Wireless technology used to power light bulb

[Wayne Harrison]

CAMBRIDGE, MASS. — Researchers at the Massachusetts Institute of Technology made a 60-watt light bulb glow by sending it energy wirelessly — from a device 7 feet away — potentially heralding a future in which cellphones and other gadgets get their juice without having to be plugged in.

The breakthrough, disclosed Thursday in Science Express, the online publication of the journal Science, is being called "WiTricity" by the scientists.

The concept of sending power wirelessly isn't new, but it has been dismissed as inefficient because the electromagnetic energy generated by the charging device radiates in all directions.

One advance was announced last fall, when MIT physics professor Marin Soljacic said he had figured out how to use specially tuned waves that don't radiate as much. The key is to get the recharging device and the gadget that needs power on the same frequency, similar to how a radio picks up only one station at a time.

Soljacic's team also stresses that this "magnetic coupling" has a low range and is safe for humans and other living things.

The next step was to demonstrate the principle in experiments, which is what was described in the new paper in Science.

The MIT team said it found success with the 60-watt light bulb that had "no physical connection" with the power-generating appliance.

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