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

State the characteristics of antennas isolated, a. Explain the following te...

a. Explain the following terms in connection with electro-magnetic waves: (i) Transverse waves (ii) Power density (iii) Wave impedance (iv) Polarization b. State the chara

Electric and magnetic phenomena, The line density of charge in a wire is 0....

The line density of charge in a wire is 0.20 Cm-1. If this wire is symmetrically enclosed along its length by a cylindrical surface of radius 1.0 m and length 1.5 m, calculate

Collision centre of mass a d linear momentum, Ask question #Minimum 100 wor...

Ask question #Minimum 100 wora cannon of mass 5m ( including a shell of mass m )is at rest on a smooth horizontal ground fires the shell with its barrel at an angle A with the hori

Calculate the radius - protein with a density, 1.  A protein with a density...

1.  A protein with a density of 1.41 g/cm 3 has a molecular weight of 5000 g/mol. a. Calculate its radius. b. The radius measured during an experiment turned out to be 2.24

What is potential gradient, What is Potential Gradient Magnitude of ele...

What is Potential Gradient Magnitude of electric field at a point on an equipotential surface equal's rate of alter of potential, ΔV, with distance Δx, as point moves perpendic

Electrons are emitted from a photosensitive surface, Electrons are emitted ...

Electrons are emitted from a photosensitive surface when it is illuminated by green light but electron emission does not take place by yellow light. Will the electrons be emitted w

Gravitation- numerical probelm, A ball dropped from a balloon at rest clear...

A ball dropped from a balloon at rest clears a tower  81m high during the last quater second of its journey. Find the height of the balloon and the velocity of the body when it rea

Determine the velocity of the second ball, A cue ball has a mass of 0.160 k...

A cue ball has a mass of 0.160 kg is at rest on a frictionless pool table. The ball is hit dead center by a pool stick which applies an impulse of +1.40 Ns to the ball. He ball the

Define curie law, Curie law define the magnetic susceptibility of paramagne...

Curie law define the magnetic susceptibility of paramagnetic substances is inversely proportional to the absolute heat i.e.  Where C = Curie constant, T = absolute temperat

Hypothesis, short article...

short article...

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