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A magnetic field can be thought of a vector field of force on electrons. Basically this can be thought of a some area that attracts or repels electrons.

It is said that inductors are able to "store energy" in a magnetic field. Similarly, reactive power is said to be "stored" in the magnetic field when AC current flows through a conductor.

How can this be possible if a magnetic field is just like some volume of force? It sounds like someone saying energy is being "stored in a gravitational field".

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    \$\begingroup\$ It is similar to storing energy in a gravitational field, which is actually one of the main ways we store energy: en.wikipedia.org/wiki/Gravity_battery \$\endgroup\$ Feb 7, 2023 at 20:12
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    \$\begingroup\$ en.wikipedia.org/wiki/Water_tower \$\endgroup\$
    – hobbs
    Feb 7, 2023 at 20:27
  • \$\begingroup\$ A magnetic field can be thought of a vector field of force on electrons. No. Basically this can be thought of a some area that attracts or repels electrons. No. Unthink all that. Energy is a great unifying concept in physics. If you want to find a crooked politician, follow the money. If you want to understand physics, follow the energy. Energy is stored in fields - gravitational, electrical, magnetic. I don't know how the universe does this, it just does. When you change the energy in a field, work is done, felt as a force if there's a displacement. \$\endgroup\$
    – Neil_UK
    Feb 7, 2023 at 20:34
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    \$\begingroup\$ Feeling a great disturbance in the force... \$\endgroup\$ Feb 7, 2023 at 21:39
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    \$\begingroup\$ If you pull on a spring, does it then contain stored energy? Let it go, and you'll know for sure that it certainly did. Storing energy in a magnetic field is not totally dissimilar to that. You add energy, and it pushes the field out of shape. Soon as it can, it wants to get back into that resting shape, and in doing so it releases the stored energy. \$\endgroup\$
    – Kyle B
    Feb 8, 2023 at 0:00

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Energy can be stored in a gravitational field. Think black hole mergers, mass is converted directly into gravitational field energy with changes in that field in the form of waves. The waves can do work on the rest of the universe by wiggling everything very slightly.

Inductors can convert a change in current (moving electrons and electric field the difference of which is voltage), to a magnetic field (and then back again).

How can this be possible if magnetic field is just like some volume of force?

Well, the magnetic field is not a 'volume of force' it's a volume of field. If you want to find the energy from the field contained in the volume you can integrate over the field and find out how much field you have and divide by the volume.

But the key thing is that fields can contain energy, and they can do work on other things.

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Lenz's law states that the voltage induced in an inductor will oppose the change in current through it. That is, changing current through the inductor will induce an strengthening or weakening of its magnetic field which will induce an opposing voltage across the terminals of the inductor. The energy needed to overcome this induced voltage and increase or decrease the current through the inductor will be subtracted from or added to the charges flowing through it. Bit of a hand-wavy answer, but you can read the Wikipedia article on inductors for a full-math treatment.

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