题目内容
(1)电动机的输出功率是多少?
(2)如由于某原因电动机被卡死,则灯泡亮度怎么变?(假设各元件仍在安全范围内,给出计算说明)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241201479481161.gif)
(1)
(2)灯泡的亮度将变暗
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120147979351.gif)
(1)
(2分)
(2分)
(2分)
(2)M、L并联等效电
(3分)
由分压原理易得此时L上电压为
(2分)
此时灯泡功率
(2分)
PL/<P额,所以灯泡的亮度将变暗。 (1分)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120148104665.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120148307670.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120148401502.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120148416654.gif)
(2)M、L并联等效电
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120148479640.gif)
由分压原理易得此时L上电压为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120148494780.gif)
此时灯泡功率
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120148510661.gif)
PL/<P额,所以灯泡的亮度将变暗。 (1分)
![](http://thumb2018.1010pic.com/images/loading.gif)
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