一、原题呈现22.(16分)两个半径均为R的圆形平板电极,平行正对放置,相距为d,极板间的电势差为U,板间电场可以认为是均匀的。一个α粒子从正极板边缘以某一初速度垂直于电场方向射入两极板之间,到达负极板时恰好落在极板中心。已知质子电荷为e, First, the original title presents 22. (16 points) two circular plate electrodes with radius R, placed parallel to each other, the distance d, the potential difference between the plates is U, the electric field between the plates can be considered uniform. An alpha particle enters the two plates from the edge of the positive plate at a certain initial velocity perpendicular to the direction of the electric field, and when it reaches the negative plate, it just falls on the center of the plate. Known proton charge is e,