Resistance, Reactance, and Impedance While studying DC circuit theory, you learned that resistance was an expression of a component's opposition to electric current. Then, when studying AC circuit theory, you learned that reactance was another type of opposition to current. Now, a third term is introduced: impedance. Like resistance and reactance, impedance is also a form of opposition to electric current. Explain the difference between these three quantities (resistance, reactance, and impedance) using your own words