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i basically know what the theory is about...cooper pairs and distorting...
but what does it contribute? like what does it explain?
but what does it contribute? like what does it explain?
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the BCS theory (1 Viewer)
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Dash
ReSpEcTeD
Basically, it explains how superconductivity works. The resistance in a metallic conductor is a direct result of electrons colliding with the imperfections within the crystal lattice. However, in superconductors (when at their critical temperatures) electrons pass unimpeded by the lattice - zero resistivity. The BCS theory explains this phenomenon!
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oh..
so:
in normal conductor...electrons do go past, but with resistance(little)
in superconductor(at critical state), electron go past, but no atoms in their path...hence why cooper pair past along, they actually distorting the structure of the positive pair...
right?
so:
in normal conductor...electrons do go past, but with resistance(little)
in superconductor(at critical state), electron go past, but no atoms in their path...hence why cooper pair past along, they actually distorting the structure of the positive pair...
right?
Dash
ReSpEcTeD
Yeh, basically...
The lattice structure of the superconductor at its critical temperature allows the Cooper Pairs to pass easily though the lattice.
The lattice structure of the superconductor at its critical temperature allows the Cooper Pairs to pass easily though the lattice.
Errr... I don't undertand what you're asking here
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ahh..poor wording, was in a rush to answer the phone..
distort the postive charges...
distort the postive charges...
Rahul
Dead Member
resitance comes from the electrons in the conduction band hitting the atomic structure of the lattice in the conductor. in a superconductor this is taken out of the equation.
in a normal conductor, the electrons hit the structure of the lattice [the atoms]. this doesnt happen in a superconductor and the bcs explains why this happens.
in a normal conductor, the electrons hit the structure of the lattice [the atoms]. this doesnt happen in a superconductor and the bcs explains why this happens.
Dash
ReSpEcTeD
Yup
When a superconductor is cooled, its lattice vibrations are reduced. However, the theory of superconductivity relies on the distortion of the lattice. Or in other words the "positive charges" (as you stated). But don't call them that in the exam!
Use the term "Positively Charged Ions", the examiners are bound to like it
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yea, but i was thinking what does all the distortion gotta do with it...
fark chem!!Originally posted by Dash
Use the term "Positively Charged Ions",
i hate chem!
*shakes fist*
Dash
ReSpEcTeD
The distortion of the lattice in the superconductor creates the postive attraction so that the cooper pair can be formed! The distortion of the lattice also assists in passing the cooper pair through the superconductor!
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i thought the cooper pair was join by this thing call phonon...
Rahul
Dead Member
what are you referring the "positive charged ions" to?
the atoms in the lattice or the area of strong positive field where the electrons pair up...
vibrations happen when the electrons collide the atoms in the lattice in a conductor.
distortions take place in the lattice of the superconductor.
these two are separate things....
the distortion doesnt allow for the vibrations to occur, due to the positive field in the supercondutor's lattice. they can distort since they are at the critical temperature.
the atoms in the lattice or the area of strong positive field where the electrons pair up...
there are two different things: distortions and vibrations.
vibrations happen when the electrons collide the atoms in the lattice in a conductor.
distortions take place in the lattice of the superconductor.
these two are separate things....
the distortion doesnt allow for the vibrations to occur, due to the positive field in the supercondutor's lattice. they can distort since they are at the critical temperature.
no they join because they are in a strong positive field. they dont exactly join, they come very close...once the positive field slowly gets taken away, one electron repels and shoots off....and the process is repeated with the remaining electron
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Constip8edSkunk
Joga Bonito
phonon is packet of acoustic energy from the vibration of the lattice that attracts the cooper pair together... the interchange of the phonon between the leading electron to the follower causes the pair to be constantly breaking and forming... this pulling action allows the pair to bypass resistance that under normal circumstances would have been caused by collisions wif the lattice.
Dash
ReSpEcTeD
I don't think that we have to talk about the acoustic variables that are emitted from the lattice vibrations. Isn't that out of the syllabus?
Hello There,
I guess you must be refering to the following dot point in the syllabus "describe the occurence in superconductors below the critical temperature of a population of electron pairs unaffected by electrical resistance" - which is the BCS theory.
Now, when a single elecron flows between two rows of lattice ions in a superconductor, the positive lattice ions are attracted inwards towards the electron. This generates a lattice distortion and an increased positive charge density TRAILING the electron as it moves through the lattice. It gfollows that an electron pair would be formed due to an electron close to the first one being attracted to the increased positive charge densitry behind the initial electron. These pairs of electrons involve low quatised energy states and are able to travel through the lattice unimpended - any more in depth knowledge of why this occurs and you have 1st year physics at uni!. These pairs are not formed when the critical temp is exceeded..
Hope this can help!
Cheers
I guess you must be refering to the following dot point in the syllabus "describe the occurence in superconductors below the critical temperature of a population of electron pairs unaffected by electrical resistance" - which is the BCS theory.
Now, when a single elecron flows between two rows of lattice ions in a superconductor, the positive lattice ions are attracted inwards towards the electron. This generates a lattice distortion and an increased positive charge density TRAILING the electron as it moves through the lattice. It gfollows that an electron pair would be formed due to an electron close to the first one being attracted to the increased positive charge densitry behind the initial electron. These pairs of electrons involve low quatised energy states and are able to travel through the lattice unimpended - any more in depth knowledge of why this occurs and you have 1st year physics at uni!. These pairs are not formed when the critical temp is exceeded..
Hope this can help!
Cheers