For a full-wave rectifier, the rectified output voltage waveform consists of the absolute values of the input AC voltage waveform. The RMS value of the output voltage is calculated as:
\[
V_{\text{rms}} = \sqrt{\frac{1}{T} \int_0^T V_{\text{rectified}}^2 \, dt}
\]
Since the full-wave rectifier converts both halves of the alternating current waveform into positive polarity, the RMS value remains the same as that of the input AC voltage waveform:
\[
V_{\text{rms}} = \frac{V_0}{\sqrt{2}}
\]
Thus, the RMS value of the rectified output voltage is \( \frac{V_0}{\sqrt{2}} \).