题目内容
把带电荷量为+2×10-8C的点电荷从无限远处移到电场中A点,要克服电场力做功8×10-6J;若把该电荷从无限远处移到电场中B点,需克服电场力做功2×10-6J,取无限远处电势为零. 求:
(1)A点和B点的电势;
(2)将另一电荷量为-2×10-5C的点电荷由A点移到B点时电场力做的功.
(1)A点和B点的电势;
(2)将另一电荷量为-2×10-5C的点电荷由A点移到B点时电场力做的功.
(1)400V 100V (2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154008524555.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154008524555.png)
试题分析:(1)由电场力做功与电势差的关系得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241540086331483.png)
又
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154008758634.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154008820661.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241540089291433.png)
又
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154009116634.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154009366604.png)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154009506856.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241540096311020.png)
点评:注意求电势往往先求电势差,再求电势。
![](http://thumb2018.1010pic.com/images/loading.gif)
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