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

De?ne reduction potential and oxidation potential, De?ne reduction potentia...

De?ne reduction potential and oxidation potential. Reduction potential of a metal is the measure of tendency of a metallic electrode to gain electrons when it is in contact wit

If the ray is a principal ray where does it go from there, Portrayed is a r...

Portrayed is a ray from an object which heads toward and then into a lens. Suppose if the ray is a principal ray where does it go from there? Ans: This is the simple p

What do you mean by a zener diode, Illustrate the operation of NOT gate an...

Illustrate the operation of NOT gate and also provide its truth table. What do you mean by a Zener diode? Illustrate how it is used as voltage regulator.

Applications of radioactivity, how to prepare assignment for applications o...

how to prepare assignment for applications of radioactivity differently ?

What is eclipses, What is Eclipses? Sun is a luminous body while earth ...

What is Eclipses? Sun is a luminous body while earth and moon are non-luminous bodies. Only those parts of moon on the light of sun falls is visible. Also sun is larger than, b

State the conditions to achieve total internal reflection, Q. State the con...

Q. State the conditions to achieve total internal reflection. For entire internal reflection to take place (a) Light should travel from a denser medium to a rarer medium an

What are stark and zeeman effects, Q. What are Stark and Zeeman effects? ...

Q. What are Stark and Zeeman effects? It is found that while electric or magnetic field is applied to the atom all of the spectral line split into several lines. The former ef

Calculate the flowrate that is needed to produce a thrust, The thrust devel...

The thrust developed to propel the jet ski shown in Fig is a result of water pumped through the vehicle and exiting as a high-speed water jet. For the conditions shown in the Fig,

Fundamental postulates of special theory of relativity, Q. State the fundam...

Q. State the fundamental postulates of special theory of relativity? The two basic postulates of the special theory of relativity are: (i) The laws of Physics are the simila

Explain point charge - electric field, What are the magnitude and the sign ...

What are the magnitude and the sign of a point charge that experiences a force of   0.48 N east when placed in an electric   field of 1.6 x 10 5 N/C west? Normal 0

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