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

Dielectric, how dielectric mat is used for high voltage safety ? how it wor...

how dielectric mat is used for high voltage safety ? how it works?

Ultrasonics, explain briefly about piezoelectric effect to produce ultrason...

explain briefly about piezoelectric effect to produce ultrasonics

Explain radii of the two cross-sectional circular areas, Assume that two li...

Assume that two linked pistons are both cylindrical in shape. Show that the ratio of forces generated is directly proportional to the square of the radii of the two cross-sect

Construction and working of nicol prism, Briefly explain with principle, th...

Briefly explain with principle, the construction and working of Nicol prism. Why the angle of incidence on Nicol prism would be around 14 o .

First law of thermodynamics for a closed system, Illustrate the first law o...

Illustrate the first law of thermodynamics for a closed system undergoing cyclic process.

Evaluate frequency to shatter the glass, Evaluate frequency to shatter the ...

Evaluate frequency to shatter the glass with a resonant vibration? Standing-wave vibrations are set up in a crystal goblet with four nodes and four antinodes equally spaced arou

Determine the final velocity of football, An 82-kg receiver, moving 0.75 m/...

An 82-kg receiver, moving 0.75 m/s north, is tackled by a 110.0-kg defensive lineman moving 0.15 m/s east. The football players hit the ground together. Measure their final v

By which law the force acting between two point charges, The force acting b...

The force acting between two point charges can be computed using which of the following laws? a) Ohm's Law b) Ampere's Law c) Coulomb's Law d) Newton's Second L

Explain any one of the drawbacks of rutherford atom model, Q. Explain any o...

Q. Explain any one of the drawbacks of Rutherford atom model. As-per to the classical electromagnetic theory the accelerating electron must radiate energy at a frequency propo

To find current, Determine the unknown values in the following ta : ( s...

Determine the unknown values in the following ta : ( solve problems to find current, voltage, resistance  or power using ohm's law )

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