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

Basic elactronics, recombination of electrons and holes impurity semiconduc...

recombination of electrons and holes impurity semiconductor

Projectile motion, after 1sec of projectile makes an angle of 45 with the h...

after 1sec of projectile makes an angle of 45 with the horizontal after another 1 sec travelling horizontally find magnitude of initial velocity and angle of projection

Determine the evaporation rate, An industrial process involves the evaporat...

An industrial process involves the evaporation of water from a liquid film that forms on a contoured surface. Dry air is passed over the surface, and from laboratory measurements t

How to improve power factor, Step to improve Power Factor By using stat...

Step to improve Power Factor By using static capacitor: Static capacitor is usually used to better the power factor of the power system. As the capacitor draws leading curre

What is the magnitude of the northward acceleration, A man exerts a northwa...

A man exerts a northward force of 100 newtons on a 50 kilogram box which sits on a level floor. If the frictional force is 80 newtons. What is the magnitude of the northward

Nicol prism, Q.   Describes the construction of a 'Nicol Prism' and explain...

Q.   Describes the construction of a 'Nicol Prism' and explains its action in converting UPL into PPL. Sol.     Nicol Prism: This is the most simple and elegant polarizer and

Motion in one dimension , if joe rides his bicycle in a straigght line for ...

if joe rides his bicycle in a straigght line for 15 min with an average velocity of 12.5 km/h south how far has he ridden

Kinematics, how to solve kinematic problems?

how to solve kinematic problems?

Properties of the medium for wave propagation, Essential properties of the ...

Essential properties of the medium for wave propagation: (i)  Elasticity: So that particle can return to their mean position, after having been disturbed. (ii) Inertia : So t

Explain forward bias and reverse bias, Explain briefly, with the help of ci...

Explain briefly, with the help of circuit diagram, how V - I characteristics of a p-n junction diode are obtained ii (i) forward bias, and (ii) reverse bias. Illustrate th

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