电功率是初中物理教学中一个重要的知识点．帮助学生理解用电器的功率,是教学的重要任务之一．用电器的功率分额定功率和实际功率．以电灯发光为例,当灯泡两端加上额定电压时,灯泡正常发光,这时它的电功率叫额定功率．灯泡实际消耗的功率叫实际功率．如果是在额定电压下工作,用电器的实际功率就等于额定功率；如果两端的电压低 Electric power is an important knowledge point in junior high school physics teaching. Helping students understand the power of appliances is one of the important tasks of teaching. The rated power and actual power of the electrical appliance. Taking the light emission as an example, when the rated voltage is added to both ends of the bulb, the light bulb will emit light. At this time, its electric power is called rated power. The actual power consumed by the bulb is the actual power. If it is working at rated voltage, the actual power of the appliance is equal to the rated power; if the voltage at both ends is low