An AC ammeter indicates which type of current value?

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Multiple Choice

An AC ammeter indicates which type of current value?

In AC circuits the useful measure of current for heating and power calculations is the RMS value—the effective current that would produce the same heating in a resistor as a steady DC current of the same magnitude. An AC ammeter is calibrated to display this RMS value because power depends on I^2R, and the RMS current directly reflects that heating effect. For a sinusoidal current, the RMS value equals the peak value divided by the square root of two, which is why many AC readings are described in terms of this relationship. The average value over a cycle of a sine wave is zero, so it doesn’t represent the current that actually drives power in a circuit. The peak value tells you the maximum instantaneous current but not the typical heating effect. The DC component is the constant part of the current; pure AC has none, and a dedicated DC measurement would be required to read it. So the AC ammeter indicates the RMS (effective) current.

In AC circuits the useful measure of current for heating and power calculations is the RMS value—the effective current that would produce the same heating in a resistor as a steady DC current of the same magnitude. An AC ammeter is calibrated to display this RMS value because power depends on I^2R, and the RMS current directly reflects that heating effect. For a sinusoidal current, the RMS value equals the peak value divided by the square root of two, which is why many AC readings are described in terms of this relationship. The average value over a cycle of a sine wave is zero, so it doesn’t represent the current that actually drives power in a circuit. The peak value tells you the maximum instantaneous current but not the typical heating effect. The DC component is the constant part of the current; pure AC has none, and a dedicated DC measurement would be required to read it. So the AC ammeter indicates the RMS (effective) current.

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