题目内容
如图所示的电路中,当开关S1、S2均断开和均闭合时,灯泡L都同样正常发光.定出以下两种情况下流经灯泡的电流方向,即S1、S2均开启时 ;S1、S2均闭合时 .
(填“a→b”或“b→a”)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241308090914958.png)
(填“a→b”或“b→a”)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241308090914958.png)
.b→a a→b
当两开关都断开时,
和灯泡是串联在电路中,
无电流通过,所以电流方向从b到a,当两开关都闭合时,灯泡L与
并联后,与
串联,然后这三者再与
并联,所以电流方向从a到b。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130809169448.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130809200365.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130809512327.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130809200365.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130809637361.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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