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

Isolated magnetic poles, Isolated magnetic poles do not exist'. explain? ...

Isolated magnetic poles do not exist'. explain? A. 1. If a bar magnet is cut into smaller and smaller pieces eventually ending with the smallest possible piece, this smallest

Vibration magnetometer experiment, what is procedure of vibration magnetome...

what is procedure of vibration magnetometer

How many bullets can he fire per second at the most?, A machine gun fires a...

A machine gun fires a bullet of mass 40 g with a velocity 1200 m/s  The man holding it, can exert .  a maximum force of 144 N on the gun. How many bullets can he fire per second at

Examples, Example of like and unlike parallel forces

Example of like and unlike parallel forces

Which one of the subsequent is true of electric potential, Question: W...

Question: Which one of the subsequent is true of electric potential but isn't true of an electric field? Answer: The electric field acquaintances a vector with empt

Wavelength of the wave , A standing wave is described by the wave function ...

A standing wave is described by the wave function  where x and y are in meters and t is in seconds. (a) Prepare graphs showing y as a function of x for five instants: t = 0, 5 ms,

Thin films, .In order to deposit films of the alloy YBa2Cu3, the metals Y, ...

.In order to deposit films of the alloy YBa2Cu3, the metals Y, Ba, and Cu are evaporated from three point sources. The latter are situated at the corners of an equilateral triangle

Projectile motion, If a ball thrown horizontally with a velocity of 20m/s f...

If a ball thrown horizontally with a velocity of 20m/s from a tower meters high, after how long will it strike the ground?

Radiation, what is radiation

what is radiation

Explain stator, STATOR:   It is made up of a number of stampings which are ...

STATOR:   It is made up of a number of stampings which are slotted to be given windings. The stator carries 3φ windings and is fed from 3φ supply. It will be for a exact number of

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