So there is an electrical circuit into the card and when you open it, it moves a membrane and the membrane makes the music.

所以卡中有一个电路，当你打开它时，它会移动薄膜，薄膜就会出音乐。

It functions in the circuit as a capacitor, and when radio waves pass through the antenna, the minuscule voltage shifts make the membrane bounce like a trampoline.

这种部件在电路中起电容用，当无线电波通过天线时，微小位移电压让薄膜像蹦床一样弹起来。