图 1是电磁振荡与电磁振荡的周期和频率这两节课实验的原理图。两个实验为 :(1) K先跟 E闭合 ,给电容 C充电 ,然后将 K扳向线圈 L,就会看到电流表 G的指针左右摆动 ,这说明电路里有振荡电流。(2 )改变 L或 C量的大小 ,电流表 G指针摆动的快慢也随之改变 ,进一步研究得知 :T =2 Fig. 1 is a schematic diagram of the experiments of the two periods of electromagnetic oscillation and electromagnetic oscillation cycle and frequency. Two experiments are: (1) K closes with E, charges capacitor C, and then pulls K toward coil L, and then the pointer of current meter G swings. This shows that the circuit has oscillating current. (2) To change the magnitude of L or C, the speed of the G pointer swings in the ammeter also changes. Further study shows that: T = 2