Wireless charging of electric cars looks increasingly promising

THEY MAY BE facing extinction in the electric-transport revolution, but one benefit of cars with internal combustion engines is that they are easy and quick to refuel, so travelling a long way in one is rarely a problem. Not so for their successors. In the absence of universal standards, electric cars come with a variety of charging systems and different sorts of cables and sockets. Extended journeys therefore need careful planning to make sure that the battery is fully charged at the start and that compatible fast-charging stations are available en route.It would be much more convenient if electric cars could be recharged wirelessly. Some electric toothbrushes and other small devices, such as mobile phones, can already be topped up in this way using a process called electromagnetic induction. This employs an alternating mains current flowing through a coil to create a varying magnetic field, which then generates another current in a second coil placed alongside it according to principles elucidated in the 19th century by Michael Faraday. The device containing the second coil then converts the transmitted power into direct current, which is used to recharge a battery.