If RMS value is 300 V, the peak value is about?

• A. 300 V
• B. 424.2 V
• C. 212.1 V
• D. 600 V

Answer: (B)

For a sinusoidal AC signal, the peak value is larger than the RMS value by the factor √2. The relationship is Vp = Vrms × √2. With Vrms = 300 V, the peak value is 300 × √2 ≈ 424.2 V. So the peak value is about 424.2 V.

The other numbers don’t fit the sine-wave relationship: 300 V would imply the peak equals the RMS, which isn’t true for a sine wave; 212.1 V is 300 divided by √2 and would be the RMS if the peak were 300 V, not the peak for 300 V RMS; 600 V is twice the RMS, which is not the correct factor for a sine wave.