Impedance

Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now: https://www.khanacademy.org/science/e... The general notion of the ratio of a sinusoidal voltage to a sinusoidal current is called "impedance". We derive the impedance of a resistor, inductor, and capacitor. The impedance of the inductor and capacitor has a term for frequency, so the impedance of these components depends on frequency.