论文部分内容阅读
根据部分电路欧姆定律,我们不难推出计算电功率的公式:P=IU,P=U~2/R,P=I~2R。从某种意义上(在纯电阻电路中)来说,这三个公式都成立,并且是等效的。但是,当应用它们来分析和计算有些问题的时候,很多同学就感到混淆不清了。例如,右图表示直流发电机给蓄电池充电的电路。电池组的电动势ε=6V,内阻r=0.1Ω,伏特表的读数是6.1V,求发电机的输出功率。
According to the Ohm’s law of some circuits, it is not difficult to introduce the formula for calculating the electric power: P=IU, P=U~2/R, P=I~2R. In a sense (in a purely resistive circuit), all three formulas are true and equivalent. However, when applying them to analyze and calculate some problems, many students are confused. For example, the figure on the right shows the circuit that the DC generator charges the battery. The electromotive force of the battery pack is ε=6V, the internal resistance is r=0.1Ω, the reading of the voltmeter is 6.1V, and the output power of the generator is sought.