Question

What is RMS voltage in AC circuits?

Answer 1

RMS voltage, also known as Root Mean Square voltage, is a measure of the effective voltage in an alternating current (AC) circuit. In AC circuits, the voltage changes direction periodically, meaning it oscillates between positive and negative values over time.

The RMS voltage is a way to represent the equivalent steady DC (direct current) voltage that would produce the same amount of power dissipation in a resistive load as the AC voltage would. It is important because it allows for meaningful comparisons between AC and DC circuits, especially when considering the power consumption and heating effects in resistive components like resistors.

For a sine wave, which is the most common waveform in AC circuits, the RMS voltage can be calculated as follows:

RMS voltage (V_rms) = Peak voltage (V_peak) / √2

Where:

Peak voltage (V_peak) is the maximum amplitude of the sine wave.
√2 is the square root of 2, approximately equal to 1.414.

For example, if you have an AC voltage waveform with a peak voltage of 100 volts, the RMS voltage would be:

V_rms = 100 V / 1.414 ≈ 70.71 volts.

So, in practical terms, an AC voltage of 70.71 volts RMS would produce the same heating effect in a resistor as a steady DC voltage of 70.71 volts.