magnetic density

例句：

1. 1.The magnetized iron bar is attracting the steel ball.
   被磁化的铁棒正在吸引钢球。
2. 2. The magnetic field of the Earth affects the movement of objects on the surface.
   地球的磁场影响地表物体的运动。
3. 3.The researcher found that the magnetic density of the sample was higher than expected.
   研究人员发现样本的磁密度高于预期。