What is the fourth form of measurement of voltage and current associated with sine waves?

The fourth form of measurement of voltage and current associated with sine waves is RMS, or Root Mean Square. This method is significant because it provides a practical way to express the effective value of an alternating current (AC) waveform.

RMS is calculated by taking the square of the instantaneous values of the current or voltage over one complete cycle, averaging these squared values, and then taking the square root of that average. This process yields a value that represents the equivalent direct current (DC) value that would deliver the same power to a load. Therefore, when dealing with sine waveforms, the RMS value is essential for accurately determining the performance of electrical systems, especially in terms of power calculations and energy consumption.

The other options highlight different aspects of waveform measurement but do not serve as the standard for effective voltage and current readings in AC systems. Average values provide a mean level but can be misleading for sinusoidal waves. Peak-to-peak measurements give the total variation but do not reflect effective power. Frequency indicates how often the waveform cycles but does not pertain directly to voltage or current measurement. Thus, RMS is the key measurement for the effective values of sine waves.