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
Hadrons
Kaons, Pions
together with Baryons are placed in group of strongly interacting particles
called Hadrons.
Half
Life
Term used in
nuclear physics. It represents the time it takes for a radioactive isotope for
decaying its activity to half of its present value.
Half
Wave Plate
Plate of uniaxial double refracting
crystals such as quartz and calcite with optic axis parallel to their
refracting surface, the thickness of which is such that it produces a path
difference of λ/2 or a phase difference Π in between ordinary and extra ordinary
waves.
Half-Wave
Rectifier
Device which conducts
current only during the positive half cycles of input ac supply. The negative
half cycles of ac supply are suppressed i.e. during negative half cycles, no
current is conducted and hence no voltage appears across load. Therefore,
current always flows in one direction (DC) through load after every half
cycle.
Hall
Effect
When a piece of
semiconductor carrying a current is placed in a transverse magnetic field, an
electric field is produced inside the conductor in a direction normal to both
current and magnetic field.
Hall
Mobility
Mobility of
charge carriers under Hall Effect defined as product of hall coefficient and
conductivity.
Hall
Probe
Hall probe is a
magnetic field sensor that passes electric current when the sensor is
perpendicular to magnetic field. The stranger the magnetic field the more the
current is converted to voltage. They are used for proximity switching,
positioning etc.
Hamilton’s
Principle
If a particle
moves from one point to other in time interval t1 ≤ t ≤ t2, then the actual path it follows is the one for
which action assume stationary value.
Hamiltonian
Principle
The path actually
traversed by a conservative, holonomic dynamical system from time t1 to
t2 is one over which the integral of the lagrangian between limits t1
and t2 is stationary i.e., the time integral of lagrangian is
extremum.
Hard
Radiation
The term
attributed to high energetic X-rays or gamma rays having high penetration power
into almost all materials.
Hardness
Mechanical
property which is a measure of materials resistance to localized plastic
deformation.
Harmonic
Motion
See simple harmonic motion.
Health
Physics
It is branch of
physics which deals with radiation protection of occupational workers in
nuclear reactors and other radiation material handling centers.
Heat
Capacity
The quantity of
heat required to raise the temperature of the whole body there 1oC
or 1oK is called heat capacity of body.
Heat
Engine Law
Conversion of
total heat energy into work is impossible.
Heat
Engine
It is cyclic
process in which heat is continuously converted into mechanical work. It has 3
main parts: source, sink and working substance. i) Source of heat at constant
temperature to drive heat; ii) Sink at constant temperature, heat can be
supplied without change in temperature. iii) Working substance: absorbs heat
from source, converts part of the heat into mechanical work & rejects
remaining heat to sink.
Heat
It
is a form of energy (kinetic energy of molecules constituting the body) which
produces sensation of warmth.
(or)
It
is energy that is transferred between a system and its environment because of a
temperature difference that exists between them.
Heavy
Water
Also referred as
Deuterium oxide, is a type of water in which Deuterium (an isotope of Hydrogen)
substitutes Hydrogen i.e. D2O. It has importance for having
properties like Neutron moderation, high boiling point etc.
Heisenberg
Forces
Type of nuclear
force in which there is exchange of both spin and position coordinates.
Heisenberg’s
Uncertainty Principle
Based on wave
nature of matter, Heisenberg proposed a principle according to which,
macroscopically it is possible to exactly measure position of moving particle
and momentum associated with it but microscopically it is not possible.
According to this principle, product of uncertainties in the measurement of
position and momentum is of order of h/2π; where ‘h’ is Planck’s constant.
Helicity
Lee and yang suggested that the violation
of parity in beta decay was direct consequence of longitudinal polarization of
emitted electrons and Neutrons. The state and degree of longitudinal
polarization of particles is represented by the term Helicity.
Heliocentric Theory
The theory proposed by Nicolas Copernicus, a polish astronomer. Heliocentric system first appeared in his book “De revolutionibus orbium coelestium”, “on the revolutions of heavenly bodies” which appeared in 1543. “Helios” in Greek means “sun”. Heliocentric means that the sun is at the center. As per this theory, sun remains at center and all the planets revolve round it. The moon is only celestial sphere in the system that revolves round the earth and together around sun.
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