试题与答案

如图示,坐标系xoy位于坚直平面内,所在空间有沿水平方向垂直于纸面向外的匀强磁场

题型:计算题

题目:

如图示,坐标系xoy位于坚直平面内,所在空间有沿水平方向垂直于纸面向外的匀强磁场,磁感强度为B,在y﹥0的空间内还有沿x正方向的匀强电场。一质量为m的带电油滴沿着图中直线PQ做匀速直线运动,过Q点后油滴进入y﹤0的区域,图中θ=450。要使油滴在的y﹤0区域内做匀速圆周运动,需在该区域内加匀强电场。若带电油滴在y﹤0的区域内经过一段圆弧后再次通过x轴,并且能通过x轴上的M点(图中未画出),且Q、M两点间距离为L。求:

(1)油滴的带电性质。

(2)在的y﹤0区域内所加电场的方向。

(3)带电油滴所带电荷量q.

答案:

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