题目内容
一正弦式交变电流的图像如图所示.由图可知,该交变电流的周期为______s,频率为______Hz,电流的峰值为______A,有效值为______A.在0到0.02 s时间内,流过电路某一截面的电荷量为________,在这段时间内,流过电路电流的平均值为________.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824213135018602.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824213135018602.png)
0.02 50 6 3
0 0
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824213136360344.png)
试题分析:周期T和频率f是描述交变电流变化快慢的物理量,由图可知,周期T=0.02 s
故频率
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824213137156467.png)
该交变电流的峰值Im=6 A
故有效值I=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824213138232490.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824213136360344.png)
在0到0.02 s的时间内,前0.01 s流过电路的电流为正向,后0.01 s流过电路的电流为负向.由对称性可知,两段时间内流过电路的电荷量等大、异号,故0到0.02 s内流过电路的电荷量q=0.由平均电流的定义
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824213140541487.png)
点评:本题是交变电流图象,考查基本的读图能力.注意只有正弦式电流才有I=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824213138232490.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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