Also known an ‘inductive charging’, wireless charging uses magnetism to charge a battery without a cabled connection between the charger and the device. It works by creating a magnetic field in a coil located in the charger, which them induces a similar field in a coil in the device and is converted into power. A newer technique called ‘resonance charging’ also uses a pair of coils, but can operate over a distance of a few centimetres rather than requiring physical contact.