RMS voltage enables power dissipation calculations in AC circuits that are comparable with DC circuits.

RMS voltage enables power dissipation calculations in AC circuits that are comparable with DC circuits.

• A. True
• B. False
• C. Only for pure resistive
• D. Only at high frequency

Answer: (A)

RMS voltage represents the heating effect of an AC waveform, which is what power dissipation depends on. For a resistor, the instantaneous power is p(t) = v(t)^2 / R. When you average that over a full cycle, you get P_avg = V_rms^2 / R, exactly mirroring the DC case where P = V^2 / R. This is why you can treat the RMS value as the equivalent steady voltage that produces the same average heating, making AC power calculations comparable to DC. In circuits that aren’t purely resistive, the relationship includes a phase difference between voltage and current, and the average power becomes P_avg = V_rms I_rms cos(phi). If the load is a pure resistor, cos(phi) equals 1, reducing to the same DC-like form P = V_rms^2 / R. So RMS voltage is the right quantity for computing dissipation and comparing AC to DC power, not limited to a specific frequency or to purely resistive loads.

RMS voltage represents the heating effect of an AC waveform, which is what power dissipation depends on. For a resistor, the instantaneous power is p(t) = v(t)^2 / R. When you average that over a full cycle, you get P_avg = V_rms^2 / R, exactly mirroring the DC case where P = V^2 / R. This is why you can treat the RMS value as the equivalent steady voltage that produces the same average heating, making AC power calculations comparable to DC.

In circuits that aren’t purely resistive, the relationship includes a phase difference between voltage and current, and the average power becomes P_avg = V_rms I_rms cos(phi). If the load is a pure resistor, cos(phi) equals 1, reducing to the same DC-like form P = V_rms^2 / R. So RMS voltage is the right quantity for computing dissipation and comparing AC to DC power, not limited to a specific frequency or to purely resistive loads.