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
Spectrum
It is colored pattern obtained on screen
after dispersion of light.
Speed
Distance per unit
time.
Speed
of Light
It is denoted by
‘C’ and its value in vacuum is 2.99792458 x 108 m/sec.
Sphere
of Influence
A sphere drawn with a molecule as centre
and molecular range as radius is called sphere of influence.
Spherical
Aberration
Spherical mirrors
have an aberration. There is an intrinsic defect with any mirror that takes on
the shape of a sphere. This defect prohibits the mirror from focusing the
entire incident light from the same location on an object to a precise point.
The defect is most noticeable for light rays striking the outer edges of the
mirror. Rays that strike the outer edges of the mirror fail to focus in the
same precise location as light rays that strike the inner portions of the
mirror. While light rays originating at the same location on an object reflect
off the mirror and focus to a point, any light rays striking the edges of the
mirror fail to focus at that same point. The result is that the images of
objects as seen in spherical mirrors are often blurry.
Spin
It is a quantum mechanical phenomenon
attributed to elementary particles, which is intrinsic form of angular
momentum. All elementary particles of a given kind have the same magnitude of
spin angular momentum, which is indicated by assigning the particle
a spin quantum number.
However, in a technical sense, spins are not strictly vectors and they are
instead described as a related quantity: a Spinor.
Spin
Magnetic Moment
Magnetic moment
associated with spinning electron.
Spinor
Spinors were discovered by Élie Cartan in 1913. Later, spinors were adopted
by quantum mechanics in order to study the properties of the intrinsic angular momentum of the electron and
other fermions. In mathematics and physics, in
particular in the theory of the orthogonal groups (such as the rotation or
the Lorentz groups), Spinors are
elements of a complex vector space introduced
to expand the notion of spatial vector.
Unlike tensors, the
space of Spinors cannot be built up in a unique and natural way from spatial
vectors. However, Spinors transform well under the infinitesimal orthogonal
transformations (like infinitesimal rotations or
infinitesimal Lorentz transformations). Under the full orthogonal group,
however, they do not quite transform well, but only "up to a sign".
This means that a 360 degree rotation transforms a Spinor into its negative,
and so it takes a rotation of 720 degrees for a Spinor to be transformed into
itself. Specifically, Spinors are objects associated to a vector space with a quadratic form (like Euclidean space with
the standard metric or Minkowski space with
the Lorentz metric),
and are realized as elements of representation spaces of Clifford algebras.
Spin
Quantum Number
It is one of the
four quantum numbers associated with energy levels of electrons in an atom. It
has either +1/2 or -1/2 value.
Spin-Orbit
Coupling
See L-S coupling
Spontaneous
Fission
Spontaneous fission is a form of
radioactive decay where an atom's nucleus splits into two smaller nuclei and
generally one or more neutrons, without any external interference.
Spontaneous
Emission
An atom in an
excited state can decay down to a lower state by emitting a photon with energy
equal to the difference between the initial higher energy level and the final
lower energy level. When this process takes place naturally, rather than being
initiated by disturbing the atom somehow, it is called spontaneous emission.
Sputtering
The process in
which a surface is bombarded with energetic particle to cause ejection of
surface atoms. The technique is used to make thin films on a substrate.
Square
Wave
A square wave is
a type of periodic waveform where the signal has only two levels. The signal
switches between these levels at regular intervals and the switching is instantaneous.
These qualities mean a graph of the wave over time will produce shapes with
square corners. The square wave has practical uses in digital circuits.
Stabilized
Transistor
The process of
making operating point independent of temperature changes or variations in
transistor parameters is known as stabilization.
Standard
Deviation
The
standard deviation is the square root of the variance.
or
The square root of arithmetic mean of the squares of deviation is called as standard deviation.
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