一、真题再现某装置用磁场控制带电粒子的运动,工作原理如图所示.装置的长为L,上下两个相同的矩形区域内存在匀强磁场,磁感应强度大小均为B,方向与纸面垂直且相反,两磁场的间距为d.装置右端有一收集板,M、N、PP为板上的三点,M位于轴线OO’上,N、P、P分别位于下方磁场的上下边界上.在纸面内,质量为m、电荷量为-q的粒子以某一速度从装置左端的中点射入,方向与轴线成30。角,经过上方的 First, the real question reproduce a device with a magnetic field to control the movement of charged particles, the working principle shown in Figure 1. The length of the device L, the upper and lower two identical rectangular regions exist uniform magnetic field, the magnetic flux density are B, the direction and the paper Perpendicular to the plane and opposite, the distance between the two magnetic fields is d. There is a collecting plate at the right end of the device, M, N and PP are three points on the plate, M is on the axis OO ’, N, P and P are respectively located on the upper and lower boundaries of the lower magnetic field In the plane of the paper, a mass of m and a charge of - q enters the midpoint of the left end of the device at a velocity of 30 in the direction of the axis. Angle, after the top