NEIEP Electrical Fundamentals (360) Practice Test

Power in electrical terms is the rate at which energy is transferred or consumed in a circuit. The standard relationship is P = V × I, meaning power equals voltage times current. The unit is the watt (W), defined as one joule per second, so in circuits P = V × I translates to watts (W = V × A).

You can also derive the other common forms from Ohm’s law. Since V = I × R, P can be written as P = I²R, or since I = V/R, P can be written as P = V²/R. All of these express power and, when computed correctly, yield watts as the unit.

The option P = V ÷ I would give a quantity with the unit of ohms (resistance), not power, so it isn’t power. Similarly, the forms P = I²R and P = V²/R are valid, but the unit must be watts, not amperes or newtons. Hence the correct match is P = V × I with the unit watts.