where is the energy stored in a electromagnetic field?

Discussion in 'General Electronics Chat' started by leonheard, Apr 6, 2013.

  1. leonheard

    Thread Starter Member

    Jan 8, 2013
    correct me if am wrong.....

    a capacitor stores energy from its electric field

    and inductor (coil) stores energy from its magnetic field

    1. an inductor (coil) creates an electromagnetic field

    2. there is an electric field and magnetic field in an electromagnetic field

    3. the energy is stored in the magnetic field, but… is the energy also stored in the electric field?

    am confused, please help, thanks ;)
  2. russ_hensel

    Well-Known Member

    Jan 11, 2009
    Basically the energy density is the square of the field strength ( within a constant ). The two fields should be evaluated seperately. This is standard E and M.
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  3. Papabravo


    Feb 24, 2006
    There are also dynamics involved. One of the conclusions you can draw from Maxwell's equations is that a changing Electric Field gives rise to a Magnetic field, and a changing Magnetic Field gives rise to an Electric Field.

    The Energy storage idea comes from the ability of a field to do "work".
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  4. kiroma


    Apr 30, 2014
    Are them perpendicular one from another? I think I learnt it in electromagnetism subject... Is it also known as "right hand rule"?
    Where the thumb is the force F, the index finger is the eletric field E and the "third" finger is the magnetic field M.
    Obs.: correct me if i'm wrong.
  5. Papabravo


    Feb 24, 2006
    The cross product of E and B is a poyinting vector which represents power. There is a rule that relates the charge, q and the velocity v of a particle in a magnetic field B that is a force. I think the electric field exerts a force along or opposite to the field lines depending on the sign of the charge.
  6. BR-549

    Well-Known Member

    Sep 22, 2013

    You are not alone. It's the way they teach you.

    A capacitor does not store energy in an electric field.

    An inductor does not store energy in a magnetic field.

    These passive devices store energy in an electric and magnetic field(EM field).

    These two components are always together, always equal and always cockeyed(perpendicular).

    The energy is stored by expanding these two components.

    The energy is released by contraction of these components.

    It's like a balloon being expanded and contracted.

    In most common circuits, the balloon expands and contracts at an equal rate.

    But if you expand the balloon and let it go....so it can contract very quickly(collapse), the balloon will fly across the room like it was kicked.

    We can do the same with a capacitor or an inductor, and we can get an electric-magnetic kick.