题目内容
(16分)一个电阻为r、边长为L的正方形线圈abcd共N匝,线圈在磁感应强度为B的匀强磁场中绕垂直于磁感线的轴OO′以如图所示的角速度ω匀速转动,外电路电阻为R.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409446599148.png)
(1)在图中标出此刻线圈感应电流的方向.
(2)线圈转动过程中感应电动势的最大值有多大?
(3)线圈平面与磁感线夹角为60°时的感应电动势为多大?
(4)设发电机由柴油机带动,其他能量损失不计,线圈转一周,柴油机做多少功?
(5)从图示位置开始,线圈转过60°的过程中通过R的电量是多少?
(6)图中电流表和电压表的示数各是多少?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409446599148.png)
(1)在图中标出此刻线圈感应电流的方向.
(2)线圈转动过程中感应电动势的最大值有多大?
(3)线圈平面与磁感线夹角为60°时的感应电动势为多大?
(4)设发电机由柴油机带动,其他能量损失不计,线圈转一周,柴油机做多少功?
(5)从图示位置开始,线圈转过60°的过程中通过R的电量是多少?
(6)图中电流表和电压表的示数各是多少?
(1) dcba(2)Em=NBSω=NBωL2 (3)
NBωL2(4)
(5)
(6) ![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409449711259.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140944737170.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140944862460.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409449251998.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409449711259.png)
(1)由右手定则可判定电流的方向沿dcba.(2分)
(2)Em=NBSω=NBωL2 (2分)
(3)线圈平面与B成60°角时的瞬时感应电动势
e=Em·cos60°=
NBωL2. (2分)
(4)电动势的有效值E=
(1分)
电流的有效值I=
,柴油机做的功转化为电能,线圈转一周柴油机做的功
W=EIt=
t=
·
=
(2分)
(5)因为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409455801399.png)
故电量![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409456422100.png)
(6)电流表显示路端电压的有效值,则读数为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409457671280.png)
电压表显示路端电压的有效值,则读数为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409449711259.png)
(2)Em=NBSω=NBωL2 (2分)
(3)线圈平面与B成60°角时的瞬时感应电动势
e=Em·cos60°=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140944737170.png)
(4)电动势的有效值E=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140945065301.png)
电流的有效值I=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140945174269.png)
W=EIt=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140945237301.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140945393559.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140945439236.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140944862460.png)
(5)因为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409455801399.png)
故电量
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409456422100.png)
(6)电流表显示路端电压的有效值,则读数为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409457671280.png)
电压表显示路端电压的有效值,则读数为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409449711259.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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