What type of values does an AC ammeter indicate?

An AC ammeter typically measures the effective (RMS) values of current. The effective current, or root mean square (RMS), provides a value that reflects the equivalent DC current which would produce the same amount of heat in a resistive load. This is particularly useful because it allows for a straightforward understanding of how much current will do work or produce heat, since AC current varies over time.

In circuits where AC current is used, the instantaneous current fluctuates above and below zero, making it necessary to use RMS values for practical measurements. The average value may not accurately represent the total current flow for non-sinusoidal waveforms, and peak values, while informative for particular characteristics of the waveform, do not provide a comprehensive measure of current over time for the purposes of most applications. Hence, the RMS value is the standard used in electrical engineering to denote the amount of current flowing in an AC circuit.