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  4. Is there a magnetic "dead zone" somewhere between the two poles of a coil?
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Is there a magnetic "dead zone" somewhere between the two poles of a coil?

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Offline djc0245 (OP)

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Is there a magnetic "dead zone" somewhere between the two poles of a coil?
« on: 07/06/2008 18:22:53 »
Principle:    When using a coil for induction of a longitudinal magnetic field, the appropriate field strength selection is based upon the following formula:

                       I - Amperes required
     KD               K - 45,000 amperes turns
I = ----              L - Length of specimen
     NL               D - Diameter of Specimen (if solid)
                       N - Number of turns/wraps in coil

Effective area:   18 inches, 9 in. from center of coil/wrap both directions.
Given results:    Polarization of aligned electrons in specimen, N at one end, S at the opposite end.
Verified by:      Flux field leakage, demonstrated by lines of force at each end of specimen.

Inquiry:  Due to the lack of uniformity in most specimens' perimeter profile, Isn't there an existence of a neutrality point (maybe very narrow - almost indiscernible) in the center of the coil between the poles? Since a measurable reduction of applied field strength exists there? And shouldn't there be an established theoretical or industrial standard of identifying the neutral point, as a "Dead Zone"? Or for validity, at the least establish the practice of repositioning specimens?

<Mod edit - email removed, feel free to contact through this thread of private message. However, if you're really fond of spam, feel free to replace your address>
« Last Edit: 09/06/2008 10:25:07 by chris »
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Offline Bored chemist

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Re: Is there a magnetic "dead zone" somewhere between the two poles of a coil?
« Reply #1 on: 08/06/2008 14:11:48 »
Good question and I don't know the answer.
But I strongly advise you to remove your email address before it gets spammed to death.
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lyner

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Re: Is there a magnetic "dead zone" somewhere between the two poles of a coil?
« Reply #2 on: 08/06/2008 22:13:43 »
The actual system description is a bit vague and I can't be sure what the actual question is  but my answer to the question as I understand it is:
I don't think there is any likelihood of a 'neutral point' (do you mean 'null')
The field might be a bit non-uniform along the axis of the coil due to  the finite spacing between the turns  but Ampere's Law, I think, precludes having nulls .
Perhaps a diagram would help to make the question more clear.
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Is there a magnetic "dead zone" somewhere between the two poles of a coil?
« Reply #3 on: 11/06/2008 08:10:51 »
No.  The magnetic field runs substantially uniformly along the axis of the coil.  outside the coil the field loops back substantially like a bar magnet.  Magnetic "poles" in this context are rather ill defined areas in the vicinity of the ends of the coil.
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Is there a magnetic "dead zone" somewhere between the two poles of a coil?
« Reply #4 on: 11/06/2008 09:17:52 »
A field line is the route that an unnattached N pole with no mass would follow, so it would go straight from the North end of the coil to the south end very rapidly.

[diagram=353_0]

But if you had two North poles near each other then there would be a 'dead zone' of no field between them.
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Offline Atomic-S

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Is there a magnetic "dead zone" somewhere between the two poles of a coil?
« Reply #5 on: 13/06/2008 04:41:16 »
The field inside a coil is nowhere zero.
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Offline qazibasit

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Is there a magnetic "dead zone" somewhere between the two poles of a coil?
« Reply #6 on: 13/06/2008 13:39:54 »
good numerical and a real nice effort.
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