How is electric power typically measured in an electrical circuit?

Electric power in an electrical circuit is typically measured using a wattmeter. A wattmeter is specifically designed to measure the rate of energy transfer, which is defined as electric power. The measurement is expressed in watts, derived from the formula ( P = V \times I ), where ( P ) is power in watts, ( V ) is voltage in volts, and ( I ) is current in amperes.

This differentiates a wattmeter from other instruments, like a voltmeter or an ammeter. A voltmeter measures voltage, or potential difference, across two points in a circuit, and is expressed in volts. An ammeter measures the current flowing through a circuit in amperes. An ohmmeter, on the other hand, measures resistance in ohms. Each of these tools serves a specific function in electrical measurement, whereas the wattmeter is the only instrument tailored for direct power measurement.