18WuD2x

y-axis • ytterbium metals 763
2. In a quartz crystal, the axis drawn perpendicular
to the faces of the hexagon.
y-axis amplifier See Y AMPLIFIER.
Yb Symbol for YTTERBIUM.
Y box See WYE BOX.
Y channel See Y AMPLIFIER.
Y-channel gain See Y GAIN.
Y circulator An interconnection among three
waveguides. When power is applied to the junction
through one waveguide, the wave is transferred
to the adjacent waveguide immediately to
the right or left.
Y connection See WYE CONNECTION.
y coordinate See ORDINATE.
Y current See WYE CURRENT.
Y-cut crystal A piezoelectric plate cut from a
quartz crystal in such a way that the plane of the
plate is perpendicular to the Y-axis of the crystal.
See CRYSTAL AXES and Y-AXIS, 2.
yd Abbreviation of YARD.
Y deflection Vertical deflection of the spot on the
screen of a cathode-ray tube. Compare X DE-
FLECTION.
Y diode The decoding diode in each of the Y lines of
a memory matrix. Compare X DIODE.
y direction The vertical direction in deflections
and in graphical presentations of data.
Y drive The driving source or energy for the y lines
of a computer memory matrix. Compare X DRIVE.
year Abbreviation, y or yr. The period of the earth’s
revolution around the sun, with respect to
distant stars: approximately 365.25 days or
3.15576 × 10 7 seconds.
Yellow Book A specialized format for compact-disk
read-only memory (CD-ROM) computer data storage
media, developed by Sony and Philips. It is
similar to RED BOOK, but it includes superior error
correction and storage capacity. See also CD-
ROM, GREEN BOOK, ORANGE BOOK, and RED
BOOK.
yellow copper ore See CHALCOPYRITE.
yellow metal A copper-zinc alloy that is 60% copper.
yellow pyrites See CHALCOPYRITE.
Y-equivalent circuit See WYE-EQUIVALENT CIR-
CUIT.
Y gain The gain (or gain control) of the vertical
channel of an oscilloscope or x-y recorder. Compare
X GAIN and Z GAIN.
yield In a phototube or photocell, the photoelectric
current per unit intensity of light.
yield map A diagram of an integrated circuit showing
the locations of faulty components.
yield strength The lowest stress for plastic deformation
of a material, below which the material is
elastic and above which it is viscous.
yield value The amount of physical stress that
causes a substance to become stretched permanently
out of shape.
YIG Abbreviation of yttrium-iron-garnet, a crystalline
material used in certain types of acoustic
delay lines, parametric amplifiers, and filters.
YIG crystal A crystal of yttrium-iron-garnet. See
YIG.
YIG filter A filter using a YIG crystal and tuned
electromagnetically.
YIG-tuned parametric amplifier A parametric
amplifier in which tuning is accomplished by continuously
varying direct current through the
solenoid of a YIG filter.
y intercept The y coordinate of the point at which
a line or plane intersects the y-axis.
ylem The material from which the primordial fireball
is thought to have been made, and from
which the entire known universe is believed to
have originated approximately 10 billion (10 10 )
years ago.
Y line A vertical line of a memory matrix. Compare
X LINE.
Y-matched-impedance antenna See WYE-
MATCHED-IMPEDANCE ANTENNA.
YMODEM In data transmission, an error-correcting
mode in which data is sent in blocks of one
megabyte (1MB), or 1,048,576 bytes. The source
and destination tally up the bytes in each block.
If they agree, the next data block is sent. If they
do not agree, the current data block is retransmitted.
Compare XMODEM and ZMODEM.
yoke 1. The ferromagnetic ring or cylinder that
holds the pole pieces of a dynamo-type generator
and acts as part of the magnetic circuit. 2. The
system of coils used for magnetic deflection of the
electron beam in cathode-ray tubes.
yoke method A method of measuring the permeability
of a sample of magnetic material. It involves
completing the magnetic circuit with a
heavy yoke of soft iron.
Young’s modulus Symbol, Y. The ratio of tensile
stress to tensile strain.
Y parameters The admittance parameters of a
four-terminal network or device.
Y point See WYE POINT.
Y position 1. On a cathode-ray screen, the vertical
position of the beam spot. 2. On a graph, the position
of a point along the vertical axis.
Y potential See WYE POTENTIAL.
yr Abbreviation of YEAR. Also, y.
Y rectifier See WYE RECTIFIER.
Y signal In color television, the monochromatic
signal conveying brightness information.
Y sink The circuit or device into which the Y lines
of a memory matrix feed. Compare X SINK.
ytterbium Symbol, Yb. A metallic element of the
rare-earth group. Atomic number, 70. Atomic
weight, 173.04.
ytterbium metals The rare-earth metals dysprosium,
erbium, lutetium, holmium, thulium, and
ytterbium.