Researchers at the TED conference in Oxford showed how mobile phones and televisions could be charged wirelessly.

Say goodbye to plugs and cables – the era of wire-free power has moved a step closer, after scientists showed how mobile phones and televisions could be powered using simple physics.

Eric Giler, chief executive of Witricity, a US firm building wireless electricity systems, said that the technology could eventually replace batteries as well as conventional power sources.

"There is something like 40 billion disposable batteries built every year for power that, generally speaking, is used within a few inches or feet of where there is very inexpensive power," he told delegates at the TED technology, entertainment and design conference in Oxford.

Giler showed how a T-Mobile G1 phone, running Google’s Android operating system, could be charged using wireless electricity, as could an Apple iPhone. He said that the technology could appeal especially to television manufacturers. With an increasing number of flat-screen TVs wall-mounted rather than placed on stands, he said that witricity could help do away with unsightly trailing cables.

Wireless electricity is achieved through "electromagnetic resonance", a physical phenomenon whereby objects with the same resonant frequency can transfer energy between them without having an impact on other nearby objects. It’s the same principle which can cause glass to shatter when exactly the right musical note is hit at the correct pitch.

The witricity system uses two "coils" that share the same frequency to transfer this energy, with one coil connected to the power source and the other embedded within the gadget. Energy flows between the two coils, and a voltage will begin to build up in the coil embedded inside the gadget, powering the device.

In time, says Giler, the power coils could be embedded in the ceiling or floor, or near a desk, and could automatically start to charge a wide variety of gadgets as soon as they are in range.