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

Determine the b-h curves, Figure  shows the magnetic circuit of a relay. ...

Figure  shows the magnetic circuit of a relay. When each of the air gaps are 1.5mm wide find the mmf required to produce a flux density of 0.75 T in the air gaps. Use the B-

Is it is possible to have charge of 7.2*10^-19 c?, No;(Personal Note:Please...

No;(Personal Note:Please Rate this and let me know if this helps) Reason: From the quantisation of charge charactersistic, we can say that charge comes in integral multiple of e (

Determine the frequency of the supply, The voltage drops across two compone...

The voltage drops across two components when connected in series across an a.c. supply are v1 =150sin 314.2t and v2 =90sin(314.2t -∏/5) volts respectively. Determine (a) the v

Describe coefficient of self induction, Describe coefficient of self induct...

Describe coefficient of self induction, coefficient of mutual induction. What types of transformer is used in a bed lamp.

State kirchhoff rules of current distribution, State Kirchhoff's rules of c...

State Kirchhoff's rules of current distribution in an electrical network. Using these rules verify the value of the current in the electric circuit given below.

Work amd energy, newtons third law of motion

newtons third law of motion

current electricity, factors affecting emf of cel

factors affecting emf of cell

Special theory of relativity, Special Theory of Relativity deals with the ...

Special Theory of Relativity deals with the relativity of motion and of rest is called theory of relativity. In broad sense it divides into two parts (1)  GTR (General Theory o

Explain the energy, Explain the Energy Again, we have all heard about e...

Explain the Energy Again, we have all heard about energy. When the alarm clock rings in the morning we roll over and say, “I do not want to get up, I have no energy this mornin

Michelson interferometer, describe the construction and working of michelso...

describe the construction and working of michelson''s interferometer explain the formation of circular fringes how will you use these fringis in the determination of difference in

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