What meter indicates true power in an AC circuit?

A wattmeter is designed specifically to measure true power in an alternating current (AC) circuit. It accomplishes this by calculating the product of voltage, current, and the power factor, providing a representation of the actual power consumed by the load. This is essential in AC circuits where the current and voltage may not be in phase due to reactive elements in the circuit.

In contrast, a voltmeter measures voltage, an ammeter measures current, and an ohmmeter measures resistance. While these devices can provide valuable information about an electrical system, they do not directly measure the true power being utilized. Therefore, the wattmeter is the only instrument among the choices that accurately reflects the real power factor in AC environments, making it crucial for electrical power analysis and management.