题目内容
一矩形线圈,在匀强磁场中绕垂直磁感线的对称轴转动,形成如图所示的交变电动势图象,试根据图象求出:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241718185014003.jpg)
(1)线圈转动的角速度;
(2)电动势的有效值;
(3)如果线圈的内阻是10Ω,把它跟一个电阻为990Ω的电热器连在一起组成闭合电路时,10min内通过电热器的电流产生的热量是多大?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241718185014003.jpg)
(1)线圈转动的角速度;
(2)电动势的有效值;
(3)如果线圈的内阻是10Ω,把它跟一个电阻为990Ω的电热器连在一起组成闭合电路时,10min内通过电热器的电流产生的热量是多大?
(1)105rad/s 、(2)14.1V 、(3)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824171818798482.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824171818798482.png)
试题分析:(1)(3分)由图象得,交变电动势的周期T=6×10
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824171819016259.png)
而周期
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824171819484625.png)
代入数值解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824171819718334.png)
(2)(3分)由图象得,交变电动势的最大值为Em=20V,
电动势的有效值
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824171819718659.png)
代入数值解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824171819952334.png)
(3)根据公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824171820389544.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241718209501946.png)
点评:在计算热量的时候需要用到有效值,注意单位的转化
![](http://thumb2018.1010pic.com/images/loading.gif)
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