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
Short
Circuit
It is a path in
electric circuit, whereby there is almost no resistance to the current in that
path.
SI
System of Units
The
currently used metric system of units is known as systeme international of
‘unite’s (International system of units) with international abbreviation SI.
The system is founded on base units for seven basic physical quantities. All
other quantities and units are derived from the seven base quantities and
units.
The
seven base quantities and their units are
|
Length ‘l’ --- Meter (m) |
Mass ’M’ --- Kilogram (Kg) |
|
Temperature (T) --- Kelvin (k); |
Luminous intensity -- Candela (cd) |
|
Time (t) --- second(s) |
Electric current (I) --- Ampere (A) |
|
Amount of Substance --- mole (mol) |
|
|
|
|
Siemens
It
is an alternative name for Mho. It is SI unit of electrical conductance and
equal to one ampere per volt.
Sievert
Unit of dose
equivalent when dose ‘D’ is measured in Grays
Signal-to-Noise
Ratio
Signal-to-Noise
ratio is one of the most widely used parameters to characterize detector
response. As the name suggests, it is given by the ratio of the signal to noise.
Silsbee
Effect
If the magnetic field produced by current
carrying super conductors exceeds critical value, the material loses
superconductivity and becomes normal. This phenomenon is called Silsbee effect
named after its discoverer.
Simple
Harmonic Motion
It is type of motion where the acceleration
is directed towards a fixed point (mean position of rest) and is proportional
to the displacement of vibrating particle.
Simple
Pendulum
An arrangement of a heavy particle suspended by means of a weightless
inextensible, flexible string from a rigid support making simple harmonic
oscillation about mean position.
Simulator
Sin(angle of incidence)/Sin(angle of
refraction) = refractive index (medium).
Single
Crystal
A crystal in which there is periodic
arrangement and repeated arrangement of atoms exists throughout the crystal
without any disturbance. All unit cells interlock in same fashion and have same
orientation.
Sintering
Particle
coalescence of a powdered aggregate by diffusion that is accomplished by fixing
at an elevated temperature is called as sintering.
Sinusoidal
Function
Function having
mathematical form given by Asin(2pft); where ‘A’ is the amplitude
of the wave, ‘f’ is its frequency and ‘t’ is time.
Sinusoidal
Oscillator
Electronic device which produces sine waves.
Sinusoidal
or Sine Wave
A sine wave is a
repetitive change or motion which, when plotted as a graph, has the same shape
as the sine function.
Siren
A device in which
compressed air or steam is driven against a rotating perforated disk to create
a loud sound as a signal or warning.
Skin
Depth
The
depth inside the conductor at which the amplitude of electromagnetic decreases
by a factor 1/e. It is measure of depth to which an Electromagnetic wave
penetrates.
Skin Effect
When
an alternating current of high frequency flows through the conductor, current
density is not uniform throughout the crossectional area. Current density is
more near the surface than inside the conductor. High frequency alternating
current is confined to surface layer. The phenomenon is called as “skin
effect”.
Slip
Plastic deformation as the result of
dislocation motion, also the shear displacement of two adjacent planes of
atoms.
Smoke
Smoke is a collection of a airborne
solid and liquid particulates and gases emitted when a material
undergoes combustion
together with the quantity of air that is entrained or otherwise mixed into the mass. It
is commonly an unwanted by-product of
fires.
Snell’s
Law
An empirical
relationship formulated by Willeboard Snell around 1621, which is used to
describe the relationship between the angles of incidence and refraction,
when referring to light or other waves passing through a boundary between
two different isotropic media. Snell's law states that the ratio of
the sine of the angles of incidence and refraction is equivalent to the
ratio of phase velocities in the two media, or equivalent to the
reciprocal of the ratio of the indices of refraction.
Solar
Day
A solar day is
the time it takes for the Earth to rotate about its axis so that the sun appears
in the same position in the sky.
Solar
Eclipse
As seen from
the Earth, a solar eclipse is a natural phenomenon which occurs
when the Moon passes between the Sun and Earth, and the
Moon fully or partially blocks ("occults") the Sun.
Soft
Magnetic Material
A ferromagnetic
or ferrimagnetic material having small B vs H hysteresis loop, which may be
magnetized and demagnetized with relative ease.
Soft
Radiation
Term usually
attributed to X-ray radiation or other particles or photons having very low
energy, and, as a result, do not penetrate any type of material easily.
Softening
Point (Glass)
The maximum
temperature at which a glass piece may be handled without permanent
deformation; this corresponds to a viscosity of approximately 4x106
Pa.Sec
Solar
Cell
A solar cell is a PN junction in which
generation of carriers by an external source of energy, usually sunlight is
utilized to generate electrical power. Solar cell operation is based on
generation of electron – hole pairs in transition region, and the separation of
both types of carriers by the junction electric field.
Solar
Constant
It is the amount of radiant energy received
from the sun by the earth per unit area per unit time normally at the mean
distance of earth from the sun. The numerical value is 1.388 x 103
Wm2.
Solar
Day
Time taken by the
moon to complete one rotation around the earth.
Solar
Wind
The corona, the sun's outer layer, reaches temperatures of up to 2 million degrees Fahrenheit (1.1 million Celsius). At this level, the sun's gravity can't hold on to the rapidly moving particles, and it streams away from the star. The solar wind is a stream of energized, charged particles, primarily electrons and protons, flowing outward from the Sun, through the solar system at speeds as high as 900 km/s and at a temperature of 1 million degrees (Celsius). It is made of plasma.
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