Wireless power system

The system uses two coils, one at the mains and one on the gadget, both of which have been engineered with the same resonant frequency. When connected up to an electricity supply, the mains coil produces a magnetic field that resonates with the second coil, allowing voltage to build up to power the gadget.

Source: http://news.bbc.co.uk/2/hi/technology/8165928.stm