题目内容
(10分)如图所示,M为一线圈电阻RM=0.4Ω的电动机,R=24Ω,电源电动势E=40V.当S断开时,电流表的示数I1=1.6A,当开关S闭合时,电流表的示数为I2=4.0A。求
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250027295603282.jpg)
(1)电源内阻r
(2)开关S闭合时,通过电动机的电流及电动机消耗功率
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250027295603282.jpg)
(1)电源内阻r
(2)开关S闭合时,通过电动机的电流及电动机消耗功率
(1)
(2)
,![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002729607688.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002729576358.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002729591636.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002729607688.png)
试题分析:(1)当S断开时,只有电阻R连入电路,所以根据闭合回路欧姆定律可得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002729622698.png)
代入数据:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002729654773.png)
(2)当S闭合时,电阻R与电动机并联连入电路,根据闭合回路欧姆定律可得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002729669614.png)
解得此时路端电压为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002729685561.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002729700575.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002729716563.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002729732581.png)
所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002729591636.png)
电动机消耗的电功率:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002729763597.png)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002729607688.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目