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
Big
Bang Theory
The Big Bang
theory is an effort to explain what happened at the very beginning of our
universe. According to
the theory, our universe sprang into existence as "singularity"
around 13.7 billion years ago. Our universe is thought to have begun as an
infinitesimally small, infinitely hot, infinitely dense, something called as
singularity. The Big Bang theory is the scientific theory that is most consistent with observations of the past and present
states of the universe, and it is widely accepted within the scientific community. Georges LemaƮtre first proposed the
Big Bang theory which he called as "hypothesis of the primeval atom".
The framework for the Big Bang model relies on Albert Einstein's
general relativity and on simplifying assumptions such
as homogeneity and isotropy of
space.
Bimetallic
Strip
Two different
metal strips of equal lengths placed on each other is called bimetallic strip.
On heating, bimetal bends with material of greater linear expansion to convex
side. On cooling, it bends with material of greater linear expansion on concave
side.
Binary
System
The pair of stars
which orbit around each other is referred to as binary system. The center of
mass of the binary system lies in between the two stars. The two stars rotate
about this point.
Binding
Energy per Nucleon
See average
binding energy.
Binding
Energy
The energy
equivalent of mass defect is called binding energy. It is this energy which
binds nucleons together. Hence it is the energy required for breaking a nucleus
into free neutrons and protons.
Binoculars
Binoculars are a
parallel combination of two telescopes for viewing an erect 3 dimensional image
with both eyes. The image of same size can be viewed with both eyes which is uncomfortable
for users to see with single eye. The distance between telescopes is
adjustable.
Bioluminescence
It is the phenomenon
of emission of light by living creatures because of chemical reaction.
Biophysics
Biophysics is an interdisciplinary science that
deals with the application of physics to biological processes and phenomena.
Biot
& Savart law
This law gives relation
between magnetic field due to current carrying conductor and current flowing in
the element. dB at a distance ‘r’ from a current element ‘dL’ carrying a
current I is found to be proportional to I , to the length dL and inversely to
the square of the distance r. The direction of magnetic field is perpendicular
to line element dL as well as radius r.
Biprism
A triangular
prism with vertex angle of nearly 180o used to obtain images of a
single source in observing the interference light.
Birefringence
Some crystals
have property of splitting incident light ray into two refracted rays. It is
due to optical anisotropy in the binding forces between the atoms forming a
crystal. They have two indices of refraction. This property is called
birefringence.
Black
Body
A
body which completely absorbs radiation of all wavelengths incident on its
surface and doesn’t reflect any part of it is called as black body.
(or)
It is a body which emits thermal radiations of all wavelengths when heated to high temperature.
Black
Hole
A black hole is a region of space-time of extreme density
with such strong gravitational attraction due to which nothing can escape, even
light. When a star burns through the last of its fuel, it may find itself
collapsing. For smaller stars, up to about three times the sun's mass, the new
core will be a neutron star or a white dwarf. But when a larger star collapses,
it continues to fall in on itself to create a stellar black hole.
Bloch
Theorem
It is a mathematical theorem which gives us the form of
electron wave function in a periodic potential. As per this theorem, electron
in a one dimensional lattice behaves as plane wave.
Blue
Moon
When two full moons occur in a single
month, the second full moon is called a "Blue Moon".
