在做中学物理实验时,为增加其直观性和可对比性,往往要求研究对象同时开始运动,但这一要求不易实现.但若利用电磁铁来辅助,就容易实现了.电磁铁原理是电流的磁效应,线圈两端相当于条形磁铁两极,线圈的极性可用安培定则来判别.电磁铁的最大优点是其磁性的有无及强弱容易控制.利用 In doing physics experiments in middle school, in order to increase its visual and comparative, often require the study object to start at the same time, but this requirement is not easy to achieve, but if the use of electromagnets to assist, it is easy to achieve.Magnet principle is current Of the magnetic effect, the two ends of the coil is equivalent to two bars of magnets, the polarity of the coil can be used to determine the polarity of Ampere. The biggest advantage of the magnet is its magnetic strength and weak easy to control.