Impedance

The impedance of a circuit refers to the total resistance of a circuit. This is different from the standard resistance, as it also includes the reactance - the imaginary part of the resistance. Impedance is indicated with a "Z". Note that the $j$ refers to the

• The Impedance of a Resistor is $R$.
• The Impedance of an Inductor is $jwL$.
• The Impedance of a capacitor is $1/jwc$

Where $j$ is $sqrt(-1)$. The reason $i$ isn't used is so we don't mix it up with current.

The rules for combining impedance are the same for combining normal resistors. (That you add Impedance in series, and you use the same method you normally use by parallel.) However extra caution should be taken regarding the $j$'s.