The future of phone charging will rid your home of untidy wires. Most wireless chargers use electromagnetic induction. The charging pad contains a wire coil, through which an alternating electric current is passed to create a pulsing magnetic field. At the other end, your mobile phone has its own coil, which reacts to the magnetic pulses by producing a corresponding alternating electric current. This is converted into direct current to power the device. Wireless charging is less efficient than cable charging and the magnetic field strength falls off very quickly with range. But recently, a company called uBeam has demonstrated longer range wireless charging that works by beaming ultrasound waves that are converted into electricity in your phone by piezoelectric transducers.