带电粒子在复合场中运动,物理情景比较复杂。而要求粒子在运动中通过某个定点,会使题目的难度更大。此类问题是每年高考命题的热点之一。求解带电粒子过定点问题有法可循,现举例如下。一、带电粒子以典型运动过定点问题例1如图1所示,坐标系xOy位于竖直平面内,在该区域内有场强E=12N/C、方向沿x轴正方向的匀强电场和磁感应强度大小为B=2T、沿水平方向且 Charged particles in the complex field movement, the physical situation is more complicated. The particles are required to move through a fixed point, making the topic more difficult. Such problems is one of the hot topics in the annual college entrance examination. Solving the problem of charged particles over a point to follow, for example as follows. First, the charged particles to a fixed point over a typical case Problem 1 As shown in Figure 1, the coordinate system xOy located in a vertical plane, in the region with a field strength E = 12N / C, the direction of the positive direction along the x-axis uniform electric field And the magnetic flux density is B = 2T, along the horizontal direction and