Wireless power transmission

Apparatus and methods for extracting wirelessly transmitted electrical power are described. A wireless electrical power receiver comprises a receiver resonator arranged to inductively generate an AC electrical current and a rectifier to receive and convert the AC electrical current from the receiver resonator into DC electrical power which is supplied to a load. A switching arrangement can selectively provide a short circuit to retain the AC electrical current within the receiver resonator when the switch is operated and a controller can supply a control signal to operate the switching arrangement to control the AC electrical current supplied to the rectifier.