一天,一个学生向我提出这样一个问题,筒状磁铁的磁场方向是否与通电螺线管磁场方向完全相同?我思考片刻后,做了肯定回答,完全相同。我当时是这样考虑的,通电螺线管磁场方向与条形磁铁、柱形磁铁磁场方向完全相同:在外部,磁感线是由北极出来,回到南极;在内部,磁感线方向是由南极指向北极,并和外部磁感线相连,形成闭合曲线。如 One day, a student asked me this question: Is the direction of the magnetic field of the cylindrical magnet exactly the same as the direction of the magnetic field of the energized solenoid? After I think about it for a moment, I make an affirmative answer, exactly the same. I was thinking about it this way. The field direction of the energized solenoid is exactly the same as that of the magnets of the bar magnets and the columnar magnets. On the outside, the lines of magnetic induction come from the north pole and return to the south pole; internally, the direction of the lines of magnetic induction is caused by The South Pole points to the North Pole and is connected to external magnetic lines of inductance to form a closed curve. Such as