In this experiment we will use a compass to study the rate at which a temporary magnet relaxes .

在本实验中，我们将用指南针来研究 暂时 磁铁的驰豫率。

A temporary magnet made by coiling wire around an iron core ; when current flows in the coil the iron becomes a magnet .

由在铁芯上缠绕的线圈构成的 临时 磁铁；当电流通过线圈铁芯就会变成磁体。