English: Block diagram of a wireless power transmission system that uses capacitive plates to transfer power. This is a so-called "monopolar" circuit that uses only one pair of plates. The two plates P1 and P2 function as a capacitor, with the space between as the dielectric. An alternating voltage on the driver plate P1 induces an alternating potential on the receiver plate P2 by electrostatic induction. Both the transmitter and the receiver use "passive" plates P3 and P4, large in area compared to P1 and P2, as "charge sinks", or grounds, to eliminate the need for a "return path" for the alternating current. This system is being applied to charging of mobile devices such as laptops. A laptop with a capacitive plate P2 embedded in its bottom surface would be placed on a charging pad with a driving plate P1 embedded in its surface, transferring power which would be rectified to charge its batteries. The advantage of this system is each device has only one plate, while "bipolar" capacitive systems have two plates each, which must be aligned with two corresponding plates in the charging surface for the charger to work.