在电学问题中,常会遇到求解有关电源的输出功率和效率这类题目,学生常常对此问题没有全面清楚的理解而出现各种错误,为此,本文就这一问题作如下的探讨分析.图11.如图1所示,当电源的电动势E和内阻r一定时,电源的输出功率为:P出=I2R=(R+Er)2R=E2R(R-r)2+4Rr=(R-rE)22R+4r.(1)可见 In electrical problems, often encountered problems such as solving the power output and efficiency of the power supply, students often do not have a clear understanding of this issue and there are various errors. Therefore, this article discusses this issue as follows. Figure 11. As shown in Figure 1, when the E of the power supply and the internal resistance r are constant, the output power of the power supply is: Pout=I2R=(R+Er)2R=E2R(Rr)2+4Rr=(R- rE) 22R+4r. (1) visible