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

Explain the energy and power in circuits, Explain the Energy and Power in C...

Explain the Energy and Power in Circuits Electrical power dissipated in a circuit or a single circuit element can be calculated using P = I V     where power (P) is in wa

Pseudo force, define pseudo force and mathematical expression and explanati...

define pseudo force and mathematical expression and explanation

Permeability of free space, Permeability of free space; magnetic constant; ...

Permeability of free space; magnetic constant; mu_0 The ratio of the magnetic flux density in a substance is to the external field strength for vacuum. This is equal to 4 pi x

Explain about the term electron microscope, Explain about the term electron...

Explain about the term electron microscope. Electron microscope: An electron microscope is a form of microscope which uses electrons to illuminate a specimen and make an enl

Steradian, steradian; sr: The supplementary SI unit of solid angle des...

steradian; sr: The supplementary SI unit of solid angle described as the solid central angle of a sphere which encloses a surface onto the sphere equivalent to the square of t

., 100 =6=4=9=7=9

100 =6=4=9=7=9

State ohms law, Q State Ohm's law. At a steady temperature that the st...

Q State Ohm's law. At a steady temperature that the steady current flowing through a conductor is directly proportional to the potential difference between the two ends of the

Forces, what is the difference between pulling and pushing forces

what is the difference between pulling and pushing forces

Displacement, How do you calculate the initial velocity?

How do you calculate the initial velocity?

What is the resistance of a coil of aluminium wire, What is the resistance ...

What is the resistance of a coil of aluminium wire The resistance of a coil of aluminium wire at 18 ? C is 200?. The temperature of the wire is increased and the resistance

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