磁铁在无限大薄导体板上方低速运动的磁阻尼探究

Research on magnetic damping of magnet moving at low speed above infinite thin conductor plate

本文基于麦克斯韦涡流镜像理论,定量计算了在无限大薄导体板上方低速运动的磁铁所受阻力的表达式,其正比于运动速度、磁矩的平方和导体板厚度,并以磁铁离导体板距离的4次方关系减小.用改进单摆法构建了磁单摆-铝箔系统进行实验,控制其他变量不变,改变磁铁离铝箔的最小距离并进行多次实验,发现理论与实验符合较好.

Based on Maxwell s eddy current mirror image theory,the resistance expression of magnet moving at low speed above an infinite thin conductor plate is quantitatively calculated.It is found that the resistance is proportional to the moving speed,the square of magnetic moment,the thickness of conductor plate,and decreases with the fourth power of the distance between magnet and conductor plate.The magnetic pendulum-aluminum foil system is constructed by improving pendulum experiment with other variables keeping unchanged.The minimum distance between the magnet and the aluminum foil is changed for several times.The results obtained from the theory and the experiment are in good agreement.