This lecture covers the concept of instantaneous power in electrical engineering, including active power, reactive power, and complex apparent power. It explains the formulas for calculating these powers and their relationships in single-phase AC systems. The lecture also delves into the definitions of active power, reactive power, and apparent power, highlighting their significance in power analysis. Additionally, it discusses the interplay between active and reactive powers, as well as the calculation of complex apparent power. The lecture concludes by exploring power types and their relationships with resistance in electrical systems.