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

Explain about soft iron armatur, A force of 2.5kN is needed to lift a load....

A force of 2.5kN is needed to lift a load. How much work is done if the load is lifted by 500cm? An electromagnet exerts a force of 12N and moves a soft iron armature by a dist

Give three applications of photoelectric cells, Q. Give three applications ...

Q. Give three applications of photoelectric cells. (i) Photoelectric cells are utilized for reproducing sound in cinematography. (ii) They are utilized for controlling the

Function of photodetectors in fibre optic communication, Define the functio...

Define the function of photodetectors in fibre optic communication system. Photo-detectors: At the receiver end, conversion of optical signal into analog signal is being don

Explain process of resonance, Resonance: When the frequency of driving...

Resonance: When the frequency of driving force becomes equivalent to the natural frequency of an oscillating system, the driving force gives maximum energy and the oscillating

Liebig condenser (iron), Liebig condenser (iron) A piece of iron pipe l...

Liebig condenser (iron) A piece of iron pipe line as is used for water or electric conduit can be used to make a metal condenser which is much more robust than a glass one. Inl

Evaluate the maximum order of spectrum, A monochromatic light of wavelength...

A monochromatic light of wavelength 6000Å is incident on a plane diffraction grating with grating element 6 X 10 -5 cm. Evaluate the maximum order of spectrum that will be observe

Are side emitting fibers with reflecting core more luminous, Are the side e...

Are the side emitting fibers with reflecting core more luminous? To answer this honestly is very much as trying to find out the sex of the angels. When a side emitting light gu

Find out the wavelength of light, In a young's double slit experiment the s...

In a young's double slit experiment the screen is 1 meter away from the slit, the separation between the slits is 1mm and the distance between the 1st and 4th fringe is 1.2mm. Find

Ferro electric behavior of solids, In physics, the dielectric material such...

In physics, the dielectric material such as Rochelle salt and barium Titan ate with a domain structure containing dipoles (a symmetric distributions of electrical charge) which spo

What is waveguide dispersion in optical fibres, What is waveguide dispersio...

What is waveguide dispersion in optical fibres? Waveguide dispersion (Δτ w ): Waveguide dispersion occurs because of the dependence onto the velocity of propagation of every

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