18WuD2x

diamond stylus • dielectric constant 183
diamond stylus A phonograph “needle” having as
its point a small, ground diamond.
diapason 1. Either of the two principal stops (open
and closed) of an electronic organ that cover the
entire range of the instrument. When one is used,
a note played is automatically sounded in several
octaves. 2. Tuning fork.
diaphony See DISSONANCE.
diaphragm A usually thin metal or dielectric disk
used as the vibrating member in headphones,
loudspeakers, and microphones, and as the pressure-sensitive
element in some sensors and
barometers.
diaphragm gauge A sensitive gas pressure gauge
using a thin metal diaphragm stretched flat. Increments
of pressure move the diaphragm,
relative to a nearby electrode, varying the
capacitance between the two.
diathermic Pertaining to a substance that efficiently
transfers heat or infrared energy.
diathermotherapy The use of diathermy in the
treatment of various physiological disorders.
diathermy 1. In medicine and physical therapy,
the production of heat in subcutaneous (below
the skin) tissues by means of high-frequency radio
waves. 2. A radio-frequency (RF) power oscillator
and associated equipment used to produce
heat in subcutaneous tissues.
diathermy interference Radio-frequency interference
(RFI) resulting from the operation of
unshielded and/or unfiltered diathermy equipment.
diathermy machine See DIATHERMY, 2.
diatomic Having two atoms (e.g., a DIATOMIC
MOLECULE).
diatomic molecule A molecule (such as that of
oxygen) composed of two atoms. Compare MON-
ATOMIC MOLECULE.
dibble A mathematical function in which a number
(usually an integer) is doubled, and then one is
added to the result. Thus, dibble n = 2n + 1.
dibit A combination of two binary digits (bits). The
four possible dibits are 00, 01, 10, and 11.
dice Plural of DIE, 1, 3.
dichotomizing search Also called binary search.
In digital computer operations, locating an item
in a table of items that are arranged by key values
in serial order. The required key is compared with
a key halfway through the table; according to this
relational test, half of the table is accepted and
again divided for comparison, etc. until the keys
match and the item is found.
dichotomy Characterized by the usually repetitive
branching into two sets, groups, or factions.
dichroism Also called dichromatism. 1. The property
of a crystal showing different colors,
depending on which axis corresponds to the line
of sight. 2. The property of a solid taking on different
colors as the thickness of the transmitting
layer changes. 3. The property of a liquid changing
color, according to solution concentration.
dichromate cell An electrolytic cell consisting of
electrodes of carbon and zinc. The zinc electrode
is immersed in a diluted solution of sulfuric acid,
and the carbon electrode in a solution of potassium
dichromate.
dicing The cutting of a semiconductor melt, crystal
wafer, or other material into dice (see DIE).
dictionary A table of specifications for the size and
format of computer file operands, and data
names for field and file types.
die 1. A small wafer of useful electrical material,
such as a semiconductor or a precision resistor
chip. 2. A casting designed to mold molten metal
into a specific configuration until the metal hardens.
3. Any small object of roughly cubical proportions.
4. To lose power or energy completely,
usually unintentionally. 5. In a computer program,
to produce unpredicted and useless results
following an initial run.
die bonding The bonding of dice or chips to a substrate.
die casting Making a casting by forcing molten
metal (such as an aluminum alloy, lead, tin, or
zinc) under high pressure into a die or mold.
dielectric A material that is a nonconductor of
electricity; especially, a substance that facilitates
the storage of energy in the form of an electric
field. Such materials are commonly used in capacitors
and transmission lines.
dielectric absorption The ability of certain dielectric
materials to retain some of their electric
charge—even after being momentarily shortcircuited.
Capacitors with this property must be
shorted out continuously for a certain length of
time before the dielectric has completely discharged.
dielectric amplifier A voltage amplifier circuit in
which the active component is a capacitor having
a nonlinear dielectric. A signal voltage applied to
the capacitor varies the capacitance, thus varying
the current. The modulated current flows
through a load resistor, developing an outputsignal
voltage higher than the input-signal voltage.
dielectric antenna An antenna in which some or
all of the radiating element is made of a dielectric
material, such as polystyrene. Primarily used at
microwave frequencies.
dielectric breakdown Sudden, destructive conduction
through a dielectric when the applied
voltage exceeds a critical value.
dielectric breakdown voltage The voltage at
which DIELECTRIC BREAKDOWN occurs in an
insulating material. Varies, depending on the
particular dielectric substance.
dielectric capacity See DIELECTRIC CONSTANT.
dielectric constant Symbol, k. For a dielectric material,
the ratio of the capacitance of a two-plate
capacitor using the dielectric material, to the capacitance
of the equivalent capacitor with dry air
as a dielectric. Also called inductivity and specific
inductive capacity.