Which meter indicates the true power load in an AC circuit?

The wattmeter is the device designed specifically to measure the true power load in an alternating current (AC) circuit. It functions by taking into account both the voltage and the current in the circuit and their phase relationship, which is critical in AC circuits where these two quantities can be out of phase due to inductance and capacitance. This accurate accounting allows the wattmeter to provide a reading of real power, typically expressed in watts.

Other meters, such as the voltammeter and amperemeter, measure voltage and current, respectively, but do not directly assess the power consumed in a circuit. The ohmmeter is used to measure electrical resistance and does not pertain to power measurement in any way. Thus, the wattmeter is the appropriate choice for indicating the true power load, as it combines voltage, current, and the cosine of the phase angle between them to yield an accurate power measurement.