A sine wave with a peak value of 169.73 V has an RMS value approximately what?

A sine wave with a peak value of 169.73 V has an RMS value approximately what?

• A. 238.6 V
• B. 169.73 V
• C. 120 V
• D. 84.8 V

Answer: (C)

For a sine wave, the RMS value is the peak value divided by the square root of two. This comes from how RMS relates to the heating effect of a waveform, and for a pure sine, the factor is 1/√2. So with a peak value of 169.73 V, the RMS value is 169.73 / √2. Using √2 ≈ 1.414 gives about 120.0 V. That’s why the RMS value is approximately 120 V. The other numbers don’t fit the 1/√2 relationship: they would correspond to either the peak value or a different multiplier, not the RMS of a sine wave.

For a sine wave, the RMS value is the peak value divided by the square root of two. This comes from how RMS relates to the heating effect of a waveform, and for a pure sine, the factor is 1/√2.

So with a peak value of 169.73 V, the RMS value is 169.73 / √2. Using √2 ≈ 1.414 gives about 120.0 V. That’s why the RMS value is approximately 120 V.

The other numbers don’t fit the 1/√2 relationship: they would correspond to either the peak value or a different multiplier, not the RMS of a sine wave.