the terms "electrical energy" and "electric power" are frequently used interchangeably. however, in physics, and electrical engineering, "energy" and "power" have different meanings. power is energy per unit time. the si unit of power and electricity is the watt. one watt is a joule per second. in other words, the phrases "flow of power," and "consume a quantity of electric power" are both incorrect and should be changed to "flow of energy" and "consume a quantity of electrical energy."