為什麼會這樣
解釋
An RC circuit turns capacitor storage into a time-response story. The resistor limits how fast charge can move, the capacitor stores that charge as voltage builds across its plates, and the time constant tau = RC tells you whether the response is fast or slow.
This bench stays intentionally small: one battery, one resistor, one capacitor, and one charge-versus-discharge toggle. That is enough to show why capacitor voltage does not jump instantly, why current is largest right at the start, and how stored energy follows the same changing voltage without turning the page into a general transient-circuit simulator.