# How does resistance differ from impedance?

But, in some alternating current circuits, where inductive and capacitative elements are present, they in addition offer an extra opposition to the flow of current due to the fact that they store magnetic and electrical energy respectively. This obstruction is quantitatively given by inductive reactance (X""_L) and capacitative reactance (X""_C).
$Z = {\left[{R}^{2} + {\left(X {\text{_C - X}}_{L}\right)}^{2}\right]}^{\frac{1}{2}}$