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Magnetism Strenght

Hi everybody! i need to know which is the equation for calculate the atraction or repulsion strenght of a magnetic field from a natural magnet or a coil, preferably the coil(repulsion when equal poles are confronted)... other thing, ¿Does increase the magnetic atraction when two opposite poles are confroted that when a single pole (of a magnet or coil) atracts a ferromagnetic material?! beforehand, thanks for any answer!

Reply to
Camilo Andres Gil Cardona
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To get started go to http://152.66.73.137/research/field/mam.html and then do some google searching on your own. Your questions are kind of "loaded."

Reply to
Charles Schuler

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In the most general terms, the force produced by any magnetic circuit depends on how much the total flux varies with the motion of the parts in question. If the flux changes more per unit of motion, the force is higher. Since the is no limit ot the geometric choices you have, there can be no simple mathematical rule to predict the force. The whole flux path and all its geometry has to be modeled.

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John Popelish
Reply to
John Popelish

Excellent answer John, but for the laymen here lets complicate things just a bit as a simple puzzle.

For the purposes of the puzzle, let's assume that we have a large "C" shaped magnet with a 3/4" spacing between its pole faces.

The questions:

  1. (easy) I we hold a 1/4" thick plate of mild iron midway between the ple faces, when we release it will it be attracted to the N pole or the S pole of the magnet? In other words, in which direction is the magnetic attraction?

  1. (requires a bit more thought) Assuming again that we hold the iron plate midway between the pole pieces, the magnetic flux path is though the magnet itself, then though a 1/4" airgap, through the iron plate, though another 1/4" air gap and then back into the body of the magnet itself. Why would the net flux be different when the iron plate is attracted to and in contact with one of the magnet's pole pieces, since the reluctance of the magnetic path appears to be the same in both cases? (The magnetic flux has to change for magnetic attraction to take place.)

I suppose you could call these brain teasers, but I do know of at least one graduate school admission exam in which question 2 appeared.

Have fun.

Harry C.

Reply to
Harry Conover

Good one. But what is the shape of the 1/4" thick plate? Knowing the phase of the moon might help too. ;-)

Why would you assume the reluctance is the same in both cases, unless you assumed the flux lines are parallel between the pole pieces, and this condition is unaffected by the presence of the iron plate.

But that would be a silly pair of assumptions. :-)

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John Popelish
Reply to
John Popelish

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