题目内容
如图所示电路中,电源的电动势ε=16V,电阻R1=R2=R3=10Ω,电源内阻r=1Ω.求下述各种情况中电压表的示数(电压表的内阻非常大,流过电压表的电流可忽略不计).
(1)电键S接存a点.(2)电键S断开.(3)电键S接在b点.![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412572663515056.png)
(1)电键S接存a点.(2)电键S断开.(3)电键S接在b点.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412572663515056.png)
(1)外电路只有R2,R1被短路,电压表的读数是0。(2′)
(2)外电路是R1和R2串联,
(1′) ![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125726697554.png)
(1′)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728008568.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728023545.png)
(2′)
(3)外电路是R2和R3并联,然后与R1串联,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728398874.png)
(1′)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728538731.png)
(1′)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728585668.png)
(2′)
(2)外电路是R1和R2串联,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125726666727.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125726697554.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125726744519.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728008568.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728023545.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728055478.png)
(3)外电路是R2和R3并联,然后与R1串联,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728398874.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728413598.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728429438.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728538731.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728554657.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728585668.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125728616544.png)
略
![](http://thumb2018.1010pic.com/images/loading.gif)
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