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

Calculation of number of atoms per unit cell, Calculation of number of atom...

Calculation of number of atoms per unit cell The number of atoms per unit cell occurs on the crystal structure and the kind of basic elements (basis or pattern unit or motif) t

Determine the current taken by the capacitor, A motor has an output of 4.8k...

A motor has an output of 4.8kW, an efficiency of 80% and a power factor of 0.625 lagging when operated from a 240V, 50Hz supply. It is needed to improve the power factor to 0.9

What are the particles that make up an atom, Q. Illustrate what are the thr...

Q. Illustrate what are the three particles that make up an atom? Answer:- Atoms are conjured of neutrons, protons, and electrons. The protons as well as neutrons are found

Can illuminators be computer controlled, Can illuminators be computer contr...

Can illuminators be computer controlled? Practically all can be computer controlled as well as illuminators are not an exception. Color discs, mechanical shutters and lamp volt

Illustrate heterogeneous and homogenous systems, ‘q' is a path function. Un...

‘q' is a path function. Under what situations it will be a state function? Define and illustrate heterogeneous and homogenous systems with examples.

What do you mean by dispersion, What do you mean by dispersion? Describe a ...

What do you mean by dispersion? Describe a physical quantity which depends only on the material of the prism for its dispersion. Get an expression for it.

What do you mean by pure spectrum, What do you mean by pure spectrum? What ...

What do you mean by pure spectrum? What is an impure spectrum?

Simple harmonic motion i, Simple Harmonic Motion I Demonstrating in whi...

Simple Harmonic Motion I Demonstrating in which one component of uniform circular motion is simple harmonic motion.

What is the band width?, A data transmission rate; the maximum amount of in...

A data transmission rate; the maximum amount of information (bits/second) that can be transmitted along a channel is called band width.

Seebeck effect, a) Here temperature difference of junction is used to produ...

a) Here temperature difference of junction is used to produce thermo e.m.f. and vice-versa. b) This effect produced when junctions of a thermocouple are kept at dissimilar tempe

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