Energy in inductor

Energy in an inductor

  • Changing current in an inductor gives rise to self induced emf which opposes changes in the current flowing through the inductor.
  • This self inductance thus plays the role the inertia and it is electromagnetic analogue of mass in mechanics.
  • So a certain amount of work is required to be done against this self induced emf for establishing the current in the circuit.
  • In order to do so, the source supplying current in a circuit must maintain Potential difference between its terminals which is done by supplying energy to the inductor.
  • Power supplied to the inductor is given by relation
    P=ξI                      ---(4)

    L is Self inductance and
    dI/dt is rate of change of current I in the circuit.
  • Energy dW supplied in time dt would be
    =LI(dI/dt) dt
    and total energy supplied while current I increases from o to a final value I is

  • Once the current reaches its final value and becomes steady ,the power input becomes zero.
  • The energy so far supplied to the inductor is stored in it as a form of potential energy as long as current is maintained.
  • When current in circuit becomes zero, the energy is returned to the circuit which supplies it.

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