题目内容
如图所示电路中,两平行板A、B水平放置,两板间距离d=40cm, 电源电动势E=20V,内电阻r=1Ω,电阻R=3Ω。闭合开关s,待电路稳定后,将一带正电的小球从B板小孔以初速度v0=4m/s竖直向上射入板间。小球带电量为q=10-2C,质量为m=1×10-2kg,不考虑空气阻力。若调节滑动变阻器,使小球的最高点恰能达到两板中间,则电源的输出功率为( )[g=10m/s2]
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241304007852610.png)
A.36W B.51W C.57W D.64W
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241304007852610.png)
A.36W B.51W C.57W D.64W
A
小球的最高点恰能达到两板中间,
,计算得变阻器两端电压为12V,电路中电流
,电源的输出功率
,选A
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241304008321114.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130400988856.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241304010191245.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目