How is electric power calculated in a wattmeter?

Electric power is calculated in a wattmeter by multiplying current and voltage. This relationship stems from the fundamental definition of electrical power in an electrical circuit, which is expressed as the product of the current (in amperes) that flows through a circuit and the voltage (in volts) across that circuit.

When you multiply these two quantities together, you obtain power measured in watts (W). The formula is given by:

Power (P) = Voltage (V) × Current (I)

This calculation is crucial because it allows engineers and technicians to determine how much electrical energy is being consumed or produced in a given electrical system.

In practical applications, wattmeters utilize this principle by measuring both the voltage and the current in the circuit to provide a direct reading of the power usage. Understanding this concept is vital for efficient power management and ensuring the safe operation of electrical systems.

The other choices do not accurately describe the method of calculating electrical power in a wattmeter, as they do not adhere to the correct relationship defined by electrical principles.