11. Ball on Ferrite Rod 铁氧体棒上的球

A ferrite rod is placed at the bottom end of a vertical tube. Apply an ac voltage, of a frequency of the same order as the natural frequency of the rod, to a fine wire coil wrapped around its lower end. When a ball is placed on top of the rod, it will start to bounce. Explain and investigate this phenomenon.

一个铁氧体棒被放置于一个竖直(垂直)管道.施加一个与棒本征频率相同数量级频率的交变电压至包裹于其底部的一个好的线圈.当一个球被放置于棒上时,其将发生弹跳.解释并研究这一现象.

需要注意的问题:好的线圈是什么,棒本征频率又是什么