6.1 Why Sinusoids?6.2 The Sinusoidal Source Function6.2.1 Amplitude, Period, Cyclic Frequency, Angular Frequency 6.2.2 Phase of a Sinusoidal Waveform6.2.3 Phase Difference Between Two Sinusoids 6.2.4 Lag or Lead? 6.2.5 Phase Lag/Lead Versus Time Delay/Advance6.3 Instantaneous Power in Periodic Waveforms6.4 Average Power in Periodic Waveforms 6.5 Effective Value (RMS Value) of Periodic Waveforms6.5.1 RMS Value of Sinusoidal Waveforms6.6 The Power Superposition Principle 6.6.1 RMS Value of a Composite Waveform 6.7 Summary6.8 Problems