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Nov25-12, 11:41 AM
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Electric field produced by a magnet

Quote Quote by arul_k View Post
Thanks sophiecentaur for your reply. I am aware that a varying magnetic field is required to induce a current in a conductor, however in the case of super conductors this dosen't seem to be so.
For example in some of the videos that demonstrate the Miessner effect a permanent magnet is placed on top of the super conducting surface, there is no relative motion or changing flux between the magnet and the superconductor, yet when the superconductor is cooled down, a current is induced in it, which as you have stated does not die away.

My question is how can a non varying magnetic field induce a current in the super conductor?
There was a varying field to start with - when the magnet was brought into position or the current was turned on with the electromagnet. Once the current was established (due to this field being introduced) it carried on. (In fact this is what I have already said - and that is your reason.) Energy was put in and it stays there.