NATE Electrical Practice Exam 2025 – Complete Preparation Resource

Power in an electrical circuit is calculated using the formula P = VI, where P represents power measured in watts, V is voltage measured in volts, and I is current measured in amperes. This relationship comes from the definition of electrical power, which is the rate at which electrical energy is consumed or produced in a circuit.

When voltage and current are known, multiplying these two quantities yields the total power being used by the circuit. This formula is fundamental in electrical engineering and is applicable in various contexts, such as determining the power requirements of devices, ensuring that circuits are designed to handle adequate wattage, and optimizing energy consumption.

The other alternatives do not accurately represent how power is calculated. Simply adding voltage and current does not yield power; voltage and current have different units and cannot be combined in that way. The formula P = I/R is incorrect for calculating power and instead relates to Ohm's Law, while calculating power from voltage and resistance using P = V/R is not a direct representation of electrical power across a load without considering current. Additionally, multiplying voltage by resistance does not provide any value that represents power in a circuit. Therefore, the formula P = VI is the correct and universally accepted method for calculating electrical power.