题目内容
标有“8V 6.4W”和“8V 20W”字样的a、b两只灯泡连接在如图所示电路中,
如果将电路中a、b两灯的位置互换,则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241242017412172.png)
如果将电路中a、b两灯的位置互换,则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241242017412172.png)
A.B点电势提高 |
B.B点电势降低 |
C.a灯变亮,b灯变暗 |
D.a灯变暗,b灯变亮 |
A
由
知,a灯电阻大,两灯串联,电流相等。C接地,电势为零,所以B点电势
。交换前
,交换后电流不变
,电势升高,A对B错。交换后电路电阻不变,电流不变,所以两灯亮度不变,CD错。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124201756602.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124201787589.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124202115754.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124202131770.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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