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
Electrostatics
Branch of physics
which deals with charges permanently fixed in space or in steady flow in a
circuit.
Electrostriction
It is phenomenon
of elastic deformation of dielectrics in an electric field. Electrostrictive
strain is proportional to square of electric field strength and is independent
of reversal of direction of electric field. Electrostriction is caused by die
electric polarization in an electric field and occurs in all dielectrics,
whether solid, liquid or gaseous. In solid dielectrics, electrostriction is
very small and is of no practical importance.
Element
Substance
consisting of only one type of atoms that have same atomic number.
Elementary
Charge
Electric
charge carried by a single proton or electron. It is fundamental physical
constant. This charge has a measured value of approximately
1.602176565x10-19
coulombs. In CGS, system it is 4.80320425x10-10 stat coulomb.
Elementary
Particle
Particles which
are considered as not having sub structure i.e. irreducible constituent of
matter.
Elliptically
Polarized Light
Due to the
superposition of two plane polarized light waves with a definite phase
difference, the resultant light vector revolves with a varying amplitude
periodically in a plane perpendicular to direction of propagation of light and the
tip of light vector describes an ellipse. Light is called elliptically
polarized light.
EMF
It is the influence which maintains permanent
potential difference between the terminals of source, ensuring continuous
supply of current. EMF is electrical energy of non electro static origin.
Emissivity
The ability of a
surface to emit radiant energy compared to that of a black body at the same
temperature and with same area. It is defined as the total amount of radiant
energy emitted per second per unit area by a surface is called total emissivity
of that surface.
Emission
Spectrum
It is of 3 types i)
Continuous spectrum ii) line spectrum &
iii) Band spectrum
Empirical
Scientific
information acquired by means of experience or observation or experimentation
without using scientific method or theory.
Electromagnetic
Unit (emu)
Any unit that belongs to system of CGS
units for electricity and magnetism based on system of equations in which
permeability of free space is taken as unity.
Endoergic
See Endothermic reaction.
Endothermic
Process
Chemical
reactions for which energy absorption is must. They cannot occur spontaneously.
Work must be done in order to get these reactions to occur. When endothermic
reactions absorb energy, a temperature drop is measured during the reaction.
Endothermic reactions are characterized by positive heat flow and an increase
in enthalpy.
Energy
Band
In solids, when
atoms come within close proximity of one another, electrons are acted upon, or
perturbed, by the electrons and nuclei of adjacent atoms. This influence is
such that each distinct atomic state may split into a series of closely spaced
electron states in the solid, to form what is termed electron energy band. The extent
of splitting depends on inter atomic separation and begins with outermost
electron shells since they are first to be perturbed as atoms coalesce. Within
each band, energy states are discrete.
Energy
Density
It is the amount
of energy stored in a given system or region of space per unit volume or mass.
Energy
Level
Quantized states
for particles in atom or nuclei.
Energy
Minimum Principle
For an isolated
system in state of equilibrium, energy reaches a minimum value and after that
remains constant.
Energy
of Dissociation
It is the energy
required to dissociate two atoms of molecule in to an infinite separation.
Energy
It is ability to
do work. Energy is an attribute of a physical object or of whatever is
contained in a specific region of space.
Enrichment
A process of
isotopic separation by which relative abundance of isotopes of a given element
is altered, thus producing a form of element that has been enriched in one or
more isotopes and depleted in others.
Ensemble
An ensemble is defined as a collection of large number of microscopically identical but essentially independent systems.
