Which statement correctly defines the RMS value of an AC voltage?

• A. AC voltage is the square root of the average AC value
• B. The DC voltage causing the same heating in a given resistor as the RMS AC voltage of the same value.
• C. The DC voltage equal to the peak value of the AC voltage
• D. The DC voltage that would produce twice the heating as the RMS value

Answer: (B)

RMS value represents the effective DC amount that would produce the same heating in a resistor as the AC waveform does over time. In other words, it is the DC voltage that, when applied to the same resistor, would dissipate the same average power as the AC voltage. For a sine wave, this effective value is V_rms = V_peak / sqrt(2). So the statement that matches this concept is that the DC voltage causing the same heating in a given resistor as the RMS AC voltage would produce. The other ideas aren’t correct because heating depends on the average of V squared, not the average value of the voltage itself, and using peak value or twice the heating does not capture that equal-power equivalence.