题目内容
一带负电的点电荷仅在电场力作用下,先后经过电场中的A. B两点,其v-t的图象如图所示。tA. tB分别是该电荷经A. B两点的时刻,则( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241613527363391.jpg)
A.
点的电势一定高于
点的电势
B.场强的方向一定从
点指向
点
C.
点的场强一定小于
点的场强
D.该电荷在
点的电势能一定大于在
点的电势能
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241613527363391.jpg)
A.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161352752300.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161353017309.png)
B.场强的方向一定从
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161353017309.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161352752300.png)
C.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161352752300.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161353017309.png)
D.该电荷在
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161352752300.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161353017309.png)
A
试题分析:从v-t图像中可以看出点电荷做匀减速直线运动,负电荷受到的电场力方向和电场方向相反,故电荷沿电场线方向运动,而沿电场线方向电势降落,故A点的电势高于B点电势,A正确,场强方向由A指向B,B错误,因为电荷做匀减速直线运动,所以电场力大小不变,故为匀强电场,C错误,电场力做负功,电势能增大,故A点的电势能小于B点的电势能,D错误
点评:做本题的关键是从v-t图像中分析出电荷的运动性质,结合电场规律分析解题
![](http://thumb2018.1010pic.com/images/loading.gif)
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