题目内容
(8分)如图11所示,R为电阻箱,V为理想电压表,当开关S闭合,电阻箱读数为2Ω时,电压表示的读数为4V,当开关S断开时,电压表的读数为6V。求:
(1)电源的电动势和内阻
(2)当电阻箱读数为11Ω时,电源的输出功率为多大?![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241204050413338.jpg)
(1)电源的电动势和内阻
(2)当电阻箱读数为11Ω时,电源的输出功率为多大?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241204050413338.jpg)
(1)6V,1Ω
(2)2.75W
(2)2.75W
14.(1)S断开时:U="E=6V"
S闭合时:U=E-Ir
得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120405057450.gif)
所以r=1Ω
(2)电源输出电流
输出功率 P=I2R
解得 P="2.75W"
S闭合时:U=E-Ir
得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120405057450.gif)
所以r=1Ω
(2)电源输出电流
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120405073581.gif)
输出功率 P=I2R
解得 P="2.75W"
![](http://thumb2018.1010pic.com/images/loading.gif)
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