题目内容
空间有一匀强电场,在电场中建立如右图所示的直角坐标系
,M、N、P为电场中的三个点,M点的坐标为
,N点的坐标为
,P点的坐标为
.已知电场方向平行于直线MN,M点电势为0,N点电势为1 V,则P点的电势为( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242147505971702.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824214745808516.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824214746962517.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824214748179537.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824214749396592.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242147505971702.jpg)
A.![]() | B.![]() |
C.![]() | D.![]() |
D
试题分析:根据题意已知电场方向平行于直线MN,点M的电势为0,点N的电势为1V,故
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824214755542955.png)
将电场强度沿着-x方向和+y方向正交分解,设合场强为E,则-x和+y方向的分量分别为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824214756915886.png)
设P在x0y平面上的投影为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824214757992326.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824214758865572.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242147597391420.png)
又因N点电势为1V,则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824214757992326.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824214754326500.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824214754326500.png)
故选:D
点评:本题关键运用正交分解法,将电场沿着坐标轴方向正交分解,然后由
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824214804559534.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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