题目内容
一个正弦规律变化的交变电流的图象如图所示,根据图象计算:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241801522235064.jpg)
(1)交变电流的频率.
(2)交变电流的有效值.
(3)写出该电流的瞬时值表达式.
(4)电流的大小与其有效值相等的时刻.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241801522235064.jpg)
(1)交变电流的频率.
(2)交变电流的有效值.
(3)写出该电流的瞬时值表达式.
(4)电流的大小与其有效值相等的时刻.
(1)50Hz(2)14.1A(3)
(4)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180152489797.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180152738677.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180152239743.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180152489797.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180152738677.png)
试题分析:(1) 从图中可得T=0.02S,所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180153035756.png)
(2)根据有效值的定义可得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180153284888.png)
(3)根据公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180153518722.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180152239743.png)
(4)带入得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180153955822.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180152489797.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180152738677.png)
点评:关键是对公式的正确掌握,基础题,比较简单
![](http://thumb2018.1010pic.com/images/loading.gif)
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