AC behavior of a capacitor
The current does not actually "pass through." Charge flowing into one terminal of a capacitor accumulates and forces charge to flow out the other terminal of a capacitor causing that side to have a deficit of charge. In effect, that is current, but the current stops when the capacitor is charged to a voltage that equals the source voltage. When the source voltage reverses, the accumulated charge reverses direction of flow. With AC current, the process in continuous.