题目内容
在匀强磁场中,有一接有电容器的回路,如图10所示.已知C="30" μF,l1="5" cm,l2="8" cm,磁场以5×10-2 T/s的速度增强.则 ( )?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241210062764784.jpg)
图10
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241210062764784.jpg)
图10
A.电容器上板带正电,带电荷量2×10-9 C |
B.电容器上板带正电,带电荷量6×10-9 C |
C.电容器上板带负电,带电荷量4×10-9 C |
D.电容器上板带负电,带电荷量6×10-9 C |
B?
根据Q=CU求带电荷量,两板电压
=5×10-2×8×10-2×5×10-2 V=2×10-4 V,Q=CU=30×10-6×2×10-4 C=6×10-9 C?
再由楞次定律判断得上板为正极板.因此带正电即B正确.?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241210062911870.gif)
再由楞次定律判断得上板为正极板.因此带正电即B正确.?
![](http://thumb2018.1010pic.com/images/loading.gif)
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