A point between 2 magnets, what remains constant at that point?

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Discussion Overview

The discussion revolves around the behavior of magnetic and electric fields at a fixed point between two magnets and two fixed charges, specifically questioning which quantities—magnetic field strength (H), magnetic flux density (B), magnetomotive force (MMF), electric field (E), electric displacement (D), and electromotive force (EMF)—remain constant when different materials are placed at that point.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions whether H, B, or MMF remains constant at a fixed point between two magnets when different materials are introduced.
  • Another participant expresses confusion about the original question, seeking a straightforward answer regarding the fundamental nature of electric and magnetic fields.
  • It is suggested that the shape and orientation of the material affect both B and H, indicating they will change in the vicinity of the material.
  • A participant asserts that none of B, H, E, or D are fundamental qualities, proposing that only MMF is the fundamental driver, while B and H vary with material properties.
  • A specific example involving a solenoid with an iron core and an air gap is provided to illustrate that while MMF leads to a constant magnetic flux, B remains the same across different materials, but H varies.
  • The participant speculates that similar principles apply to electric fields, suggesting D remains constant while E varies across different materials.

Areas of Agreement / Disagreement

Participants do not reach a consensus, with multiple competing views on which quantities remain constant and the fundamental nature of the electric and magnetic fields. The discussion remains unresolved regarding the core question posed.

Contextual Notes

Participants express uncertainty about the definitions and fundamental nature of the quantities involved, and the discussion includes assumptions about the effects of material properties on the fields.

ugenetic
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a fixed spatial point between 2 fixed magnets. if I place different blocks of material on that point, is the H that will remain the same? or is it the B? or just the MMF (magnetic motive force), while B and H will always change depend on the material placed?

the same question for E, D, and EMF between 2 fixed charges.

thanks
 
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I am sorry, I don't understand, was the question itself too naive? but I m just asking for a "yes" or "no" really. I was trying to understand the medium independent, fundamental driven force of E or M field.
 
It depends on the shape and orientation of the material.
Usually, both B and H will change in the vicinity of the material.
 
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And, both B and H will change at the point of interest INSIDE of the material as well right? The same applies for E and D too right?

So, none of B or H or E or D are "fundamental qualities". Only the EMF and MMF are. Meaning: only MMF ( N*i) is the fundamental "driver", while B and H will vary with the properties of different materials.

I was looking at a solenoid with an iron core inside. the iron core has an air gap inside. once the MMF was turned on, a constant flux will flow thru the core and air gap (ignore fringing), so B's are the same for air gap and core but H's are different.
I am guessing some similar situations would apply for E and D as well. D will remain the same thru out different materials but E actually varies.
 

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