Alternating current (AC)

applied to an inductor

 


 

1) Suppose an alternating emf

is applied to an Inductor of inductance L. 

 



2) for an inductor, we know that the self-induce emf is




3) if

is the applied alternating emf then applying Kirchhoff’s loop rule:



 





On integrating, we get :




Where C is a constant of integration


Since C is a constant and it is independent from time, but at some moment emf and current becomes Zero. If C would be there then emf or current will never be zero, So C must be zero.



Therefore










Where



Therefore we see that in a circuit containing an inductor (L) the current (I)  is lag behind the alternating voltage by 




 

 

Phasor diagram of inductor

in an AC circuit:

 



 In phasor diagram for inductor in AC circuit the current is lag behind the voltage.