structural:summarization
Power

The relationship between voltage and the power delivered is:

where R {\displaystyle R} represents a load resistance.

Rather than using instantaneous power, p (t) {\displaystyle p(t)}, it is more practical to use a time-averaged power (where the averaging is performed over any integer number of cycles). Therefore, AC voltage is often expressed as a root mean square (RMS) value, written as V rms {\displaystyle V_{\text{rms}}}, because

For this reason, AC power's waveform becomes Full-wave rectified sine, and its fundamental frequency is double of the one of the voltage's.