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

How do you compute tensile strength, Q. How do you compute tensile strength...

Q. How do you compute tensile strength? Answer:- Tensile strength is not actually calculated it's measured. It is classified as the point at which a sample of material fai

Draw the final image formed by two lenses, Draw the final image formed by t...

Draw the final image formed by two lenses: An optical imaging system consists of two positive lenses (L1 and L2). L1 has a focal length f 1 = 10 cm, and L2 has a focal length

Searle''s apparatus, why metallic frame used in searles apparatus

why metallic frame used in searles apparatus

Dual power supply, what is a dual power supply?

what is a dual power supply?

Interference., expression for the interference in transmitted light through...

expression for the interference in transmitted light through thin films

Resonance, sharpness of resonance

sharpness of resonance

Linearr, linear polarizers whose transmission axes make an angle of 45degre...

linear polarizers whose transmission axes make an angle of 45degree with each other,.The transmitted light intensity through both polarizers is what percentage of the incident inte

Newton''s 2nd Law Question, m2, 8.5 kg, is accelerating down an incline at ...

m2, 8.5 kg, is accelerating down an incline at a constant rate. m1 is being pulled by a string attached between the two masses. The coefficient of friction between m1 and the horiz

What kind of batteries are used in tl coachees, What kind of batteries are ...

What kind of batteries are used in TL coachees. Briefly explain about each one of them? Ans. In TL coaches two kind of batteries are used. They are SMF and VRLA batteries.

Current and time? help!, If the current in a wire of a CD player is 14.0 mA...

If the current in a wire of a CD player is 14.0 mA, how long would it take for 1.90 C of charge to pass a point in this wire? Answer in units of s

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