I was reading about the energy stored in an Inductor and first of all I had the question that is this actually stored? The inductor produces a magnetic field which exerts a force on electrons. Isn't the energy spent on this?

While in a capacitor it doesn't exert any force as charges don't flow in between capacitors so I understood the energy stored in field of a capacitor. But I couldn't understand in an inductor. If someone could explain I would be grateful.


1 Answer 1


A constant current flowing in an ideal inductor produces a magnetic field which does not change as long as the current does not change. If an external effect tends to decrease the current, the the field strength decreases. The change in the magnetic flux produces an electromotive force in the coil which tends to maintain the existing current. In a capacitor, an external voltage forces charge onto the plates. If the voltage is removed, the charge looks for a way to get off of the plates.

  • $\begingroup$ This doesn't answer my question. Isn't the energy used up to produce an induced Emf $\endgroup$ Aug 15, 2020 at 7:49
  • $\begingroup$ Yes, the energy in the magnetic field decreases as it produces an emf and works to maintain the current. But note that the changing flux also produces an emf opposing the increase in current as the energy is building up in the magnetic field. $\endgroup$
    – R.W. Bird
    Aug 15, 2020 at 19:24

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