A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
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Ordinate
The Cartesian coordinate obtained by measuring parallel to the y-axis.
Origin
The point of intersection of coordinate axes as in Cartesian coordinate system
Orthogonal
Having a set of mutually perpendicular axes, meeting at right angles having perpendicular slopes or tangents at the point of intersection.
Oscillation
Type of motion in which object moves about a mean position i.e. fixed point.
Oscillator (Electric)
Electronic circuit which converts the dc power supply voltage to an output waveform of some frequency. The oscillator circuit is used to generate various waveforms.
Osmosis
Diffusion of fluid through a semi permeable membrane from a solution with a low solute concentration to a solution with a higher solute concentration until there is an equal concentration of fluid on both sides of the membrane.
(or)
A process of diffusion of a solvent (such as water) through semi- permeable membrane, which will transmit the solvent but impede most dissolved substances. The normal flow of solvent is from the dilute solution to the concentrated solution.
Ostwald’s Second Law of Thermodynamics
“Perpetual machine of second kind is impossible”.
Outgassing
Constant
Rate at which gas
appears to emanate from unit area of surface, and is usually measured in units
of Torr.liter.sec-1.cm-2.
Outgassing
The emanation of gases from surface of
material resulting from desorption.
Oxidation
The removal of one or more electrons from
an atom, ion or molecule.
Ozone
Ozone is an allotrope of oxygen containing
three oxygen atoms. The chemical formula for ozone is O3. Ozone,
the first allotrope of
any chemical element to
be recognized, was proposed as a distinct chemical substance by Christian Friedrich Schönbein in 1840, who named it after the Greek verb ozein ("to smell"),
from the peculiar odor in lightning storms. According
to experimental evidence from microwave spectroscopy, Ozone is a bent molecule, with C2v symmetry (similar to the water molecule).
Ozone
Layer Depletion
The ozone layer is located between 10 and
50 km above the Earth's surface and contains 90% of all stratospheric ozone. Under
normal conditions, stratospheric Ozone is formed by a photochemical reaction
between oxygen molecules, oxygen atoms and solar radiation. The ozone
layer is essential to life on earth, as it absorbs harmful ultraviolet-B
radiation from the sun. In recent years the thickness of this layer has been
decreasing, leading in extreme cases to holes in the layer. Measurements
carried out in the Antarctic have shown that at certain times, more than 95% of
the ozone concentrations found at altitudes of between 15 and 20 km and more
than 50% of total ozone are destroyed, with reductions being most pronounced
during winter and in early spring. Natural phenomena, such as sun-spots and
stratospheric winds, also decrease stratospheric ozone levels, but typically
not by more than 1-2%. The main cause of ozone layer depletion is the
increased stratospheric concentration of chlorine from industrially produced Chloro
Fluoro Carbons, Halons and selected solvents.
