Sinusoidally-excited circuits

Abstract

HITHERTO techniques for circuit analysis — and various useful theorems and transformations — have been illustrated using only direct voltages and currents. However, nearly all electricity is generated and consumed in the form of AC. In order to continue to use the methods devised originally for DC circuits, Heaviside¹ developed the use of complex numbers for currents, voltages and impedances. This has proved to be the most powerful tool ever put into the hands of electrical engineers.