题干

如图所示,固定放置在同一水平面内的两根平行长直金属导轨的间距为d,其右端接有阻值为R的电阻,整个装置处在竖直向上磁感应强度大小为B的匀强磁场中.一质量为m(质量分布均匀)的导体杆ab垂直于导轨放置,且与两导轨保持良好接触,杆与导轨之间的动摩擦因数为μ.现杆在水平向左、垂直于杆的恒力F作用下从静止开始沿导轨运动距离l时,速度恰好达到最大(运动过程中杆始终与导轨保持垂直).设杆接入电路的电阻为r,导轨电阻不计,重力加速度大小为g.则此过程(   )

A:杆的速度最大值为 (F−μmg)Rd2B2

B:流过电阻R的电量为 BdlR+r

C:恒力F做的功与摩擦力做的功之和等于杆动能的变化量

D:恒力F做的功与安培力做的功之和大于杆动能的变化量

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答案(点此获取答案解析)

B,D

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