Ohm's Law
The meaning of electrical impedance can be understood by substituting it into Ohm's law.
The magnitude of the impedance acts just like resistance, giving the drop in voltage amplitude across an impedance for a given current . The phase factor tells us that the current lags the voltage by a phase of (i.e., in the time domain, the current signal is shifted later with respect to the voltage signal).
Just as impedance extends Ohm's law to cover AC circuits, other results from DC circuit analysis such as voltage division, current division, Thevenin's theorem, and Norton's theorem can also be extended to AC circuits by replacing resistance with impedance.
Read more about this topic: Electrical Impedance
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“There was that law of life so cruel and so just which demanded that one must grow or else pay more for remaining the same.”
—Norman Mailer (b. 1923)