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
Thermal
Expansion
Expansion of
liquid, solid or gas due to subjection of temperature.
Thermal
Neutron
Neutrons
whose average kinetic energy is reduced to that of atoms of medium in which
they are travelling at a particular temperature are called thermal neutrons.
or
When
a Neutron moving in a medium attains thermal energy of atoms of medium at ambient
temperature, then it is said to be thermal neutron.
Thermal
Radiation (Thermodynamics)
It is the
mechanism of heat transfer through electromagnetic waves. This type of heat
transfer can take place even through vacuum.
Thermal
Runaway
The self destruction
of an unstabilised transistor is known as thermal runaway.
Thermal
Shock:
The fracture of a
brittle material as a result of stresses that are introduced by a rapid
temperature change is called as thermal shock.
Thermal
Stress
Residual stress
introduced within a body resulting from change in temperature.
Thermalization
of Neutrons
Slowing down of
neutrons having high energy to energies below 1eV is called thermalization of
neutrons.
Thermionic
Emission
It is defined as emission of charge
carriers from surface of a solid or over some kind of potential barrier facilitated
by supplying thermal energy to the solid. Charge carriers so released from
solid are called thermions and science dealing with this phenomenon is called Thermionics.
Thermionic
emission is controlled by 3 characteristics of emitter:
a)
Its temperature b) Its material composition (work function) and
c)
Its surface area.
Thermocouple
It is a sensor used for measuring temperature.
It consists of two dissimilar metals, joined together at one end. When the
junction of two metals is heated or cooled, a voltage is produced that can be
correlated back to the temperature.
Thermodynamic
Potentials
Energy
functions which depend on variables P, V, T and S to completely describe
thermodynamic system are called thermodynamic potentials. Four main
thermodynamic potentials are Internal energy, Helmholtz energy, Enthalpy &
Gibbs free energy.
Thermodynamic
Scale of Temperature
It is that scale which doesn’t depend on the
nature of its working substance or its thermometric property.
Thermodynamics
IIIrd Law
The heat
capacities of all solids tends to zero as the absolute zero of temperature is
approached and that the internal energies & entropies of all substances
become equal there, approaching their common value asymptotically.
Thermodynamics
IInd Law
Every chemical or physical or natural
process in nature takes place in such a manner that total energy increases or
remains constant.
Thermodynamics
Ist Law
When a definite amount of work is done a certain
amount of heat is produced & vice versa.
Thermodynamics
It is experimental
or empirical science which deals with macroscopic properties of matter.
Thermometer
Device used to measure temperature.
Thermoplastic
Materials which
soften when heated (and eventually liquefy) and harden when cooled, process
that is totally reversible and may be repeated.
Thermos
flask
See deewar flask.
Thermostat
Device used to maintain steady temperature.
It consists of bimetallic strip used to control the connection.
Thevenin’s
Theorem
In a linear network consisting of emf’s and
resistances connected between two points ‘A’ and ‘B’ is equivalent to a single
effective emf in series with an effective resistance connected between ‘A’ and ‘B’.
Thin
Film
Films having thickness between 100 Ao
to 10000 Ao.
Thompson
Scattering
Elastic scattering process between a free
electron and a photon of low energy.
Thomson
Model of Atom
In 1898, Joseph J. Thomson proposed an atomic model in which mass of atom is distributed uniformly over the volume of atom with a radius of order 1Ao and negatively charged electrons are dispersed uniformly with in a continuous spherical distribution of positive charge. The electrons forms rings and each ring can accommodate a certain upper limit in the number of electrons and then other rings begin to form. With this ring structure Thomson could in principle account for periodicity of properties of elements. Thomson’s atomic model is often referred as “Plum Pudding model “.
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