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
Bosons
A group of elementary particles named after well known physicist Satyendranath Bose. They are of two types i) Mass less Bosons created by fields; Photons & Gravitons fall under this category ii) Bosons which are formed in strong interactions; Pions & Kaons fall under this category.
Boundary
Anything which
separates system and surroundings is called boundary (envelope or wall). The
envelope may be imaginary or real; it may be rigid or non-rigid; it may be a
conductor of heat (diathermic wall) or a non-conductor of heat (adiabatic
wall).
Boyle’s
Law
Law as per which
at constant temperature, the volume of a given mass of a gas is inversely
proportional to its pressure.
Brackett
Series
It is the
spectrum of wavelengths falling in Infrared region formed due to electron
transitions from higher energy states to fourth orbit.
Bragg
Curve
It is plot
between residual energy of charged particle passing through matter vs stopping
power. Variation of stopping power with respect to residual energy is called as
Bragg curve. By residual energy, we mean the instantaneous energy of the
particle retained by it as it travels through the material.
Bragg’s
Law
Bragg’s law was
introduced by Sir W H Bragg and his son Sir W L Bragg. The law states that when X-rays
are incident on crystal lattice with angle of incidence equal to angle of
scattering; peaks of scattered intensity are observed (constructive
interference) when difference in path length is an integral number of
wavelength.
Branching
Ratio
Branching ratio
is a term that is used to characterize the probability of decay through a mode
with respect to all other modes. For instance if a nuclide decays through α and γ modes with branching ratios of 0.8 and 0.2, it would imply that α-particle
is emitted in 80% of decays while photons are emitted in 20% of decays.
Brass
A copper rich
copper zinc alloy. Alloy consists of Copper and Zinc in variable
proportions.
Brazing
American welding
society defines it as metal coalescence above 800oF. Brazing
involves bonding of two surfaces by using molten filler material along with
flux to eat through oxide layer.
Breakdown
Voltage
It is the minimum
voltage which when applied to an insulator loses its insulating property and
becomes highly electrically conductive.
Breeder
Reactor
Type of nuclear
reactor capable of producing fissionable material simultaneously at the expense
of burning of fissile material, is called as Breeder reactor. Upon neutron
absorption by U-238, it gets converted to Pu-239 which is fissile. The coolant
used is liquid metal, usually Sodium as it acts as good heat transfer medium
without slowing down of neutrons which is essential for breeding ratio. The
reactor core uses high enriched U-235 initiate production of fast neutrons. The
core is surrounded by blanket of U-238. Upon neutron absorption by U-238, it
gets converted to Pu-239 which is fissile. This makes the chain reaction to
sustain for longer periods.
Breeding
Nuclear process
used in breeder reactor as per which non fissionable isotopes yield fissionable
isotopes upon capture of fast neutrons.
Bremsstrahlung
X-rays
The Bremsstrahlung
radiation incident on a suitable target, knock out electrons leading to X-rays
from target material called as Bremstrahlung X-rays.
Bremstrahlung
It is a German
word which means braking radiation. Radiation emitted in the form of photons
when an energetic electron gets decelerated in the field of atomic nucleus in
the matter. Generally speaking, if a
charged particle has energy much greater than its rest energy emits
Bremsstrahlung radiation if it encounters resistance while moving through a
medium.
Brewster’s
Angle of Incidence
It
is the angle of incidence of electromagnetic wave at an interface which yields
reflected beam which is totally polarized parallel to the interface and a
transmitted beam that is partially polarized perpendicular to it.
or
It
is the angle at which incident electromagnetic wave crosses interface between
two medium without suffering reflection.
Brewster’s
Law
According to this
law, the light reflected from a surface is completely polarized if the
reflected beam and the beam refracted into material form a right angle. If the
incident beam is polarized in plane of incidence there will be no reflection at
all. Only if incident beam is polarized normal to plane of incidence, it will get
reflected.
Brillouin
Zones
Electrons moving in a periodic potential lattice can have energy values only between allowed regions or zones called as Brillouin zones.
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