## Root Mean Square or |

The square root of the average of the squares of a variable quantity.

In terms of voltage, the root mean square voltage is called the *effective voltage,* as opposed to the *peak
voltage* which corresponds to the maximum amplitude of the voltage variations.
*RMS power* (in watts) is similarly called the *effective power,* since for an amplifier, for instance, it represents its real power. See: Sound Pressure.

The following relationships hold between peak, rms and average voltage. Note that the so-called peak-to-peak voltage is twice the peak voltage.

rms voltage = 0.707 peak voltage |
rms voltage = 1.11 average voltage |

peak voltage = 1.414 rms voltage |
peak voltage = 1.57 average voltage |

average voltage = 0.637 peak voltage |
average voltage = 0.9 rms voltage |

Relative levels of average, RMS and peak voltages in a sine wave signal.