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If there is a coil with an external core, would the polarization of the magnetic field inside it be the opposite of an internal core?

For example, in the image:

cores

If DC current were applied to the wire (black) would the two ferrite core/shell portions (red and blue) contain magnetic fields which added together or which ran in opposite directions?

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  • \$\begingroup\$ Your picture doesn't adequately describe the physical shape of each core. \$\endgroup\$
    – Andy aka
    May 22, 2019 at 12:55
  • \$\begingroup\$ @Andyaka Thought it did, but assume the red one is solid and the blue one is a tube containing the red one + coil. \$\endgroup\$
    – CoryG
    May 22, 2019 at 15:05
  • \$\begingroup\$ I think you might mean "polarity" rather than "polarization". Please be clear. If you are talking about polarization, has your question got something to do with an EM wave? \$\endgroup\$
    – Andy aka
    May 22, 2019 at 15:27
  • \$\begingroup\$ @Andyaka "polarization" and "polarity" are synonyms in the context used. \$\endgroup\$
    – CoryG
    May 22, 2019 at 15:31

1 Answer 1

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What you have drawn is a rough picture of a "pot core". The direction of the flux lines will be through the center and then out around the outside shell as shown in the cross section below.

enter image description here

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  • \$\begingroup\$ If the ends are left open (like a solid iron rod with a coil around that and a solid iron tube around that) would the rod and tube be magnetically polarized in the same or opposite directions? \$\endgroup\$
    – CoryG
    May 22, 2019 at 15:07
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    \$\begingroup\$ They would be opposite. At one end, if the inner rod was "south" the outer tube on that end would be "north." This is how the electromagnets are configured at junkyards to pick up old cars (with the other end closed.) \$\endgroup\$
    – John Birckhead
    May 22, 2019 at 16:30
  • \$\begingroup\$ Thanks, this is what I had suspected but wanted to make sure. \$\endgroup\$
    – CoryG
    May 22, 2019 at 17:18

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