Demagnetizing Field Explained - What is It & How?

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Demagnetizing fields arise at the ends of bar magnets where the magnetic field strength (H) points opposite to magnetization (M) and magnetic flux density (B). This phenomenon is often misnamed, as it is actually B that influences atomic polarization in iron, not H. The strength of B at the magnet's ends is about half of its value at the center, leading to a gradual loss of magnetization (M) over time. Understanding these concepts is crucial for accurately discussing magnet behavior. The discussion highlights the importance of distinguishing between H and B in the context of magnetization.
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Can anybody enlighten me on what demagnetizing field is and how it comes to existence?
 
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At the end of a bar magnet, H points in the opposite direction to M and B. This is due to the boundary condition on H at the end of a magnet. In many books, this is called a
"demagnetizing field". That is a misnomer, because it is B and not H that acts to polarize the atoms in the iron. Since B near the end of the magnet is 1/2 its value at the middle, there is some tendency for the magnet to lose a bit of its magnetization (M) over time.
 
I'll try to absorb what you said, and then come back.
Thanks for your post
 

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