18WuD2x

682 thermoelectric series • thin-film resistor
thermoelectric series A series of conducting metals,
sequenced so that if a thermocouple is made
from two of the metals, current flows at the hot
junction from the metal occurring earlier in the
series.
thermoelectron An electron emitted by a hot cathode.
Also see THERMION and THERMIONIC
EMISSION.
thermoelement A thermocouple, especially a
miniature one, used in a THERMOCOUPLE-TYPE
METER.
thermogalvanometer See THERMOCOUPLE
TYPE METER.
thermography A means of locating or mapping by
detecting infrared images. It can be in the form of
live video, similar to television, or in the form of
photographs, using infrared film. Many common
cameras can be used with infrared film to make
infrared photographs (thermographs).
thermojunction The junction of the two metals in
a thermocouple. A voltage appears when the dissimilar
metals are heated.
thermoluminescence Luminescence resulting
from the moderate heating of certain materials.
thermomagnetic effect The effects of temperature
on the magnetism of a body, or vice versa.
thermometer A (usually direct reading) device for
measuring temperature. Also see ELECTRONIC
THERMOMETER and THERMOMETER SCALE.
thermometer scale The scale on a thermometer,
graduated in degrees, from which temperature is
read. For a description of different scales, see
ABSOLUTE SCALE, CENTIGRADE SCALE,
FAHRENHEIT SCALE, REAUMUR SCALE, and
RANKINE SCALE. The Kelvin scale is the same as
the absolute scale, and the Celsius scale is the
same as the centigrade scale.
thermonuclear reaction A nuclear reaction in
which energy is released when lighter atoms are
converted into heavier atoms at temperatures in
the millions of degrees Celsius. Also see FISSION,
FUSION, and NUCLEAR REACTOR.
thermopile A device consisting of two or more
thermocouples connected in series for increased
voltage output.
thermoplastic material A plastic that can be resoftened
by applying heat after having been
molded into a desired shape. Example: polystyrene.
Compare THERMOSETTING MATERIAL.
thermorelay See THERMOSTAT.
thermosensitivity Sensitivity of a circuit or device
to heat.
thermosetting material A plastic that cures
chemically (will not ordinarily soften again when
heat is applied) after having been heat-molded
into a desired shape. Example: Bakelite. Compare
THERMOPLASTIC MATERIAL.
thermostat A temperature-sensitive switch. In one
common form, a movable contact is carried by a
strip of bimetal and the stationary contact is
mounted nearby.
thermostatic switch See THERMOSTAT.
thermoswitch See THERMOSTAT.
theta wave A form of brain wave that occurs at
extremely low frequencies, and is associated with
sleep or mental incoherence.
Thevenin’s theorem The proposition that, with
reference to a particular set of terminals, a network
containing a number of generators and constant
impedances can be simplified to a single
generator in series with a single impedance.
The equivalent circuit will deliver to a given load,
the same current, voltage, and power delivered by
the original network. Compare COMPENSATION
THEOREM, MAXIMUM POWER TRANSFER THE-
OREM, NORTON’S THEOREM, RECIPROCITY
THEOREM, and SUPERPOSITION THEOREM.
thick film A film of selected material (conductive,
resistive, dielectric, etc.) applied to a substrate by
painting, photography, or similar process. See,
for example, PRINTED CIRCUIT. Compare THIN
FILM. Typically, thick films are 1 mil or more in
thickness.
thick-film component A unit, such as a capacitor
or resistor, fabricated by thick-film techniques.
See, for example, PRINTED COMPONENT. Also
see THICK FILM. Compare THIN-FILM COMPO-
NENT.
thick-film resistor A resistor fabricated by thickfilm
techniques. See, for example, PRINTED
RESISTOR. Also see THICK FILM. Compare
THIN-FILM COMPONENT.
thick magnetic film See MAGNETIC THICK FILM.
thin film An extremely thin layer (less than 1 mil)
of a selected material (conductive, resistive, semiconductive,
dielectric, etc.) electrodeposited or
grown on a substrate. Compare THICK FILM.
thin-film capacitor A capacitor made by electrodepositing
a thin film of metal on each side of
a grown layer of oxide, as in an integrated circuit.
Also see THIN FILM.
thin-film component A unit (such as a capacitor,
resistor, diode, or transistor), fabricated by thinfilm
techniques. Also see THIN FILM. Compare
THICK-FILM COMPONENT.
thin-film integrated circuit An integrated circuit
in which the components and “wiring” are produced
by depositing (or growing) and processing
materials on a semiconductor slab or wafer (the
substrate). Compare HYBRID INTEGRATED CIR-
CUIT and MONOLITHIC INTEGRATED CIRCUIT.
thin-film memory In a computer, a storage meium
that is a magnetic thin film (see THIN FILM)
on a nonmagnetic substrate (often glass) and that
can be magnetized to represent digital data.
thin-film microelectronic circuit An integrated
circuit that occupies (essentially) two dimensions;
that is, a very thin integrated circuit.
thin-film resistor A resistor fabricated by thinfilm
techniques (see THIN FILM) (e.g., TANTA-
LUM-NITRIDE RESISTOR). Compare THICK-
FILM RESISTOR.