When voltage and current rise and fall at the same time, they are described as being in what state?

When voltage and current rise and fall at the same time, this phenomenon is described as being "in phase." In a phase relationship, the two waveforms reach their maximum and minimum values simultaneously, which means that the peaks and troughs of the waveforms align perfectly. This alignment allows for maximum power transfer in AC circuits, as the current and voltage are working together harmoniously.

This condition of being in phase is particularly important in power systems and AC circuit analysis, as it indicates efficient energy usage and minimal reactive power. Understanding this concept is essential for analyzing circuit behavior, designing systems, and optimizing performance to ensure that electrical components operate effectively together.

The other terms listed do not accurately describe this simultaneous behavior of voltage and current. "Out of phase" would imply that the two waveforms do not synchronize, resulting in a phase difference that leads to inefficient energy transfer. "In equilibrium" suggests a balanced state, but does not specifically address the timing of voltage and current. "Static" implies no change in state, which does not apply to rising and falling values of voltage and current.