What does a wattmeter measure in an electrical system?

A wattmeter is specifically designed to measure power consumption in an electrical system, quantified in watts. This measurement is critical for understanding how much electrical energy is being consumed or transmitted in a circuit at any given moment. The wattmeter achieves this by calculating the product of voltage and current, taking into account the phase difference between them in cases where the circuit is alternating current (AC).

Measuring power instead of just voltage or current provides a more holistic understanding of the energy usage within a system. It allows technicians and engineers to assess efficiency, identify loading conditions, and ensure systems are operating within their designed parameters. Other options like voltage levels, current flow, or resistance, while important aspects of electrical systems, do not provide a direct measurement of power consumption, which is the primary function of a wattmeter.