Question
What value of an AC signal produces the same power dissipation in a resistor as a DC voltage of the same value?
Answer Options
- A) The peak-to-peak value
- B) The peak value
- C) The RMS value
- D) The reciprocal of the RMS value
Correct Answer: C
Explanation
Alternating Current (AC) voltage is constantly changing, so its heating effect (power dissipation) is measured using an equivalent steady DC voltage. This equivalent value is called the Root-Mean-Square (RMS) value.
The RMS value of an AC voltage is mathematically defined as the value of DC voltage that would dissipate the exact same amount of average power in a purely resistive load. For a sine wave, the RMS voltage is approximately 0.707 times the peak voltage (V_{\text{RMS}} = V_{\text{peak}} / \sqrt{2}). This is the standard value used for most AC measurements, such as household voltage (120 \text{ V RMS}).
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