A power adapter between an alternating current (AC) source and an external direct current (DC) consumer device consumes no electrical power until the DC device is connected to the power adapter. The power adapter includes a first magnet, a second magnet which is repelled by the first magnet, and a movable conductive member arranged on the second magnet. The insertion of the external DC device pushes the second magnet towards the first magnet and establishes a connection between the AC power source and the power adaptor. When the external device is removed, the movable conductive member is driven away by a repulsive force between the magnets to disconnect the external AC power source from the power adapter.