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

What is a calorie, What is a calorie? a)  Amount of heat needed to rais...

What is a calorie? a)  Amount of heat needed to raise one gram of water one degree Celsius. b)  Amount of work needed to move one gram of water by one centimeter. c)  Amo

Faradays law, Faraday's law The line integral of the electric field a...

Faraday's law The line integral of the electric field about a closed curve is proportional to the instant time rate of change of the magnetic flux by a surface limited by tha

Horizontal ray reflacted by prism, A horizontal ray hitting a prism with n=...

A horizontal ray hitting a prism with n=1.5, tip angle α=4 o . The ray will be deflected by an angle δ=(n-1)α. The ray is further reflected by a vertical mirror. Now, if I want to

Is light from object pass through the location of the image, In structuring...

In structuring the image does light from the object necessarily pass through the location of the image? Ans: No In reality in the case of a plane mirror (defining the obje

Explain energy, Energy is defined as internal capacity of doing work. When ...

Energy is defined as internal capacity of doing work. When we call that a body has energy we denote that it can do work. Energy seems in many forms such as electrical, mechanica

Algebra based physics 2.., A rectangular surface (0.14 m x 0.39 m) is orien...

A rectangular surface (0.14 m x 0.39 m) is oriented in a uniform electric field of 440 N/C. What is the maximum possible electric flux through the surface?

Calculate the refractive index of liquid, Focal length of convex lens is 0....

Focal length of convex lens is 0.1 m. A liquid lens is formed between a plane surface and one face of this lens of radius of curvature 0.12m. The converging combination formed is f

Question about antimatter, Hi i am doing research right now on anti-matter....

Hi i am doing research right now on anti-matter. I am just wondering if it is present in the human body?

Classification of matter , a pond is an example of

a pond is an example of

Volatility, It is the property of changing readily from a solid or liquid t...

It is the property of changing readily from a solid or liquid to a vapour. It is the speed that a chemical compounds evaporates. Higher volatility indicates faster evaporation.

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: +1-415-670-9521

Phone: +1-415-670-9521

Email: [email protected]

TERMS & POLICIES

HELP & SUPPORT

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd