Electrical Engineering ⇒ Topic : Inductance

INDUCTANCE

Consider a coil of N turns which is carrying a current of I amperes as shown in Fig. (a). It is known from the previous sections that any current carrying coil will be associated with a flux. Let the flux associated with the coil be Φ.

                                      FIGURE (a) Flux due to a coil of N turns

     The flux linkages of the coil (Φ N) is equal to the product of the flux linking with the coil and the number of turns, i.e. Φ .N. Then, L = flux linkages/unit current = Φ N/L.

     L is said to be the inductance of the coil in henries. When Φ is expressed in Webers and / in Amperes, then the unit of inductance is henries. "A coil is said to be having an inductance of one henry when a current of one ampere produces a flux linkage of one weber-turn". The unit "henry" is abbreviated by symbol H.