Inductance

An inductance is the element in which energy is stored in the form of electromagnetic field. The inductance is denoted as 'L' and is measured in henries (H).

       The fig shows an inductance. The time varying voltage v(t) is the voltage across it. It carries a current i(t) which is also time varying.

Fig.  1        Inductance

Key point : For an inductance, the voltage across it proportional to the rate of change of current passing through it.

       The constant of proportionality in the above equation is the inductance L.

      If the voltage v(t) is known across an inductor then the current is given by,

       If the inductance has N turns and the flux φ produced by the current i(t) entirely links with the coil of  N turns the according to Faraday's law,

       The total flux linkage Nφ are thus proportional to the current through the coil.

      The power in the inductor is given by,

       The energy stored in the inductor in the form of an electromagnetic field is,