User Account

All Pages

Population inversion, Physics

Assignment Help:
population inversion
  • The process in which the number of electrons (N2) in a higher energy state called ‘metastable state of an active medium is increased to a value greater than the number of electrons (N1) in the ground state (i.e.N2 > N1) is called population inversion.
  • There are certain special substances or systems in which the electrons, once excited can remain in the higher energy state for longer times.
  • Such systems are called Active systems or Active Media.
  • Active systems are generally compounds or mixtures of different elements.
  • Consider three electronic states 1,2,3, in an active medium. (Refer text book for diagram.
  • Normally Large number of electrons exist in the Lowest energy state called ground state.
  • Let this number be N1 when photons of energy equal to the difference between E3 and E1 are incident, the electrons from state (1) are excited to state (3) because of absorption. But the property of the state (3) is such that the life time of electrons
  • in the state is very short, of the order 10-8 seconds. 
  • Of course most electrons return to state (1) from state (3) by spontaneous emission, but some electrons go to state (2) also.
  • Therefore, the electrons from the state (3) undergo a quick transition to the state (2) by emitting only a small energy (E3 - E2) which is simply absorbed as the thermal energy by the medium itself.

Related Discussions:- Population inversion

Evaluate with the magnitude of the force exerted on particle, Questions: ...

Questions: Regard as two charged particles at a separation of 4 cm. Particle #1 has a charge of +2 micro-coulombs. Particle #2 has a charge of +16 micro-coulombs. How does the

Gravitety, why fall an apple from a tree

why fall an apple from a tree

Radioactivity, A radioactive substance has a half life of 1 min. If one nuc...

A radioactive substance has a half life of 1 min. If one nuclei decays now , when will be next decay????

Rectilinear motion, Elevator Problem

Elevator Problem

Dimensional analysis, can you please give me a step wise answer for finding...

can you please give me a step wise answer for finding the dimension of impulse

Seebeck effect, a) Here temperature difference of junction is used to produ...

a) Here temperature difference of junction is used to produce thermo e.m.f. and vice-versa. b) This effect produced when junctions of a thermocouple are kept at dissimilar tempe

Explain the principle and working of a light emitting diode, Define, with t...

Define, with the help of a schematic diagram, the principle and working of a Light Emitting Diode. What criterion is kept in mind whereas choosing the semiconductor material for su

Ac equivalence circuit with active devices, notes on ac equivalence circuit...

notes on ac equivalence circuit with active devices

Determine the current taken by the capacitor, A motor has an output of 4.8k...

A motor has an output of 4.8kW, an efficiency of 80% and a power factor of 0.625 lagging when operated from a 240V, 50Hz supply. It is needed to improve the power factor to 0.9

Define core type transformers, Core type Transformers: In this type of ...

Core type Transformers: In this type of transformer the windings enclose the core (fig. given below). Both the windings are divided and half of every winding is placed on eac

Write Your Message!

Captcha
Order Assignment

Featured Services

Order Now

Popular Subjects

Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

Submit Assignment

Academics

Major Subjects

Majors

Get In Touch

whatsapp: +91-977-207-8620

Phone: +91-977-207-8620

Email: [email protected]

TERMS & POLICIES

HELP & SUPPORT

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd