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 velocity of a wave frequency, The frequency of a wave is 50 H...

The frequency of a wave is 50 Hertz and its wavelength is 25 meters. What is the velocity of this wave? Ans: The velocity of given wave is 1250 meters/second.

CT Physics, Photon flux

Photon flux

Electrostatic, what is electric field

what is electric field

Find the electric flux, The elctric field in a certain region of space has ...

The elctric field in a certain region of space has components E x = 6.0 N/C, E y = 7.0 N/C, and E z = 0. Find the electric flux though the surface x = 6 y , 0 x

Physics chapter 2-Motion in One Dimension, An express train, traveling at 3...

An express train, traveling at 36.0 m/s, is accidently sidetracked onto a local train track. The express engineer spots a local train exactly 100 m ahead of the same track and trav

Magnetic effect of the earth, Magnetic effect of the earth is? Magnetic...

Magnetic effect of the earth is? Magnetic effect of the earth. The earth behaves as it has got a big magnet, running as mot a big magnet, running almost from its north to South

Explain avalanche breakdown, At high reverse voltage, due to high electric ...

At high reverse voltage, due to high electric field, the minorities charge carriers, while crossing the junction acquires very high velocities. A chain reaction is prepared, giving

Describe dispersive power of a medium for a pair of colours, What do you me...

What do you mean by lateral shift produced by a parallel sided glass slab for grazing incidence of light? Describe dispersive power of a medium for a pair of colours.

How far will a force stretch the spring, A certain spring is known to obey ...

A certain spring is known to obey Hooke's Law.  If a force of 10 newtons stretches the spring 2 meters, how far will a 30 newton force stretch the spring? Ans: A certain spr

Explain semi conductors, Semi conductors: Semi conductors are these sub...

Semi conductors: Semi conductors are these substances which lie among conductor and insulators. Semi conductor is those substances which hardly pass electric current by them

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