Population Inversion in Lasers - A Level Physics

This video explains population inversion in lasers for A Level Physics.
In order to allow an increase in the total number of photons emitted by a sample there needs to be more atoms held in the high energy excited state. If there are more atoms in an excited state than in the ground state, this is called a population inversion. In order to achieve a population inversion we have to do something called optical pumping which I explain in the next video.
I used this as a reference: www.wjec.co.uk/...
Thanks for watching,
Lewis
This video is recommended for anyone studying A Level Physics in the following exam boards:
Eduqas
WJEC
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[@mengziyue4574]

I don't know how is this even A-level topic....You explained much better than my Photonics lecturer in uni, no overdose of math that only causes confusion, only the raw, abstract concept.

[@zeinabrahmani963]

I think you should emphasize that for the stimulation emission to occur, the atom should be in the excited state. therefore when it is hit by a new photon, the atom will go to the ground state and 2 photons are generated (one from the hitting photon, the other from atom coming back to the ground state)

[@meghax4480]

Thank you so much, the concept is very well explained!

[@krishvasa7644]

Thanks a lot for the awesomeeee explanation!

[@alltime5244]

at 3:13 I think you mean electrons instead of atoms I'm not sure though I'm just finding this a bit confusing

[@alltime5244]

Brandon White thank you I appreciate the help

[@BZaks]

you are right he meant electrons, atoms don't move up and down energy levels

[@AfricanGotPace]

@@BZaks no the atoms absorb the photons which make electrons move up energy levels

[@alltime5244]

@First Name Update: I went from a D student to actually get a B (almost A :( )and I seriously attribute all of my success to this channel

[@joshuagardiner9096]

3:10 how come it doesn't go back down to ground state and release a photon?

[@joshuagardiner9096]

how come spontaneous emission doesn't take place?

[@natedrake85]

He stated that photons are absorbed by the level that has larger numbers of electrons

[@TheHHPodcast]

Sorry to tell you but this was actually quite confusing. It made me understand less