A power-transmitter-unit comprising: a power-transmitting-coil for wirelessly providing power to a power-receiver-unit, and a resonant-capacitor connected in series to the power-transmitting-coil, such that together they define an LC circuit, wherein the LC circuit comprises a first-end and a second-end; a power-stage for selectively providing power to the LC circuit; a controller configured to define a power-transmission-mode of operation and a foreign-object-detection-mode of operation and to switch from the power-transmission-mode of operation to the foreign-object-detection-mode of operation, wherein: in the power-transmission-mode of operation: the power-stage is configured to provide a potential-difference across the first-end and the second-end of the LC circuit; in the foreign-object-detection-mode of operation: for a recuperation-time-interval, the power-stage is configured to provide a potential-difference across the first-end and the second-end of the LC circuit that has the opposite polarity to the current through the power-transmitting-coil; after expiry of the recuperation-time-interval, the first-end of the LC circuit is connected to the second-end of the LC circuit such that the LC circuit is short-circuited and defines a closed-LC-circuit; and the controller is configured to receive measured-signalling that is representative of an operating parameter of the power-transmitter-unit; wherein the controller is further configured to: process the measured-signalling in order to provide an indication of whether or not a foreign object has been detected. a power-transmitting-coil for wirelessly providing power to a power-receiver-unit, and a resonant-capacitor connected in series to the power-transmitting-coil, such that together they define an LC circuit, wherein the LC circuit comprises a first-end and a second-end; a power-stage for selectively providing power to the LC circuit; a controller configured to define a power-transmission-mode of operation and a foreign-object-detection-mode of operation and to switch from the power-transmission-mode of operation to the foreign-object-detection-mode of operation, wherein: in the power-transmission-mode of operation: the power-stage is configured to provide a potential-difference across the first-end and the second-end of the LC circuit; in the foreign-object-detection-mode of operation: for a recuperation-time-interval, the power-stage is configured to provide a potential-difference across the first-end and the second-end of the LC circuit that has the opposite polarity to the current through the power-transmitting-coil; after expiry of the recuperation-time-interval, the first-end of the LC circuit is connected to the second-end of the LC circuit such that the LC circuit is short-circuited and defines a closed-LC-circuit; and the controller is configured to receive measured-signalling that is representative of an operating parameter of the power-transmitter-unit; in the power-transmission-mode of operation: the power-stage is configured to provide a potential-difference across the first-end and the second-end of the LC circuit; in the foreign-object-detection-mode of operation: for a recuperation-time-interval, the power-stage is configured to provide a potential-difference across the first-end and the second-end of the LC circuit that has the opposite polarity to the current through the power-transmitting-coil; after expiry of the recuperation-time-interval, the first-end of the LC circuit is connected to the second-end of the LC circuit such that the LC circuit is short-circuited and defines a closed-LC-circuit; and the controller is configured to receive measured-signalling that is representative of an operating parameter of the power-transmitter-unit; for a recuperation-time-interval, the power-stage is configured to provide a potential-difference across the first-end and the second-end of the LC circuit that has the opposite polarity to the current through the power-transmitting-coil; after expiry of the recuperation-time-interval, the first-end of the LC circuit is connected to the second-end of the LC circuit such that the LC circuit is short-circuited and defines a closed-LC-circuit; and the controller is configured to receive measured-signalling that is representative of an operating parameter of the power-transmitter-unit; wherein the controller is further configured to: process the measured-signalling in order to provide an indication of whether or not a foreign object has been detected.