带电粒子在有界匀强磁场中运动,边界问题一直以来是困扰学生的难点,因为它深刻地考量学生的思维品质,破解此类题型,需要把三个圆有机结合起来,这三个圆就是共点圆、圆心圆和弦长圆.1三种圆的概念1.1共点圆过平面内某一定点、半径相等的圆有无穷多个,这一系 Because the charged particles move in the bounded uniform magnetic field, the boundary problem has always been a difficult problem for students. Because it deeply considers the thinking quality of students and resolves such questions, it is necessary to combine the three circles organically. Is a total of round, round and chord long round.1 The concept of three kinds of circles 1.1 total point over a certain point in the plane, the circle of equal radius there are infinitely many, this system