What is a key difference between volt-amps (VA) and watts (W) in electrical calculations?

In electrical calculations, the distinction between volt-amps (VA) and watts (W) is crucial for understanding power measurement in AC and DC systems. Watts measure real power, which indicates the actual power consumed by resistive loads in a circuit, while volt-amps measure apparent power, which is the product of the voltage and the current in an AC system without regard to the phase angle between them.

When dealing with AC circuits, components such as inductors and capacitors can cause the voltage and current to be out of phase, leading to a difference between real power (measured in watts) and apparent power (measured in volt-amps). The real power represents the useful work done, while apparent power represents the total power flowing in the circuit, regardless of how much of it is being converted into useful work.

In contrast to the correct answer, other options incorrectly describe the relationship between VA and watts. They imply erroneous conditions about how these measurements apply to different power types or loads. Recognizing this distinction is essential for accurate load calculations, particularly in designing electrical systems efficiently.