Originally posted by dr_rocket:
One of the basics of any problem solving or analytic activity is to ask what the object of study reminds you of.
My first level take on this is to think of charges moving in a magnetic field. This bring to mind the Lorentz force law: Fm = qv X B.
My second level take is to think about Faraday induction. This is where a magnet is thrust through a coil of wire to produce a current. I am also thinking of Lenz' law in this context.
Now I look back at the original question and notice that you said "superconducting charge carriers". Whoa! Shouldn't it be the charge carriers in the superconducting material?
Dr R.
Dr R. you have made my day. You gave the answer that you will find in all textbooks right up to the present. The currents are induced by Faraday's law of induction; even when the magnetic field is switched on over a material that is already in the superconducting state. An equivalent way would be to push a bar magnet towards the material. Now let us quote Feynman on this issue (Feynman lectures volume III pragraph 21-6): "If, as you build up the magnetic field, any of it were to build up inside the metal (in its superconducting state), there would be a rate of change of flux which would produce an electric field, and an electric field would immediately generate a current which, by Lenz's law, would oppose the flux".
Thus it is generally accepted, even by Feynman, that these currents are generated and driven by an electric field. There is only one problem: when an electric field drives a current, the material CANNOT be a superconductor. To be a superconductor a current must flow without any electric field responsible for the flow, or else, according to Ohm's law, the potential between two contacts cannot be zero; and therefore the resistance cannot be zero.
Why did the hundred's of thousand's of PhD students and their supervisors not pick up this impossibility over the last 70 years?
I have a good reason for using "superconducting charge carriers" which I will not elaborate on just now.
