### About Population Inversion in Laser - Definition, Diagram

Do you want to know about population inversion ? Here is the complete information on this topic of laser population inversion.In this we discuss in details on this topic.Laser light is totally different from conventional light.
In conventional light sources,there is no coordination among different atoms emitting radiation.
There will be a population inversion occurs where more atoms are present in high energy states than in low ones.

# Introduction

Population inversion is explained by levels E1, E2 and E3 of a system.Explain that E1, E2 and E3 are the excited states of ground state, metastable state, and system energies, respectively, such as E1 <E2 <E3. In a system, the population of atoms (N) at an energy level E, expressed at absolute temperature T .In terms of population (N1) in the ground state using Boltzmann's distribution law.

N = N1 exp (−E / KBT ) where KB = Boltzmann’s constant

 population inversion diagram

### Definition of Population inversion

Generally, the number of atoms (N1) present in the ground state (E1) in the system is larger than the number of atoms (N2) present in the high energy state. The process of making N2> N1 is called the population inverse.

#### Conditions for population inversion

These are the Conditions for population inversion :

(a) The system must have a pair of at least one energy level (E2> E1), separated by an energy equal to the energy of a photon (hν).

(b) There should be a continuous supply of energy to the system such that atoms must be continuously raised in excited state.

#### How Population inversion can be achieved

Population inversion can be achieved by following numbers of ways. Some of them are:
(i) optical pumping
(ii) electrical discharge
(iii) inelastic collision of atoms
(iv) chemical reaction and
(v) direct conversion.
In lasers, if the active medium is a transparent dielectric, the optical pumping method is used. If the active medium is conductive, the electric field is used to produce a population inverse.

### Biasing of p–n Junction | Forward and Reverse-biased |

Biasing the p-n junction means applying some external voltage to both sides of the p-n junction. Reverse-biased junction and forward-biased junction are two types of biased junction. You should have also good understanding of  N-Type and P-Type Semiconductor before moving towards this topic.

Biasing of p–n Junction Biasing of a p–n junction means uses of some external voltage across the two sides of the p–n junction. It is divided into two groups
Forward-biased junction : When the p-side of junction  is connected to the positive terminal of a battery and the n-side of junction is connected to the negative terminal, the p–n junction is said to be a forward-biased junction. Reverse-biased junction :If the positive terminal of the battery is connected to the n-side of junction and the negative terminal on the p-side, the p–n junction is said to be a reverse-biased junction.Now we will see about forward and reverse-biased junction in detail.
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If you are search about how to study science so i am going to share with you some tips that help you to study science in effective way. In this post, we are going to see what you should keep in mind while studying science. Because of which you can complete the syllabus of your science subject in the least time and comfortably and can  study  well with full concentration. So I will tell you five such tips with which you can study science comfortably.

How to study scienceWhether you are a student of class 10, whether in class 12 or any class, while studying science, these five tips will help you to get good score in science as well as improving your interests in science .

Goal Setting : By Goal Setting, I mean that when you sit for study, you have to set this target that today I will read so much chapter or today I will get up after reading so much content.This thing will do the work of positive motivation and will push you that we have to study till then. Until my target is achieved.
Rea…

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We see applications of electricity all around us.Today we will discuss about the need to study electrical  engineering .We observe the presence of electricity around us. This is really amazing and it is also interesting to know how mankind can power its use. All electronic and electrical products operate on electricity.  Be it your computer system, cell phone, home entertainment system, lighting, heating and air conditioning system - all are examples of electrical applications. The application of electricity is infinite and often extends beyond our imagination.

The need to study electrical engineering We have need to study electrical engineering because of following reason .Which is discussed below in given points.
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