试题与答案

比面值

更新时间：2017-07-19 09:48来源：www.tikuol.com

题型：名词解释

题目：

比面值

答案：

参考答案：

某一物体单位体积所占有的表面积称为比面值。

考点：生物学微生物学微生物学题库

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题型：计算题

如图所示，在真空中，半径为R=5L₀的圆形区域内存在匀强磁场，磁场方向垂直纸面向里。在磁场右侧有一对平行金属板M和N，两板间距离为d=6L₀，板长为L=12L₀，板的中心线O₁O₂与磁场的圆心O在同一直线上。有一电荷量为q、质量为m的带电的粒子，以速度v₀从圆周上的a点沿垂直于半径OO₁并指向圆心的方向进入磁场平面，当从圆周上的O₁点水平飞出磁场时，给M、N板加上如下图所示电压，最后粒子刚好以平行于M板的速度，从M板的边缘飞出(不计粒子重力)。求

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(2)求交变电压的周期T和电压U₀；

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