题目内容
一个由电阻均匀的导线绕制成的闭合线圈放在匀强磁场中,如图所示,线圈平面与磁场方向成60°角,磁感应强度随时间均匀变化,用下列哪些方法可使感应电流增加一倍( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241412154802770.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241412154802770.png)
A.把线圈匝数增加一倍 |
B.把线圈面积增加一倍 |
C.把线圈半径增加一倍 |
D.改变线圈与磁场方向的夹角 |
C.
设导线的电阻率为ρ,横截面积为S0,线圈的半径为r,则I=
=
=
=
·
·sinθ.可见将r增加一倍,I增加1倍,将线圈与磁场方向的夹角改变时,sinθ不能变为原来的2倍(因sinθ最大值为1),若将线圈的面积增加一倍,半径r增加到原来的
倍,电流也增加到原来的
倍,I与线圈匝数无关.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141215527440.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141215590718.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241412156361388.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141215699611.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141215777514.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141215886344.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141215886344.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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