BCS Theory (1 Viewer)

[dude431]

I've read all the other threads on the BCS Theory and I still don't know whether or not I should include the explanation of phonons or leave it out completely. According to Emery the phonon stuff is not required, however Jacaranda has it in their explanation - which is not done very well, I might add, because it doesn't make complete sense.

 

[Tommy_Lamp]

some textbooks go into more detail then is required.

When im asked a question on it all i say is that at below the critical temperature the electrons pair up which allows them to travel unimpeded through the lattice and hence have no resistance, etc etc.

 

[za]

its part of the cooper pair thing.
just say wen the latice distorts it releases sound nenrgy in the form of phonons. the first electron absorbs this, the n releases it. the 2nde one absorbs the released energy, and it is this transfer of phonon energy that keeps the electrons together. the cloud if +ve charge that is formed overpowers the electrons initial repulsion, causing them to stay togethr.


i think thats all u need to know about phonons.

 

[Bob.J]

a phonon is a quantised lattice vibration

 

[Tommy_Lamp]

i dont think you need to know anything about the phonons.
the whole concept that they want you to understand is that the electrons pair up (cooper pairs), i dont think you need to know how they pair up

 

[kikujiro]

actually, i think you should learn about them...by being released they form the trough of positive ions around the elctron that attracts the second electron and accelerates them through - i thought that was one of the reasons why superconductors conducted so fast...but i could be wrong..?

 

[Constip8edSkunk]

it appeared in my trial last year so you should definitely learn about phonons, but then again you don't need to understand them(not at the high school level anyway) - typical of the HSC "if you can explain it to your dog then you learned something" style - so just regurgitate jacaranda or macmillan or something on it. search the forum about it as well if you want cuz it has been asked many times.

 

[ducksitter]

the syllabus only says: "discuss the BCS theory"
so you probably only need to say that phonons exist and they are the way the energy is transferred, nothing in depth. The important bit is you understand how BCS theory works and the implications.

 

[helper]

actually, i think you should learn about them...by being released they form the trough of positive ions around the elctron that attracts the second electron and accelerates them through - i thought that was one of the reasons why superconductors conducted so fast...but i could be wrong..?

Don't use the term ion or you will be marked wrong as they are not ions. Implies the material is positive overall. Similarly don't say n-type semiconductors are negative.

 

[BillyMak]

Talking about phonons is most definately not required.
My physics teacher has been on the board to write the physics HSC paper on several occasions, and is a senior marker. Overall, an excellent teacher. He has never talked about phonons at all, in fact the first time I have ever heard of them is in this thread.

 

[t-i-m-m-y]

dude431: be aware of the phonons, and what they do. however, you don't seem to be too confident about it, so i would recommend you leave it out if possible