It has been demonstrated that reactance opposes current flow in AC circuits. This is similar to how resistance opposes current flow in DC circuits which you have encountered in an earlier module, 38EEF. 

We can now combine the idea of resistance and reactance in a new term called impedance.

Impedance is a phasor equivalent of "resistance" in an AC circuit and is obtained by dividing the voltage phasor by the current phasor of the circuit:

Impedance can also be expressed in polar or rectangular forms (R represents resistance and X represents reactance):

Graphical summary

Revisit an earlier video for a quick recap of the concepts of phasors, reactance and impedance. 

Give it a try before referring to the solution video.