Showing posts with label ensemble. Show all posts
Showing posts with label ensemble. Show all posts

PHYSICS DICTIONARY

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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.