The forceline and potential gradient equation are deduced.
同时推导出其电力线方程和电位线方程。
2
The rotation will last for ever if the permanent magnetic ring and the magnetic forceline of the permanent magnet SN exist for ever.
只要永磁环和永磁体sn的磁力线永久存在，旋转也将始终存在。
3
The paper expounds the principle and the method of measuring zenith distance for celestial positioning based on the direction of gravitational forceline.