radio facsimile transmission.
shows a subscriber which lines are busy and key escrow A controversial system in which the
which lines are open. government is provided with certain components
key chirp A chirping sound in a received signal, re- of decryption keys to all communications ciphers,
sulting from slight frequency shift when a ra- according to laws that would allow the govern-
diotelegraph transmitter is keyed. It does not ment to eavesdrop on private communications or
occur with a well-designed transmitter. transactions after getting a court order. The key
key-click filter An inductance-capacitance (LC) or components are held in a secure place, that is, in
resistance-capacitance (RC) filter for smoothing a “escrow,” unless and until the necessary court or-
keying wave to eliminate KEY CLICKS. It func- der is obtained. See DECRYPTION KEY.
tions by optimizing the rise and decay times of keying 1. The modulation of a carrier by switching
the keyed waveform. it on and off. It is commonly used in radiotelegra-
key clicks Excessive bandwidth of a radiotele- phy. 2. The modulation of a carrier by switching
graph signal that can result when a keyed signal its frequency between two defined values. It is
has rise and decay times that are too rapid. Pro- also called FREQUENCY-SHIFT KEYING (FSK)
duces characteristic clicking or popping sounds, and it is used in data transmission. 3. The mod-
with resulting interference, in receivers tuned to ulation of a carrier with an audio tone that is
frequencies near that of the transmitted signal. A switched on and off. The carrier can be modu-
KEY-CLICK FILTER can eliminate this. lated via amplitude modulation (AM), frequency
modulation (FM), pulse modulation, or any other
form that will convey the audio tone. It is occa-
No click
sionally used in radiotelegraphy at very-high fre-
Click
produced
produced quencies (VHF) and above. Also called audio
keying. 4. The modulation of a carrier with an au-
Amplitude




dio tone whose frequency is switched between
two defined values. The carrier can be modulated
via amplitude modulation (AM), frequency modu-
Time
lation (FM), pulse modulation, or any other form
that will convey the audio tone. It is commonly
used in data transmission at VHF and above.
Also called AUDIO FREQUENCY-SHIFT KEYING
(AFSK).
key clicks
keying chirp A rapid change in the frequency of a
continuous-wave signal, occurring at the begin-
keyed AGC A controlled automatic gain control
ning of each code element. In the receiver, the re-
(AGC) system in a television receiver circuit. The
sulting sound is a chirp.
AGC acts when the horizontal sync pulse ap-
keying error rate In data transmission, the ratio
pears; it is inactive between pulses. This prevents
of incorrectly keyed signals to the total number of
unwanted actuation of the AGC by noise tran-
signals keyed.
sients and picture-signal elements.
keying filter See KEY-CLICK FILTER.
keyed clamp A clamping circuit that uses a con-
keying frequency 1. In audio-keyed radiotelegra-
trol signal to determine the clamping time.
phy, the audio frequency (tone) of the dot and
keyed interval In a transmission system that is
dash signals (as opposed to the carrier fre-
keyed periodically, an interval beginning with a
quency). 2. In radiotelegraphy, the transmission
change in state and having a duration of the
speed (see KEYING SPEED). 3. The number of
shortest time between changes in state.
times per second that a black-line signal occurs
keyed rainbow generator For testing of color-
while an object is scanned in a facsimile system.
television receivers, a signal generator that
keying monitor A simple detector used by an op-
produces a rainbow color pattern on the screen
erator to listen to the keying of a radiotelegraph
(i.e., a set of 10 vertical color bars representing
transmitter.
the spectrum, with blank bars in between). The
keying speed The speed (in words per minute) of a
pattern results from gating the 3.56-MHz oscillator
telegraph or radio-telegraph transmission.
in the receiver at a frequency of 189 kHz.
392 keying transients • kilogram-calorie


kg/m3 Symbol for KILOGRAMS PER CUBIC ME-
keying transients 1. Transients arising from the
TER, the SI unit of density.
keying of a radiotelegraph transmitter or wire
K-H layer See KENNELLY-HEAVISIDE LAYER.
telegraph circuit. 2. Transients that arise from
kHz Abbreviation of KILOHERTZ.
the repetitive making and breaking of any circuit.
kick 1. To place into sudden operation, as by the
keyless ringing In a telephone system, ringing
quick, forcible closure of a switch or the rapid ap-
that begins as soon as the calling plug is put in
plication of an enabling pulse. 2. See TRIGGER.
the appropriate jack on the jack panel.
3. Colloquialism for an abrupt, momentary elec-
key pulse In telephone operations, a signaling sys-
tric shock.
tem in which the desired numbers are entered by
kickback 1. The counter EMF that appears across
pressing corresponding pushbuttons or keys.
an inductor when current is interrupted. 2. See
key punch A keyboard-operated machine for
FLYBACK.
recording information by perforating a tape or
kickback power supply A high-voltage power sup-
cards.
ply using the flyback principle. See FLYBACK.
keyshelf A shelf that supports manually operated
kidney joint A waveguide coupling used in radar.
telephone switchboard keys.
The joint is flexible, or can consist of an air gap,
key station The master (control) station in a com-
to allow rotation of the antenna.
munications or control network.
Kikuchi lines A characteristic spectral pattern
keystoning A form of video image distortion in
produced by the electrons scattered when an
which the top of the picture is wider than the bot-
electron beam strikes a crystal.
tom, or vice versa. Thus, the image area is shaped
killer 1. A pulse or other signal used to disable a
like a trapezoid, rather than a rectangle.
circuit temporarily (e.g., a blanking pulse). 2. In
personal computing, an application of such im-
portance that it alone serves as the motivation for
someone to purchase or upgrade a system. Com-
mon examples are word processing and online
communications.
killer circuit 1. A circuit that disables some
TV function of a system, such as the audio in a
picture television receiver. 2. The blanking circuit in a
radar receiver. 3. A circuit that prevents re-
sponses to side-lobe signals in a repeater or
transponder.
Kilo Pronunciation, KEY-low. Phonetic alphabet
code word for the letter K.
kilo- Abbreviation, K or k. 1. A prefix meaning
thousand(s). 2. In digital data applications, a pre-
fix meaning 210 (1024).
keystoning kiloampere Abbreviation, kA. A unit of current
equal to 1000 amperes.
kilobit A unit of digital data equal to 210 (1024)
key switch 1. A lockable switch that is operated by
bits. Also see BIT.
inserting and turning a key in it. 2. A switch hav-
kilobyte Abbreviation, K or KB. A unit of digital
ing a long handle that transmits motion to the
data equal to 210 (1024) bytes. Also see BYTE.
mechanism through a cam. 3. See KEY, 1. 4.
kilocalorie Abbreviation, kcal. A large unit of heat;
The separate short-circuiting switch sometimes
1 kcal equals 1000 calories. See CALORIE.
mounted on the base of a telegraph key (see KEY,
kilocurie Abbreviation, kCi. A large unit of ra-
1). 5. A switch that actuates the keys of an elec-
dioactivity equal to 3.71 — 1013 disintegrations
tronic organ.
per second; 1 kCi equals 1000 curies. Also see
key-to-disk unit A keyboard-to-magnetic-disk
CURIE, MEGACURIE, MICROCURIE, and MILLI-
data-processing unit.
CURIE.
keyway A groove or slot into which a mating key
kilocycle See KILOHERTZ.
slides to position a plug-in component (see KEY,
kiloelectronvolt Abbreviation, keV. A large unit of
2).
electrical energy equal to 1000 electronvolts. See
keyword In information retrieval systems, the sig-
ELECTRONVOLT.
nificant word in the title describing a document
kilogauss A large unit of magnetic flux density;
(e.g., in the title “A Primer on French Cuisine,”
1 kilogauss equals 1000 gauss or 0.1 tesla.
the word cuisine would be the keyword, the oth-
kilogram Abbreviation, kg. The SI base unit of
ers having no singular significance).
mass; it is equal to 1000 grams.
kg Abbreviation of KILOGRAM.
kilogram-calorie The heat required to raise 1 kilo-
kgC Abbreviation of KILOGRAM-CALORIE.
gram of water 1°C.
kgm Abbreviation of KILOGRAM-METER.
393
kilogram-meter • kite-supported antenna


kilogram-meter Abbreviation, kgm. A unit of me- kinescope recording A motion-picture or video-
chanical energy (work); 1 kgm is the energy re- tape made from the screen (or taken from the cir-
quired to raise a mass of 1 kilogram vertically by cuit) of a television picture tube.
a distance of 1 meter (equal to 7.2334 foot- kinetic energy The energy associated with parti-
pounds). Also see JOULE. cles, bodies, or electric charge carriers in motion.
kilohertz Abbreviation, kHz. A unit of frequency; kinetograph See KINEMATOGRAPH.
1 kHz equals 1000 Hz. kinetoscope A motion-picture projector.
kilohm Symbol, k„¦. A unit of high resistance, re- kiosk A computer and peripherals set up for the
actance, or impedance; 1 k„¦ equals 1000 ohms. purpose of multimedia use by the general public.
kilojoule Abbreviation, kJ. A unit of energy or It generally uses a touch screen for inputting data
work; 1 kJ equals 1000 joules. See JOULE. and must be ruggedly constructed to tolerate
kilolumen Abbreviation, klm. A unit of luminous rough treatment.
flux equal to 1000 lumens. See LUMEN. Kirchhoff™s first law The sum of the currents flow-
kilomega- See GIGA-. ing out of a point in a direct-current circuit
kilomegahertz See GIGAHERTZ. equals the sum of the currents flowing into that
kilometer Abbreviation, km. A large metric unit of point.
linear measure; 1 km equals 1000 meters (3280.8 Kirchhoff™s laws (Gustav Robert Kirchhoff, 1824“
feet). 1887) Two laws of electric circuits that account
kilo-oersted Abbreviation, kOe. A unit of magnetic for the behavior of certain networks. See KIRCH-
field strength; 1 kOe equals 1000 oersteds. See HOFF™S FIRST LAW and KIRCHHOFF™S SECOND
OERSTED. LAW.
kiloroentgen Abbreviation, kr. A large unit of ra-
dioactive radiation; 1 kr equals 1000 roentgens.
First law: I1 + I2 + I3 = I4 + I5
See ROENTGEN.
kilorutherford Abbreviation, krd. A large unit of ra-
dioactivity equal to 109 disintegrations per second.
kilovar A compound term coined from kilo- and
I4 I5
VAR (the abbreviation of volt-amperes reactive). It
x
is equal to a reactive power of 1000 watts.
kilovar-hour A large unit of reactive electrical en-
ergy, equivalent to 1000 reactive watts mani-
fested for a period of one hour. I1 I2 I3
kilovolt Abbreviation, kV. A unit of high voltage;
1 kV equals 1000 V.
kilovolt-ampere Abbreviation, kVA. A unit of high
power that gives the TRUE POWER in a direct- Second law: V1 + V2 + V3 + V4 = V5
current circuit and the APPARENT POWER in an
alternating-current circuit; 1 kVA equals 1000 W.
V1 V2
Also see DC POWER.
kilovolt-ampere reactive See KILOVAR.
kilovoltmeter A voltmeter designed to measure V3 V4
thousands of volts (kilovolts). V5
kilowatt Abbreviation, kW. A unit of high power;
1 kW equals 1000 watts. Also see WATT. Kirchhoff™s laws
kilowatt-hour Abbreviation, kWh. A common unit
of electrical energy; 1 kWh equals 1000 watt
hours, or the equivalent of 1000 watts dissipated Kirchhoff™s second law The algebraic sum of all
for a period of one hour. Also see ENERGY, the voltage drops around a direct-current circuit
KILOWATT-HOUR, POWER, WATT-HOUR, and (including supply voltages) is always equal to
WATT-SECOND. zero.
kilowatt-hour meter A motorized meter for kit A selection of components, associated equip-
recording (electrical) power consumption in kilo- ment, supplies (such as wire and hardware), and
watt-hours. Also see KILOWATT-HOUR. instructions for constructing a piece of electronic
kinematograph A motion picture camera. Also equipment.
called CINEMATOGRAPH and KINETOGRAPH. kite-supported antenna A longwire antenna that
kine 1. See KINESCOPE, 1. 2. See KINESCOPE uses a kite as a support for the far (nonstation)
RECORDING. end. A tether is used to reduce the chance that
kinescope 1. The picture tube in a television re- the kite will fly away with wire attached. It was
ceiver. 2. See KINESCOPE RECORDING. used by Marconi in early experiments with radio.
kinescope recorder A film or tape apparatus for Radio amateurs and shortwave listeners some-
recording television pictures. times use this scheme at low and medium
394 kite-supported antenna • Kramer system


frequencies. It is a dangerous antenna because of knife-edge diffraction The lessening of atmo-
electrostatic buildup, a tendency to attract light- spheric signal attenuation when the signal
ning, the possibility of its breaking loose, and the passes over a sharp obstacle and is diffracted.
risk that it might contact utility lines. knife switch A switch composed of one or more flat
kJ Abbreviation of KILOJOULE. blades roughly resembling knife blades, which
k-line programming A method by which an artifi- are slid firmly between the jaws of pinching con-
cially intelligent robot can learn as it does a job, tacts to close a circuit.
so it will have an easier time doing the same job knob 1. A (usually round and insulated) finger dial
in the future. The robot controller actually learns for adjusting a variable electronic component,
from the robot™s mistakes. such as a potentiometer, variable capacitor, or
Klipsch horn A loudspeaker that includes a folded rotary switch. 2. A solid round insulator usually
low-frequency horn housed in a corner enclosure. having a low diameter to height ratio. 3. A small
klm Abbreviation of KILOLUMEN. ball- or rod-shaped electrode or protuberance.
kludge 1. A crude, useless, or grossly inefficient knocker A fire-control radar subassembly of syn-
machine or process. 2. A hastily contrived proto- chronizing and triggering circuits.
type of a circuit or device, put together for the knockout An area in a metal box or chassis that is
purpose of testing a concept, but not intended as easily removed by tapping or knocking to provide
a representative of a production unit. an opening.
klydonograph A device that photographically knot A unit of speed, corresponding to 1 nautical
records the voltage gradient in the presence of an mile per hour. A speed of 1 knot is about 1.15
electric field. statute miles per hour; a speed of 1 statute mile
klystron A microwave tube whose operation is per hour is about 0.868 knots. It is used by
based on the velocity modulation of an electron mariners for specifying speeds at sea, and also
beam by buncher and cavity reentrant cavities. occasionally by meteorologists in specifying wind
speeds.
knowledge The data in a computer and in mass-
Coupling loop Terminals storage media, accumulated over time and capa-
Drift space
ble of being put to practical use.
Input Output
Buncher
Catcher kOe Abbreviation of KILO-OERSTED.
Kolster decremeter An absorption wavemeter
Collector
with a movable scale; it permits measurement of
Heater the decrement of a radio wave.
Kooman antenna A unidirectional antenna con-
Glass
Grid sisting of stacked, full-wave, center-fed driven el-
Cathode ements, and a reflecting screen.
Metal
Korner Killer Trade name for an acoustically ab-
Feedback path sorbent object that reduces sound echoes that
can occur in enclosed rooms. The name results
klystron because the device works best when placed in a
corner (where two walls meet).
Kovar An alloy of cobalt, iron, and nickel. It is used
klystron amplifier A microwave amplifier using a
mostly in glass-to-metal seals because it has
klystron.
characteristics of both kinds of material.
klystron harmonic generator A frequency-
Kozanowski oscillator A positive-grid vacuum-
multiplying power amplifier using a klystron. It is
tube UHF oscillator circuit using two tubes
used at microwave radio frequencies.
having cylindrical elements, and a pair of
klystron oscillator A klystron operated as a self-
parallel-wire tanks.
excited microwave oscillator.
Kr Symbol for KRYPTON.
klystron repeater A microwave amplifier in which
kr Abbreviation of KILOROENTGEN.
a klystron inserted in a waveguide boosts the am-
K radiation X rays emitted from an atom when an
plitude of an incoming signal.
electron becomes a K electron.
km Abbreviation of KILOMETER.
kraft paper Strong brown paper used for insula-
knee 1. A sharp bend in a response curve for a de-
tion and as the dielectric of paper capacitors.
vice, usually indicating the onset of conduction,
Kramer system A system of three-phase motor
saturation, cutoff, pinchoff, or limiting action. It
control providing constant horsepower, and
applies especially to semiconductor diodes and
having a direct-current (dc) motor coupled to the
transistors. 2. The characteristics of a device
shaft of a wound-rotor three-phase induction mo-
when it is operated at a point in the vicinity of a
tor. The dc supply for the motor also supplies a
sharp bend in its response curve.
rotary converter. The speed-control rheostat is
knee noise Electrical noise generated by rapidly
connected in series with the field of the motor and
repeating current fluctuations at the knee in a
the dc power supply.
Zener diode.
395
Kraus antenna • kWh


ton is present in trace amounts in the earth™s at-
V1
RFC1 mosphere.
Plate wire K scan In radar operations, a modified A-scan
used in aiming antennas in which two pips are
RFC2 Cathode wire displayed; their relative amplitudes indicate the
antenna-aiming error.
C1 K series A series of spectral lines for the shortest
B+ wavelengths of radiation from the innermost elec-
Cathode wire tron shell of a radiating atom.
RFC5
KSR Abbreviation of keyboard send-receive unit.
RFC3 C2
Ku band A band of microwave frequencies between
Plate wire
approximately 12 and 18 GHz.
Kundt™s law The index of refraction of a medium
RFC4 C’ does not change continuously with wavelength in
V2
+’ the absorption bands.
A Kundt tube A device used to measure the speed of
sound in gases under various conditions. Sus-
Kozanowski oscillator pended particles in the gas form standing waves
that can be easily seen. Knowing the frequency of
the disturbance and the distance between nodes
of the standing waves, the speed can be deter-
Kraus antenna A bidirectional, flat-top beam an-
mined. The pressure and density of the gas, as
tenna consisting of a pair of closely spaced
well as temperature and humidity, affect the
dipoles. Several such sections can be connected
speed.
in series by crisscrossing the wires at voltage
kurchatovium See RUTHERFORDIUM.
loops.
kV Abbreviation of KILOVOLT.
krd Abbreviation of KILORUTHERFORD.
kVA Abbreviation of KILOVOLT-AMPERE.
Kryptol A mixture of clay, graphite, and silicon
kVAR Abbreviation of REACTIVE KILOVOLT-
carbide. It is used in electric heater elements be-
AMPERE.
cause of its low resistance and high melting
kVARh Abbreviation of KILOVAR-HOUR.
point.
kW Abbreviation of KILOWATT.
krypton Symbol, Kr. An inert, gaseous element.
kWh Abbreviation of KILOWATT-HOUR.
Atomic number, 36. Atomic weight, 83.80. Kryp-
Y
FL
AM
L 1. Symbol for INDUCTANCE. 2. Symbol for laboratory power supply A regulated direct-
MEAN LIFE. 3. Abbreviation of LOW. 4. Resem- current source whose adjustable output is less
bling the capital letter L in physical shape. than 10 kV at no more than 500 W.
TE

5. Symbol for LAPLACE TRANSFORM. laboratory standard See PRIMARY STANDARD
l 1. Symbol for LENGTH. 2. Abbreviation of LITER. and SECONDARY STANDARD.
3. Subscript for LOW. 4. Abbreviation of LUMEN; labyrinth speaker A loudspeaker whose enclosure
also abbreviated lm (preferred) and lum. (a wooden cubicle) includes a folded pipe or
La Symbol for LANTHANUM. acoustic transmission line (behind the speaker);
label 1. A symbolic group of characters that identi- the inner walls are lined with a sound-absorbent
fies an area of memory, an item of data, a file, or material. When the pipe, which is open-ended, is
a record. 2. A name assigned to a source program half as long as the wavelength of the frequency
instruction step to identify the step as a coding being reproduced, the sound emerging from the
entry point, or to make the step usable as a refer- open end is in phase with that radiated by the
ence point for entry to the routine or subroutine front of the speaker and, therefore, reinforces it.
in which it appears. laced wiring Circuit wiring in which wires or ca-
label group A collection of labels, usually of the bles run parallel in bundles that are tied together
same type, held in an operating system. with LACING CORD.
label identifier Within a label, a character set lacing cord Strong, sometimes waxed cord used to
used to name the kind of item labeled. tie together wires running parallel in a bundle.
label record A record identifying a file recorded Also see LACED WIRING.
on a magnetic storage medium (e.g., magnetic lacquer disk See CELLULOSE-NITRATE DISK.
tape). lacquer-film capacitor A fixed capacitor with a
label set A collection of labels having a common la- plastic film dielectric; the film is applied as liquid
bel identifier. lacquer to the metal foil.
labile oscillator A frequency-controlled local oscil- lacquer master A master recording made on a
lator. CELLULOSE-NITRATE DISK.
laboratory conditions The environmental, me- lacquer original See LACQUER MASTER.
chanical, and electrical parameters characteristic ladar Abbreviation of LASER DOPPLER RADAR.
of controlled conditions. Actual operating condi- Also abbreviated lopplar.
tions can be much different. ladder attenuator See LADDER-TYPE ATTENUA-
laboratory-grade instrument An instrument hav- TOR.
ing the high accuracy and stability that suit it to ladder filter A form of delay line or filter. It gener-
precision measurements in a laboratory. Also ally consists of series and parallel impedances,
called PRECISION INSTRUMENT. Compare either in a balanced or unbalanced form.
SERVICE-TYPE INSTRUMENT. ladder line See AIR-INSULATED LINE.


Copyright © 2001 by The McGraw-Hill Companies, Inc.
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397
ladder network • lamp driver


ladder network A network consisting of several L lag network A phase-shifting circuit containing
sections in cascade. See L SECTION, 1, 2, 3. series-resistance and shunt-capacitance arms. It
ladder-type attenuator An attenuator consisting produces a lagging phase shift. Compare LEAD
of a ladder network equipped with a switching NETWORK.
circuit for selecting the output at various sec- lambda wave An electromagnetic disturbance that
tions. travels along the surface of an object. An example
is the surface wave characteristic of low-
frequency propagation.
lambert Symbol, L. The centimeter-gram-second
(cgs) unit of luminance, equal to the brightness of
an ideal diffusing surface that radiates or reflects
light at 1 lumen per square centimeter. The SI
(preferred) unit of luminance is the candela per
square meter (cd/m2); 1 lambert equals 104
cd/m2. Also see CANDELA.
Input Output
Lambert™s law of illumination The illumination
of a surface by a point light source is inversely
proportional to the square of the distance be-
ladder-type attenuator
tween the surface and the source. If the surface
is not perpendicular to the rays, the illumination
LAFOT Coded weather broadcasts aired every six is proportional to the cosine of the angle of inci-
hours by the U.S. Weather Bureau through ma- dence.
rine radiotelephone broadcasting stations for the laminated armature An armature for a motor or
Great Lakes region. generator, made of stacked laminations.
lag In computations relating the phase of alternat- laminated contact A switch contact consisting of
ing-current signals, the extent to which one a number of laminations”each contacting a con-
quantity follows another in time (e.g., the current ducting counterpart.
lags the voltage by 90 degrees in a pure inductive laminated core A core for a transformer, choke, re-
reactance). Compare LEAD. lay, or similar device, made of stacked laminations.
laminated disk A layered recording disk.
laminated pole A pole within a motor, generator,
relay, electromagnet, or similar device, made of
stacked laminations.
lamination 1. A relatively thin sheet of metal cut
to a required shape to be stacked with other sim-
ilar sheets to form a laminated core or pole. 2. A
relatively thin sheet of plastic that is bonded to-
gether and heat-formed with other similar sheets
to produce a sheet or piece of desired thickness
and strength.
lamp A device for converting electrical energy into
visible light. The term includes a number of de-
vices (e.g., arc lamp, fluorescent tube, incandes-
cent lamp, mercury-vapor lamp, and neon
bulb).
lamp-bank resistor A makeshift heavy-duty re-
sistor consisting of several incandescent lamps
arranged so that they can be switched in vari-
ous series, parallel, and series-parallel combi-
nations to vary the resistance provided by the
filaments.
lampblack Carbon obtained from soot deposited
by a smoky flame. The substance is used as the
basic material for some resistors.
lagged-demand meter A meter with a built-in time lamp cord A two-wire insulated cord, used with
delay. low-wattage alternating-current appliances at
lagging current Current that follows voltage (in 117 volts. The wire is usually stranded copper
time). Also see LAG. equivalent to American Wire Gauge (AWG) #16.
lagging load A load in which current lags behind lamp dimmer See DIMMER.
voltage (i.e., an inductive load). Compare LEAD- lamp driver A usually single-stage circuit for am-
ING LOAD. plifying a small pulse to drive an indicator lamp.
398 lamp extractor • Laplace transform


lamp extractor A special tool used to insert or ex- charged probe inserted into the positive column.
tract miniature lamps for electronic equipment. Compare CROOKES™ DARK SPACE.
lamp jack A receptacle with a spring release that Langmuir™s law See CHILD™S LAW.
holds a small incandescent bulb. The bulb is re- language In digital-computer operations, any one
moved and replaced by pushing and twisting. of the detailed systems for representing data, in-
structions, and procedures through the use of
symbols and symbol sequences. See MACHINE
LANGUAGE, ASSEMBLY LANGUAGE, COBOL,
FORTRAN, and BASIC.
language laboratory An electronic contribution to
the teaching and learning of languages. It con-
sists of recordings in a language being studied
and all the equipment associated with recording,
playback, and monitoring. Students listen to the
speech of experts in the language record, listen
to, and later erase their own utterances in the
language.
language translation 1. The conversion of state-
ments in one computer language to equivalent
statements in another. 2. The conversion of one
written natural language into another (e.g., French
to Russian) by means of a computer program.
language translator 1. An assembly program,
lamp jack compiler, or other routine used for translation be-
tween computer languages. 2. A high-level pro-
lamp-type expander A volume expander in which gram that allows a computer to translate one
the tungsten filament in an incandescent lamp written natural language into another (e.g., Chi-
serves as the nonlinear resistor. nese to Italian).
lamp-type readout For counters, calculators, and L antenna See INVERTED-L ANTENNA.
digital meters, a readout device in which each lantern battery A moderate-sized electrochemical
digit is indicated by a lamp. battery usually rated at 6 volts. Derives its name
LAN Abbreviation of LOCAL AREA NETWORK. from its original use as a power source for portable
land 1. The flat, reflective surface between pits on lamps. One type has spring contacts on the top.
a compact disc (CD). Compare PIT, 1. 2. The thin Another type has thumbscrew terminals. The non-
vinyl wall between grooves on a phonograph rechargeable battery consists of 4 zinc“carbon
record. 3. A bonding point in a microcircuit. 4. or alkaline cells in series. Some varieties are
Pertaining to earthbound communications sta- rechargeable, consisting of nickel“cadmium (NiCd)
tions. or nickel“metal-hydride (NiMH) cells. This type of
Land camera See POLAROID CAMERA. battery can provide enough energy to operate a
landing beacon The aircraft landing-beam trans- low-power radio transceiver. Two units connected
mitter. Also see LANDING BEAM. in series, or four units in series-parallel, make a
landing beam A highly directional airport radio 12-volt battery that can power a small portable
signal beamed upward to guide aircraft landing Citizen Band (CB) or amateur radio station.
during conditions of poor visibility. lanthanum Symbol, La. An elemental metal of the
landline A telephone or telegraph circuit com- rare-earth group. Atomic number, 57. Atomic
pleted with wires. weight, 138.906.
landmark beacon Any beacon that is not an air- lanyard A wire or cable used to quickly pull apart
way or airport beacon. the halves of a quick-disconnect connector.
land mobile service Two-way radio service be- lap A device used for grinding piezoelectric crystals
tween a base station and mobile land vehicles, or for resonance at a desired frequency.
among mobile land vehicles. lap dissolve The simultaneous fading out of one
land mobile station A radio station aboard a mo- televised scene while another is fading in so that
bile, earthbound vehicle. one is apparently dissolving into the next. It is
land return Ground reflection of radar signals also applicable to motion pictures.
back to the transmitter. lapel microphone A small microphone that is
land station A fixed ground station. clipped to a lapel of a user™s jacket or coat.
Langevin ion An electrically charged particle, such lap joint An overlapping splice of two conductors.
as a grain of dust or droplet of water, resulting Laplace transform Symbol, L. An operator that re-
from the accumulation of ions. duces the work of solving certain differential
Langmuir dark space In a luminous gas dis- equations by permitting them to be handled by
charge, the dark region around a negatively simpler algebraic methods.
399
lapping • laser diode


lapping Fine-tuning quartz crystal plates by mov- Larmor orbit The path followed by a charged par-
ing them over a flat plate coated with a liquid ticle in a constant magnetic field. Because of in-
abrasive. teraction between the external field and the field
laptop computer See NOTEBOOK COMPUTER. generated by the particle, the charged particle
lap winding In a motor or generator armature, a travels in a circular path.
winding in which the opposite ends of each coil laryngaphone See THROAT MICROPHONE.
are connected to the adjoining segments of the LASCR Abbreviation of LIGHT-ACTIVATED SILI-
commutator. CON-CONTROLLED RECTIFIER.
lap wrap 1. A form of asbestos cloth wire insula- LASCS Abbreviation of LIGHT-ACTIVATED SILI-
tion. 2. A method of wrapping with electrical tape, CON-CONTROLLED SWITCH.
in which there is considerable overlap among the lase To emit coherent electromagnetic energy in
turns of the tape. the visible-light spectrum. See LASER.
large calorie See KILOGRAM-CALORIE. laser Acronym for light amplification by stimulated
large loop antenna A single-turn open or closed emission of radiation. A device that produces co-
loop, usually having a circumference of 0.5 wave- herent radiation in the visible-light range, that is,
length or 1 wavelength. With a half-wavelength between 750 and 390 nanometers (one nanome-
ter is 10-9 meter). Some devices that produce co-
open or closed loop, maximum radiation occurs
in the plane of the loop. A full-wavelength closed herent radiation in the infrared, ultraviolet, or
loop exhibits maximum radiation and response X-ray parts of the spectrum are also referred to as
along the axis. This type of antenna can be used lasers. Lasers can be either continuous or pulsed,
for wireless transmitting and receiving appli- and are characterized by coherent, monochro-
cations. Either the open or the closed half- matic emissions. The peak intensity ranges from
wavelength loop exhibits a slight power loss a few microwatts to many megawatts.
relative to a dipole, but the full-wavelength loop
shows a small gain over a dipole in its favored Flash
directions. Compare SMALL LOOP ANTENNA. tube
large-scale integration Abbreviation, LSI. The in-
clusion of more than 100 transistors, performing
various individual, but interrelated circuit func- Silvered
Laser Ruby rod end
tions, on a single integrated-circuit chip. beam
large signal A relatively high-amplitude signal that
traverses so large a part of the operating charac-
teristic of a device that nonlinear portions of the
characteristic are usually encountered. Compare
SMALL SIGNAL.
large-signal analysis The rigorous study of cir-
Power supply
cuits and devices that process large signals.
large-signal component 1. A coefficient or param-
eter such as amplification, transconductance, or
laser
dynamic resistance, measured under conditions
of large-signal operation. Also see LARGE SIGNAL
and LARGE-SIGNAL EQUIVALENT CIRCUIT. 2. A laser beam The radiation from a laser”especially
device designed for operation at high signal if the divergence is very low, that is, the rays are
levels. almost perfectly parallel, resulting in minimal di-
large-signal equivalent circuit For a given tran- vergence.
sistor circuit, the equivalent circuit at high signal laser-beam communication A form of coherent
levels (i.e., at amplitudes approaching saturation infrared or optical communication in which a
and cutoff levels). Also see EQUIVALENT CIR- laser beam is the link between transmitting and
CUIT. receiving stations. Also see LASER, LASER
large-signal operation The use of a circuit or de- DIODE, and LIGHT-BEAM COMMUNICATION.
vice at signal levels sufficiently high so that non- laser capacitor An energy-storage capacitor used
linear portions of the characteristic are usually to discharge-fire the exciter lamp of a laser. Also
encountered. Compare SMALL-SIGNAL OPERA- see LASER.
TION. laser cavity An optical-resonant cavity that results
large-signal transistor See POWER TRANSISTOR. in the emission of coherent light.
large-signal voltage gain In an integrated-circuit laser cutting A method of using a laser for sever-
amplifier, the voltage gain under open-loop condi- ing materials.
tions, determined as the difference in the output laser diode A special form of semiconductor light-
voltage divided by the difference in the input volt- emitting diode (LED), usually of the gallium-
age. It is usually specified in volts per millivolt or arsenide type, that emits coherent light when a
volts per microvolt. voltage is applied to its terminals. Also see LASER.
400 laser disk • laue diagram


+ latch-on relay See LOCKING RELAY.
P-type latchup In a transistor switching circuit, the ab-
material
normal condition in which the collector voltage
N-type remains at its switched-on level after the transis-
material tor is switched to cutoff from saturation.
latch voltage The input voltage at which a flip-flop
End
changes states.
mirror
late contacts Relay contacts that are operated fol-
lowing the movement of other contacts during the
Substrate and
relay™s operation.
heatsink
latency 1. The time taken by a digital computer to
deliver information from its memory. 2. In a serial
storage system, the access time less the word
’ time.
Output
latent image 1. In a storage tube, a stored image
that is not yet visible. 2. An image stored in the mo-
laser diode
saic of an iconoscope. 3. The image that will appear
when photographic film or paper is developed.
laser disk A method of reproducing sound in lateral chromatic aberration An aberration af-
which a laser is used to recover the sound from a fecting the sharpness of off-axis color television
compact disk. images.
laser Doppler radar Acronyms, ladar or lopplar. A lateral compliance In phonograph reproduction,
form of Doppler radar using the light beam of a the ease with which the stylus can move laterally
laser instead of radio waves. as it follows the groove. Also see COMPLIANCE
laser eye surgery A method of repairing the retina and LATERAL RECORDING.
of the eye without cutting the eyeball, using laser lateral-correction magnet In a color picture tube,
beams to push loose retina tissue back into a magnet operated with a set of pole pieces at-
place. tached to the focus element of the blue gun; it
laser gun A colloquial term for a weapon that controls horizontal positioning of the blue beam
makes use of a laser as a device of destruction. for convergence.
laser optical videodisc system A system in which lateral magnet See LATERAL-CORRECTION
a low-powered laser reads audio and video infor- MAGNET.
mation from a videodisc and delivers it to a televi- lateral recording A disc recording in which the
sion receiver. groove undulates from side to side. Compare
laser ranger A radar-like device using intense light VERTICAL RECORDING.
(instead of microwaves). latitude Abbreviation, lat. Angular distance mea-
laser show A three-dimensional, midair display sured around the earth™s circumference to the
having motion, made by using lasers in various north and south from the equator. Compare
combinations. LONGITUDE.
laser surgery The application of a laser in latitude effect The tendency of the earth™s mag-
medicine for the purpose of assisting in, or actu- netic field to decrease the number of charged
ally performing, operations on human subjects. subatomic particles that reach the surface of the
laser welding Welding (especially of tiny pieces) earth near the equator, as compared with the
with the heat produced by a laser beam. number reaching the surface at other latitudes.
lasing The emission of coherent electromagnetic Latour alternator See BETHENOD ALTERNATOR.
energy in the visible-light spectrum. See LASER. lattice 1. The orderly internal pattern (matrix) of
lat Abbreviation of LATITUDE. atoms in a crystal. Also see CRYSTAL LATTICE.
latch 1. A feedback loop in a symmetrical digital 2. A symmetrical arrangement of components in
circuit, such as a flip-flop, used to maintain a a network (such as an attenuator, a filter, or a
given state. 2. A simple logic-circuit storage ele- bridge circuit).

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