学生甲:老师,上次您跟我们讲了如何区分“电源”、“负载”的问题,使我们弄懂了不少问题,收获很大。学生乙:老师,我还想提出一个问题,请您给我们解释一下。就是关于电容器的问题,它在电路中到底算是电源还是负载呢?老师:你的问题提得很好,这说明你肯动脑筋思考问题,这个问题在上次我们的确没有讨论到。电容器的基本作用是什么呢?学生甲:是充电和放电。老师:对了,那么在电容器充电和放电时,电路中的电荷是怎样定向移动的呢? Student A: Teacher, the last time you told us how to distinguish between “power supply” and “load”, which made us understand a lot of problems and achieved great results. Student B: Teacher, I would also like to ask a question. Please explain it to us. It is about the capacitor. Is it a power supply or a load in the circuit? Teacher: Your question is very good. This shows that you are willing to use your brain to think about the problem. This problem was not discussed in the last time. What is the basic role of a capacitor? Student A: It is charged and discharged. Teacher: Yes, how does the charge in the circuit move when the capacitor is charged and discharged?