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

Electrostatics, what is dielectric polarisation

what is dielectric polarisation

Dual power supply, what is a dual power supply?

what is a dual power supply?

Calculate output voltage of the Infra-Red detector?, Infra-Red (IR) Detecto...

Infra-Red (IR) Detectors: An IR detector has an impedance of Z= (400+j200) ? . During design tests the detector current is measured as 4 µA. What is the output volta

Determine the power dissipated in the load, (a) A current of 15A fl ows th...

(a) A current of 15A fl ows through a load having a resistance of 4Ω . Determine the power dissipated in the load. (b) A wattmeter, whose current coil has a resistance of

Applications of electrostatic shielding, what is electrostatic shielding

what is electrostatic shielding

Critical temperature in superconductors resistance , why at critical temper...

why at critical temperature in superconductors resistance becomes zero? Solution) For conductors as the temperature increases their rasistance increases and as temperature decreas

What is incorrect with this picture, What is incorrect with this picture? ...

What is incorrect with this picture? Answer: The Current is the flow rate of charge. When the charge obtains to the junction of three wires (including the wire the

Clamper, assignment of clamper

assignment of clamper

Comparison among types of harmonic motion, Can you give the graphical compa...

Can you give the graphical comparison among the following three kinds of harmonic motion: i. Under damped harmonic motion ii. Over damped harmonic motion iii. Critically

Magnetic moment of a semi circular magnet, What do you mean by the magnetic...

What do you mean by the magnetic moment of a semi circular magnet of radius ‘r' and pole strength ‘m'

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