When measuring an AC voltage with a digital multimeter, what value is typically shown on the display?

When measuring an AC voltage with a digital multimeter, what value is typically shown on the display?

• A. Peak value
• B. RMS value
• C. Average value
• D. DC value

Answer: (B)

AC voltage readings on a digital multimeter are shown as the RMS value—the effective voltage that would produce the same heating in a resistor as a DC voltage. This is the quantity used for power calculations, not the peak or the average of the waveform. For a sine wave, the RMS value is the peak value divided by √2 (about 0.707 of the peak). So if the waveform peaks at 10 V, the display shows about 7.07 V. Some meters that aren’t true RMS meters may approximate RMS for sine waves, but the typical display for AC voltage is the RMS value.

AC voltage readings on a digital multimeter are shown as the RMS value—the effective voltage that would produce the same heating in a resistor as a DC voltage. This is the quantity used for power calculations, not the peak or the average of the waveform. For a sine wave, the RMS value is the peak value divided by √2 (about 0.707 of the peak). So if the waveform peaks at 10 V, the display shows about 7.07 V. Some meters that aren’t true RMS meters may approximate RMS for sine waves, but the typical display for AC voltage is the RMS value.