Re: Faraday paradox redux

On Sun, 14 Sep 2008 22:18:12 -0700 Salmon Egg <SalmonEgg@xxxxxxxxxxxxx> wrote:

| Consider a planar square loop of wire in a horizontal plane. To be
| specific, assume the length of each side is one meter. Assume that a
| pair of strip magnets, say 0.5 cm thick by 5 cm by 20 cm is centrally
| placed above and below the wire making up one side of the square. The 5
| by 20 faces are horizontal. The strips are magnetized in the thickness
| direction (vertically). The combination puts the wire under the strips
| in a vertical magnetic field. A magnetic yoke is used to restrict the
| magnetic field mostly to the gap at the wire or inside the yoke.

So these strip magnets have the N/S orientation in the same direction?

Can you further define what this "magnetic yoke" is?


| If this whole combination is rigidly moved horizontally normal to the
| wire in the magnetic field, is an emf induced in the loop?

I would say no, that no EMF is induced. I say this because there is no
relative motion between wire and magnetic field.


| Compare to the rotating Faraday disk consisting of two magnets cemented
| to the conducting disk as it rotates.

I say there is no EMF induced in the disk in this version of Faraday's disk.
Faraday measured current in this case, but that current was the result of
EMF induced in the wires connecting at the disk axle and at the disk edge
brush, from the moving magnetic field of the rotating magnets.

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