Non-harmonic alternating currents

A. Boyajian: Professor Bedell is a pioneer in the theory of alternating currents, and his early book is still a classic on the subject. A few years ago I listened with great fascination to Professor Bedell narrating his early experiences in the fundamental theory of alternating currents. He said in the course of his narrative that when he analyzed the flow of currents in condensers, resistances and inductances due to sine-wave voltage, his mathematical analysis showed him that the current of the condenser should be 90 deg. ahead of the voltage, the current of the inductors 90 deg. behind, and in a resistance in phase with the voltage. Up to that time nobody knew anything about phase relationship and this was very puzzling. It was peculiar how in a condenser you could get current ahead of voltage, like having an effect precede the cause instead of following the cause. They made some tests, plotted oscillograms, verified the mathematical analysis and everybody was happy.