Electric Circuits and Networks

7.3 INSTANTANEOUS POWER IN PERIODIC WAVEFORMS

A waveform v(t) is said to be periodic with a periodicity of T s if v(t + nT) = v(t) for all integer values of n and for all t. This implies that it must be possible to identify a basic section of the waveform that lasts for T s and that repeats to infinite extent into the past and into the future. Thus, a waveform is strictly periodic only if it is ever existent. But, in practice waveforms are switched on at some definite time instant. Such switched waveforms cannot be called periodic waveforms in the strict sense of definition of periodicity. However, we can view them as periodic waveforms for circuit analysis purposes provided we focus our attention to time instants located far away from the instant ...