# On the magnetic field in the Meissner effect

li dan
As shown in the figure, in the Meisner effect, the magnetic field of the magnet bypasses the superconductor. My question is, does the magnetic B field belonging to the magnet increase at the arrow indicating position?
Or is there no change in the intensity of the magnetic field that belongs to the magnet? Is it just the superposition of the magnetic field of the magnet and the magnetic field of the superconductor?.
Is it also possible to ask, assuming that the energized conductor is placed at the position of the arrow, regardless of the force between the energized conductor and the superconductor, the ampere force between the energized conductor and the magnet is F1. The ampere force between the energized wire and the magnet after removal of the superconductor is F2, can F1 be greater than F2?

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Gold Member
Yes, the local flux can increase due to the presence of the superconductor. This is known as "flux focusing".
Essentially, the field has to "go" somewhere to close the loop, and since it can't pass through the superconductor it has to go through the space in between.

Flux focusing can be quite significant; in many practical applications (e.g. superconducting coplanar waveguides) it can easily give you a factor ~10 increase.

li dan
li dan
Yes, the local flux can increase due to the presence of the superconductor. This is known as "flux focusing".
Essentially, the field has to "go" somewhere to close the loop, and since it can't pass through the superconductor it has to go through the space in between.

Flux focusing can be quite significant; in many practical applications (e.g. superconducting coplanar waveguides) it can easily give you a factor ~10 increase.

Thank you very much for your answer. Assuming that the energized conductor is placed at the position of the arrow, regardless of the force between the energized conductor and the superconductor, the ampere force between the energized conductor and the magnet is F1. The ampere force between the energized wire and the magnet after removal of the superconductor is F2. So, F1 may be bigger than F2, right?

li dan
Yes, the local flux can increase due to the presence of the superconductor. This is known as "flux focusing".
Essentially, the field has to "go" somewhere to close the loop, and since it can't pass through the superconductor it has to go through the space in between.

Flux focusing can be quite significant; in many practical applications (e.g. superconducting coplanar waveguides) it can easily give you a factor ~10 increase.
is to place the wire at the position of the arrow, the two ends of the wire connected to the battery into the current, the wire and the magnet between the Ampere force, in the case of superconductors and no superconductors, ampere force is different？

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