# AC circuits - inductors and resistors

Discussion in 'General Electronics Chat' started by xxxyyy, May 1, 2012.

1. ### xxxyyy Thread Starter Member

Oct 7, 2011
34
1
Hi!
Is there any tutorial about solving AC circuit which contains both resistors and inductors using kirchhoff laws?

2. ### bretm Member

Feb 6, 2012
152
24
The Kirchhoff analysis would be the same as if the inductors were replaced by resistors with resistance equal to their AC impedance (assuming their DC resistance is negligible). Impedance for an inductor is the inductance in henries multiplied by the angular frequency. The angular frequency is 2 pi times the AC frequency.

The AAC ebook gives an example at http://www.allaboutcircuits.com/vol_2/chpt_3/3.html

xxxyyy likes this.
3. ### xxxyyy Thread Starter Member

Oct 7, 2011
34
1
Thanks a lot!

4. ### crutschow Expert

Mar 14, 2008
21,381
6,125
That only works if the circuit contains only inductors and no resistors. If it contains resistors also then you have to do a complex impedance calculation to account for the phase shift caused by the inductors. That is shown in the reference you posted.

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5. ### xxxyyy Thread Starter Member

Oct 7, 2011
34
1
I have done few examples and I think I understand it. But if circuit has few voltage sources which have different frequencies, how should I solve that circuit? I guess that superposition theorem should do job?