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 concepts of light, Theory of Light: Newton proposed 'Corpuscular...

Theory of Light: Newton proposed 'Corpuscular Theory of Light'. 2. According to corpuscular theory, light consists of a stream of tiny, light and perfectly elastic particle

Determine the weight of a body, Determine the weight of a body. Princip...

Determine the weight of a body. Principle: When a spring is fixed at one end and a force is applied to the other end the stretching of the spring is proportional to the applie

The physics of the brain, in need of projects on '' PHYSICS OF THE BRAIN''....

in need of projects on '' PHYSICS OF THE BRAIN''. Thanks

What is attenuation, What is Attenuation? Attenuation: Attenuation i...

What is Attenuation? Attenuation: Attenuation is a reduction within the amplitude and intensity of a signal. This is a significant property into optical communications. This

Vernier calipers, how does a Vernier caliper work

how does a Vernier caliper work

Relation between the electric displacement and current, Derive the relation...

Derive the relation between the magnitude of electric displacement and displacement current.

D/a converter, what is virtual ground

what is virtual ground

How far will it skid, How Far Will It Skid? Most drivers' education cla...

How Far Will It Skid? Most drivers' education classes teach future drivers in which the stopping distance of a skidding car is in a straight line proportional to the square of

Photoelectric cell, A device which changes light energy into electrical ene...

A device which changes light energy into electrical energy is known as photoelectric cell. It is also known as photocell or electric eye.

Calculate depth of the water, A circular hole of radius r at the bottom of ...

A circular hole of radius r at the bottom of an initially full water container is sealed by a ball of mass m and radius R (>r). The depth of the water is now slowly decr

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