A capacitor is like a rubber membrane that has elasticity. When the capacitor/rubber membrane is stretched to its limit, it either breaks (dielectric breakdown) or it releases that energy causing a flow in the opposite direction.
A sand filter has no limit (as it gets more clogged, it starts resembling a closed valve) and it can't release built up energy (flowing in the opposite direction just "opens the valve")
A sand filter has no limit (as it gets more clogged, it starts resembling a closed valve) and it can't release built up energy (flowing in the opposite direction just "opens the valve")